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  Acoustic Monitoring Program: T-Phase Bibliography  

Technically, a T-phase is a seismic phase recorded on land-based instruments in which part of the propagation path from source to receiver is through the oceans. The source of the seismic energy includes earthquakes, underground or underwater explosions, and submarine volcanism (with apologies to J. Northrop; see Northrop 1968). In compiling this reference list, we have used a looser definition of the T-phase. References to acoustic phases that are recorded on hydrophones from underground sources in which body wave energy is converted to underwater acoustic energy are also included in this list. We have also included references to submarine volcanic activity detected by hydrophones. Finally, in order to gain a better historic perspective, pioneering theoretical work which had a major role in understanding the excitation and propagation of T-phases are also listed.

References and editorial comments to references provided by C.E. Nishimura, Acoustics Division, Naval Research Laboratory, Washington, D.C. 20375. References and descriptions since 1991 provided by R.P. Dziak, Oregon State University, NOAA-PMEL/T-phase Project, Newport, OR, 97365. If the reader of this document is aware of references that should be included in this list but are not, please send email reference information to


Chaytor, J., C. Goldfinger, R.P. Dziak, C.G. Fox, Active deformation of the Gorda "Plate": Constraining deformation models with new geophysical data, Geology, in press 2004.

Davis, E., K. Becker, R. Dziak, J. Cassidy, K. Wang, and M. Lilley, A Seafloor Spreading Episode on the Juan de Fuca Ridge: Evidence for a Co-seismic crustal dilatation and hydrothermal "anti-plume", Nature, in review, 2004

Dziak, R.P., D. R. Bohnenstiehl, H. Matsumoto, C. G. Fox, D. K. Smith, M. Tolstoy, T-K Lau, J. H. Haxel, M. J. Fowler, P- and T-wave detection thresholds, Pn velocity estimate, and detection of lower mantle and core P-waves on ocean sound-channel hydrophones at the mid-Atlantic Ridge, Bull. Seism. Soc. Am., in press 2004.

Dziak, R.P., D. Smith, D. Bohnenstiehl, C. Fox, D. Desbruyeres, H. Matsumoto, M. Tolstoy, and D. Fornari, Evidence of a recent magma dike intrusion at the slow-spreading Lucky Strike segment, Mid-Atlantic Ridge, J. Geophys. Res., in review, 2004.

Dziak, R., J. Goslin, D. Smith, N. Lourenço, D. Bohnenstiehl, H. Matsumoto, C. Fox, M. Tolstoy, J. Luis, Long-term Monitoring of Northern Mid-Atlantic Ridge Earthquake Activity Using Autonomous Hydrophone Arrays, Proceedngs from the RIDGE 2000 Workshop on the Mid-Atlanitc Ridge, March 1-3, 2004.

Graeber, F. M., Piserchia, P.-F. (2004) T-phase excitation in the NE Indian Ocean mapped using variations in backazimuth over time obtained from Multi-Channel Correlation of IMS hydrophone triplet data, Geophysical J. International, 158, 239-256.

Smith, D.K., R.P. Dziak, H. Matsumoto, C.G. Fox, and M. Tolstoy, Autonomous Hydrophone Array Monitors Seismic Activity at Northern Mid-Atlantic Ridge, Eos Transactions, AGU, 85, No 1., 1-5, 2004.

Bohnenstiehl, D.R. M. Tolstoy, D.K. Smith, C.G. Fox and R.P. Dziak, Time clustering behavior of earthquakes along the Mid-Atlantic Ridge 15°-35°N: Observations from hydroacoustic monitoring, Phys. Earth and Planet. Int., 138, No 2, 147-161, 2003.

Bohnenstiehl, D.R. and M. Tolstoy, Comparison of teleseismic- and hydroacoustic-derived earthquake locations along the north-central Mid-Atlantic Ridge and equatorial East-Pacific Rise, Seismol. Res. Lett., 74, 791-802, 2003.

Cowen, J., E. T. Baker, R.P. Dziak, and M. Lilley, Time-Critical Studies: Rapid response to Transient Dynamic Mid-Ocean Ridge Events (abstract), Eos Transactions, American Geophysical Union, Fall Meeting, 2003.

Dziak, R.P., W. W. Chadwick, Jr., C. G. Fox, and R. W. Embley, Hydrothermal temperature changes at the southern Juan de Fuca Ridge associated with a Mw 6.2 Blanco Transform earthquake. Geology, v. 31, no. 2, p. 119-122, 2003.

Dziak, R., M. Park, H. Matsumoto, C. Fox, S.-K. Byun, M. Fowler, J. Haxel, and R. Embley, Hydroacoustic Records of the First Historical Eruption of Anatahan Volcano, Mariana Islands (abstract), Eos Transactions AGU, Fall Meeting, 2004.

Goslin, J, N. lourenco, R.P. Dziak, D. Bohnenstiehl, J. Haxel, Long-term Seismicity of the Reykjanes Ridge (North Atlantic) Recorded by a Regional Hydrophone Array (abstract), European Union of Geosciences, Sprint Meeting, Nice, France, 2004.

Okal, E.A., P-J. Alasset, O. Hyvernaud, and F. Schindele, The Deficient T waves of Tsunami Earthquakes, Geopys. J. Int., 152, 416-432, 2003.

Okal, E.A., T waves from the 1998 Papua New Guinea Earthquake and Its Aftershocks: Timing the Tsunamigenic Slump, Pure and Appl. Geophys., 160, 1843-1863, 2003.

Park, M. , R. Dziak , S.-K. Byun , and C. Fox, and H. Matsumoto, Numerical Modeling of Sound from the Eruption of Anatahan Volcano, Mariana Islands (abstract), Eos Transactions AGU, Fall Meeting, 2004.

Reymond, D., O. Hyvernaud, J. Talandier, E.A. Okal, T-wave Detection of Two Underwater Explosions off Hawaii on 13 April 2000, Bull. Seism. Soc. Am., 93, No. 2, 804-816, 2003.

Smith, D.K., J. Escartin, M. Cannat, M. Tolstoy, C.G. Fox, D. R. Bohnenstiehl, S. Bazin, Spatial and temporal distribution of seismicity along the northern Mid-Atlantic Ridge (15-35°N), J. Geophys. Res., 108, 2167, 10.1029/2002JB001964, 2003.

Talandier, J., and E.A. Okal, Hydroacoustic signals from presumed CHASE explosions off Vancouver Island in 1969-70: A modern perspective, Seismol. Res. Letts., in press, 2003.

Yang, Y and D.W. Forsyth, Improving epicentral and magnitude estimation of earthquakes from T-phases by considering the excitation function, Bull Seism.Soc. Am., 93, 5, 2106-2122, 2003.

Bohnenstiehl, D.R., M. Tolstoy, R.P. Dziak, C.G. Fox, and D.K. Smith, Aftershocks in the mid-ocean ridge environment: An analysis using hydroacoustic data, Tectonophysics 354, 49-70, 2002.

Butler, R. and C. Lomnitz, Coupled Seismoacoustic Modes on the Seafloor, Geophys. Res. Lett, 29, No 10, 10.1029/2002GL014722, 2002

Dziak, R.P. and C.G. Fox, Evidence for Harmonic tremor detected Across the Pacific Ocean Basin, J. Geophys.Res., vol. 29, no. 12, 10.1029/2001GL01391, 2002.

Pulli, J. J., and Z. M. Upton, Hydroacoustic Observations of Indian Earthquake Provide New Data on T-waves, Eos Transactions, Am. Geophys. Un., 83, No. 13, 2002.

Smith, D. K., M. Tolstoy, C. G. Fox, D. R. Bohnenstiehl, H. Matsumoto, and M. J. Fowler, Hydroacoustic monitoring of seismicity at the slow-spreading Mid-Atlantic Ridge. Geophys,Res. Lett., 29, no.12, 10.1029/2001GL01391, 2002.

Talandier, J., O. Hyvernaud, E.A. Okal, and P.-F. Piserchia, Long-range detection of hydroacoustic signals from large icebergs in the Ross Sea, Antarctica, Earth Planet. Sci. Letts., 203, 519-534, 2002.

Caplan -Auerbach, J., C.G. Fox, F.K. Duennebier, Hydroacoustic Detection of Submarine Landslides on Kilauea Volcano, Geophys. Res., Lett., 28, No. 9, 1811-1813, 2001.

Dziak, R.P., Empirical Relationship of T-wave Energy and Fault Parameters of Northeast Pacific Ocean Earthquakes, Geophys. Res. Lett., 28, 2537-2540, 2001.

Fox, C.G., H. Matsumoto, and T.K.A. Lau, Monitoring Pacific Ocean seismicity from an autonomous hydrophone array, J. Geophys. Res., 106, 4183-4206, 2001.

Johnson, H.P., R.P. Dziak, C.R. Fisher, C.G. Fox, and M.J. Pruis, Earthquakes Influence Distant Hydrothermal Vents: The Far-field Effect and Delayed Response, Eos Transactions AGU, 82, 233-236, 2001

Okal, E.A, T-phase Stations for the International Monitoring System of the Comprehensive Nuclear-Test Ban Treay: A Global Perspective, Seism. Res. Lett., 72, No. 2, 186-196, 2001.

Sohn, R.A. and J.A Hildebrand, Hydroacoustic earthquake detection in the Arctic Basin with the Spinnaker Array, Bull Seism. Soc. Am., 572-579, 2001.

Dziak, R.P., C.G. Fox, R.W. Embley, J.L. Nabelek, J. Braunmiller, and R.A. Koski. Recent Tectonics of the Blanco Ridge, Eastern Blanco Transform Fault Zone, Mar. Geophys. Res., 21 (5), 423-450,2000.

Johnson, H.P., M.A. Hutnak, R.P. Dziak, C.G. Fox, I. Urcuyo, C. Fisher, J.P. Cowen, J. Nabelek, Earthquake-Induced Changes in a Hydrothermal System at the Endeavour Segment, Juan de Fuca Ridge, Nature, 407, 174-177, 2000.

Orcutt, J., E. Bernard, C.-S. Chiu, C. Collins, C. deGroot-Hedlin, R. Dziak, C. Fox, W. Hodgkiss, W.Kuperman, J. Mercer, W. Munk, R. Odom, M. Park, D. Soukup, R. Spindel, F. Vernon, and P. Worcester, Long-term observations in acoustics the Ocean Acoustic Observatory Federation. Oceanography, 13(2), 57-63, 2000.


Dziak, RP and C.G. Fox, Long-term seismicity and ground deformation at Axial Volcano, Juan de Fuca Ridge, Geophys Res. Lett., v:26, 3641-3644, 1999.

Dziak, RP and C.G. Fox, The January 1998 earthquake swarm at Axial Volcano, Juan de Fuca Ridge: Hydroacoustic evidence of a seafloor volcanic activity, Geophys Res. Lett., v:26, 3429-3432, 1999.

Dziak, RP, C.G. Fox, S.R. Hammond, T-K Lau, H. Matsumoto, A.E. Schreiner, Real-Time detection of earthquake swarms using the SOSUS hydrophone array: Hydroacoustic evidence of dike injections and seafloor eruptions, Proceedings: Juan de Fuca Ridge Results Symposium: A Retrospective., Seattle, WA, November 7-9, 1999.

Dziak, RP and C.G. Fox, New insights into the seismotectonics of NE Pacific ocean spreading centers, transform faults, and microplates from hydroacoustic monitoring, IUGG/IASPEI., Symposium on Seismotectonics, Birmingham, UK, July, 1999.

Fox, C.G. and RP Dziak, Internal deformation of the Gorda Plate using hydroacoustic monitoring methods. J. Geophys. Res., v:104, 17603-17615, 1999.

Fox,C.G. and RP Dziak, Long-term monitoring of oceanic seismicity using underwater acoustic techniques, IUGG/IASPEI., Symposium on Seismotectonics, Birmingham, UK, July, 1999.

Slack, P.D., C.G. Fox, and RP Dziak. P wave detection thresholds, Pn velocity estimates, and T-wave location uncertainty from oceanic hydrophones. J. Geophys. Res., 104: 13061-13072, 1999.


de Groot–Hedlin, C.D., and J. Orcutt. Synthesis of earthquake generated T-waves, Geophys. Res.; ett., n v:26, 1227-1230, 1998.

Dziak, RP and C.G. Fox, Hydroacoustic Detection of Submarine Volcanic Activity at Axial Volcano, Juan de Fuca Ridge, January 1998, Eos Transactions, American Geophysical Union, San Francisco, CA, v:79, No. 46, November 12, 1998.

Fowler, M.J., RP Dziak, and C.G. Fox, Improved Hydroacoustic Locations of Northeast Pacific Ocean Earthquakes derived from Military Hydrophone Arrays, Eos Transactions, American Geophysical Union, San Francisco, CA, v:79, No. 46, November 12, 1998.

Fox, C.G. and R.P. Dziak Hydroacoustic Detection of Volcanic Activity on the Gorda Ridge, February - March 1996, Deep Sea Res. II, 45: 2513-2530, 1998.

Description of seismicity associated with a seafloor eruption and dike injection along the northern Gorda Ridge. A total of 4093 earthquakes were detected over a 3 week period on the U.S. Navy’s SOSUS hydrophones. The earthquakes migrated a distance of 35 km over a 24 hr period (speed of ~ 0.55 m/s), likely following the propagation of dike through the shallow oceanic crust.

Fox, C.G. and RP Dziak, Hydroacoustic Monitoring of Deep Ocean Earthquakes Using the SOSUS Hydrophone Arrays, , Eos Transactions, American Geophysical Union, San Francisco, CA, v:79, No. 46, November 12, 1998

Hanson, J.A., and H.K Given. Accurate azimuth estimates from a large aperture hydrophone array using T-phase waveforms. Geophys. Res. Lett., 25:365-368, 1998

Okal, E.A., and J. Talandier. Correction to T waves from the Great 1994 Bolivian Deep Earthquake in Relation to Channeling of S wave Energy up the Slab. J. Geophys. Res., 103, 2793-2794, 1998.

Talandier, J., and E.A. Okal. On the mechanism of conversion of seismic waves to and from T-waves in the vicinity of island shores. Bull Seism. Soc. Am., 88, 621, 1998.

This paper considers the conversion of seismic waves to and from T-waves in the vicinity of islands. They found that the steep island slopes play a pivotal role in allowing efficient conversion between P-waves in the island structure and T-waves in the water column.


Blackman, D.K., And JA Orcutt. Seismoacoustic Recordings of a Volcanic Event on the Mohns Ridge. J. Acoust. Soc. Am.(abstract), 105, 3069, 1997.

Dziak, RP, C.G. Fox, H. Matsumoto, and AE Schreiner. The 1992 Cape Mendocino Earthquake Sequence: Seismo-Acoustic Analysis Using Fixed Hydrophone Arrays. Mar. Geophys. Res., v:19, 137-162, 1997.

Dziak, RP and C.G. Fox. Long-Term Seismicity and Ground Deformation at Axial Volcano, Juan de Fuca Ridge. Eos Transactions, American Geophysical Union, San Francisco, CA, v:78, No. 46, November, 1997.

Fox, C.G. and RP Dziak. Hydroacoustic Monitoring of Magmatic Activity on the Mid-Ocean Ridge. Eos Transactions, American Geophysical Union, San Francisco, CA, v:78, No. 46, November, 1997.

Fox, C.G. Hydroacoustic Monitoring of the Distribution of Magmatic Activity on the Mid-Ocean Ridge. European Geophysical Society, Vienna, Austria, April, 1997.

Hanson, JA, and H.K. Given. Performance of an Island Seismic Station for Observing Hydroacoustic T-phases. Eos Transactions (abstract), American Geophysical Union, San Francisco, CA, v:78, No. 46, November, 1997.

Hanson, JA, and H.K. Given. Locating ridge seismicity near Ascension Island using hydroacoustic and seismic data, J. Acoustic Soc. Am.(abstract), 105, 3070, 1997.

McLaughlin. T-phase Observations at San Nicolas Island, California. Seism. Res. Lett. (abstract), v:68, 296, 1997.

Okal, E.A., And J. Talandier. T waves from the Great 1994 Bolivian Deep Earthquake in Relation to Channeling of S wave Energy up the Slab, J. Geophys Res., 102, 27421-27437, 1997.

Pasyanos, M. E., and B. Romanowicz. Observations of T-phases Across Northern California Using the Berkeley Digital Seismic Network. Eos Transactions (abstract), American Geophysical Union, San Francisco, CA, v:78, No. 46, November, 1997.

Piserchia, P-F, J. Virieux, D. Rodrigues, S. Gaffet, and J. Talandier. A Hybrid Numerical Model of T-wave propagation: Application to the Mid-plate Experiment. Geophys. J. Int., 1997


Chapman, N.R. and R. Marrett. Acoustic T-phase Directionality Measurements Using a Towed Line Array. J. Acoust. Soc Am. (abstract), v:100, No.4, 2641, 1996.

Duennebier, F.K., And C.N. McCreery The Earthquake T phase: MILS Hydrophone Array Results. J. Acoust. Soc Am. (abstract), v:100, No.4, 2638, 1996.

deGroot-Hedlin, C., and J. Orcutt. Observations of Hydro-acoustic Phases from Submarine Earthquakes in the Pacific. Eos Transactions (abstract), American Geophysical Union, San Francisco, CA, v:61, No.43, November, 1996.

Dysart, P.S., H.W. Laney, and R. Willemann. Hydroacoustic Event Detection and Classification at Point Sur and Wake Island. Eos Transactions (abstract), American Geophysical Union, San Francisco, CA, v:61, No.43, November, 1996.

Dziak, RP, C.G. Fox, R.W. Embley, J.E. Lupton, G.C. Johnson, W.W. Chadwick, and R.A. Koski. Detection of and Response to a Probable Volcanogenic T-wave Event Swarm on the Western Blanco Transform Fault Zone. Geophys Res. Lett., v:23, No. 8, 873-876, 1996.

Dziak, RP, C.G. Fox, and P.D.Slack. T-wave Source Level and Earthquake Fault Parameters: Empirically Derived Scaling Relationships. J. Acoust. Soc Am. (abstract), v:100, No.4, 2639, 1996.

Dziak, RP and C.G. Fox. Seismoacoustic Analysis of Tectonic Activity Along Northeast Pacific Ocean Transform Faults. European Seismological Commission, XXV General Assembly (abstract), Reykjavik, Iceland, September, 1996.

Fox, C.G. and RP Dziak. Monitoring Volcanism on the Mid-Ocean Ridge Using Hydroacoustic Techniques. European Seismological Commission, XXV General Assembly (abstract), Reykjavik, Iceland, September, 1996.

Fox, C.G., and RP Dziak. Monitoring Microseismicity in the Northeast Pacific Using Hydroacoustic Techniques. J. Acoust. Soc Am. (abstract), v:100, No.4, 2638, 1996.

Hanson, JA, H.K. Given, and J. Berger. Earthquake activity near Ascension Island, south Atlantic Ocean, as seen by a combined seismic/hydrophone array, Geothermics, 25: 507-519, 1996.

Harris, B.H., And T.F. Hauk. Acoustic Array Observation of Seismic Events. J. Acoust. Soc Am. (abstract), v:100, No.4, 2640, 1996.

Hildebrand, JA, C.G. Fox, and RP Dziak. A Multipath Model for T-wave Generation of Seafloor Earthquakes. J. Acoust. Soc Am. (abstract), v:100, No.4, 2639, 1996.

Keenan, R.E. Arctic Abyssal T-phase Coupling to the Ocean Acoustic Channel. J. Acoust. Soc Am. (abstract), v:100, No.4, 2640, 1996.

Laney, H.W., P. Dysart, H. Freese, and R.J. Willemann. An Automated System for Detecting and Classifying In-Water Explosions and T-phases. J .Acoust. Soc Am. (abstract), v:100, No.4, 2641, 1996.

Lysanov, Y.P. Trapping of Hydroacoustic Waves Generated by Underwater Earthquakes Into a Sound Channel. J. Acoust. Soc Am. (abstract), v:100, No.4, 2641, 1996.

Okal, E.A., And J. Talandier. T-wave Detection of Underwater Volcanism by Land-based Seismic Stations: The Example of the Hollister Ridge. J. Acoust. Soc Am. (abstract), v:100, No.4, 2640, 1996.

Schmidt, H. and J.T. Goh. Modeling Oceanic T-phase Generation Using Coupled Wave-Number-Integration Approaches. J. Acoust. Soc Am. (abstract), v:100, No.4, 2641, 1996.

Sperry, B., J.T. Goh, and H. Schmidt. Possible Mechanisms for T-phase Generation. J. Acoust. Soc Am. (abstract), v:100, No.4, 2641, 1996.

Talandier, J., and E.A. Okal. T waves from underwater volcanoes in the Pacific Ocean: Ringing witnesses to geyser processes?, Bull. Seism. Soc. Am., 86, 1529-1544, 1996


Fox, C.G., W.E. Radford, RP Dziak, T-K Lau, H. Matsumoto, and AE Schreiner. Acoustic Detection of a Seafloor Spreading Episode on the Juan de Fuca Ridge Using Military Hydrophone Arrays. Geophys Res. Lett., v:22, No. 2, 131-134, 1995.

Dziak, RP, C.G. Fox, and AE Schreiner. The June-July 1993 Seismoacoustic Event at CoAxial Segment, Juan de Fuca Ridge: Evidence for a Lateral Dike Injection. Geophys Res. Lett., v:22, No. 2, 135-138, 1995.

Dziak, RP and C.G. Fox. Juan de Fuca Ridge T-wave Earthquakes August 1991 to Present: Volcanic and Tectonic Implications. Eos Transactions (abstract), American Geophysical Union, San Francisco, CA, v:76, No. 43, October 1995.

Kong, L.S.L., Dziak, RP, and C.G. Fox. Detection and Location of Hawaiian Earthquakes Using NE Pacific Military Hydrophone Arrays. Eos Transactions (abstract), American Geophysical Union, San Francisco, CA, v:76, N0.43, October, 1995

Koyanagi, S., K. Aki, N. Biswas, and K. Mayeda. Inferred Attenuation from Site Effect-Corrected T phases recorded on the Island Of Hawaii’i. Pure Appl. Geophys., v:144, 1-17, 1995.

Schreiner, AE, C.G. Fox, and RP Dziak. Spectra and Magnitudes of T-waves from the 1993 Earthquake Swarm on the Juan de Fuca Ridge. Geophys Res. Lett., v:22, No. 2, 139-142, 1995.


Fox, C.G., RP Dziak, H. Matsumoto, and AE Schreiner. Potential for Monitoring Low-level Seismicity on the Juan de Fuca Ridge Using Fixed Hydrophone Arrays. Mar. Tech. Soc., v:27, No. 4, 22-30, 1994.

Fox, C.G. and SR Hammond. The VENTS Program T-phase Project and NOAA’s Role in Ocean Environmental Research. Mar. Tech. Soc., v:27, No.4, 70-74, 1994.

Nishimura, CE and D.M. Conlon. IUSS Dual Use: Monitoring Whales and Earthquakes Using SOSUS. Mar Tech. Soc., v:27, No.4, 13-21, 1994.

Schreiner, AE and C.G. Fox. Comparisons of Ridge Crest Earthquake Waveforms Recorded on SOSUS Hydrophones with Ocean Bottom Seismometers in the Near-Field. J. Acous. Soc. Am.(abstract), v:95, No. 5, May, 1994.


Fox, C.G. , SR Hammond, and E.N. Bernard. Monitoring the Juan de Fuca Ridge Using US Navy Fixed Hydrophone Arrays. The Ocean Society (abstract), Seattle, WA, April, 1993.


Hiyoshi, Y., Walker, D.A., and C.S. McCreery, T-phase Data and Regional Tsunamigenesis in Japan, Bull Seism. Soc. Am., 54, 2085-2086.


Hammond, SR, and DA Walker, Ridge event detection: T-phase signals from the Juan de Fuca spreading center, Mar. Geophys. Res., v:13, 331-348, 1991.

Using data from MILS, ten times more earthquakes were recorded on ocean hydrophones than were reported by the global seismic network during the mid-1960's. Various radiators along the Juan de Fuca ridge are identified and are correlated with geological phenomena.

Keenan, R. E., and L.R.L. Merriam, Arctic abyssal T-phases: coupling seismic energy to the ocean sound channel via under-ice scattering, J. Acoust. Soc. Am., 89, 1128-1133, 1991.

Under-ice scattering is proposed to explain the generation of abyssal T-phases in the Arctic. It is also suggested that a similar mechanism (sea surface scattering) can generate abyssal T-phases in the open oceans.


McClelland, L., T. Simkin, M. Summers, E. Nielsen, T.C. Stein, Global Volcanism 1975-1985, Prentice-Hall, Inc., 1989.

This is a compilation of the Smithsonian Institution's Scientific Event Alert Network (SEAN) reports on volcanic activity from the years 1975-1985.

Talandier, J. Submarine volcanic activity: detection, monitoring, and interpretation, EOS, Trans. Amer. Geophys. Un., 70, 561, 568-569, 1989.


Smith, W.D., Underground nuclear explosions recorded at Raratonga examination of mb from T-phase amplitude, Geophys. J. R. astr. Soc., 90, 35-42, 1987

Talandier, J., and E.A. Okal, Seismic detection of underwater volcanism: the example of French Polynesia, Pure Appl. Geophys., 125, 919-950, 1987.

This is a comprehensive review on detecting underwater volcanism using seismometers in French Polynesia with numerous references to past work in other areas. A strong argument is made based on seismic observations that only shallow volcanic events produce T-phases.


Kadykov, I.F., Acoustics of Underwater earthquakes, Nauka, Moscow, 1986 (in Russian).

I have seen this book, but it certainly has the most interesting title. The author's name may be Kadydov.

Okal, E.A., And J. Talandier, T-wave duration, magnitudes and seismic moment of an earthquake: application to tsunami warning, J. Phys. Earth, 34, 19-42, 1986.

A theoretical model based primarily on empirical seismological relationships is presented which attempts to correlate T-phase duration and seismic moment. This simple model is then tested using a data set collected at Tahiti.


Cansi, Y., and N. Bethoux, T waves with long inland paths: synthetic seismograms, J. Geophys. Res., 90, 5459-5465, 1985.

Synthetic seismograms where the coupling of T- to P-phase is based on diffraction theory are generated and compared to observed T-phases. The basic conclusion reached is that the shape of the continental slope where the conversion takes place, plays a major role in the amplitude and duration of recorded T-phases.

Hall, L.H., Rumble IV seamount -- no rumble?, New Zealand J. Geol. Geophys., 28, 569, 1985.

A very short note pointing out that acoustic noise from Kibblewhite's Rumble IV seamount was probably from Rumble III. Furthermore, the apparent signal from Rumble III was probably shipping noise. Apparently the array geometry had been altered.

Hamada, N., T waves recorded by ocean bottom seismographs off the south coast of Tokai area, Central Honshu, Japan, J. Phys. Res., 33, 391-410, 1985.

This is a good paper which presents T-phase data recorded on permanent three-component OBS's. Because the receivers are geophones rather than hydrophones (i.e. wave polarization), and because the receivers are located off-shore (hence minimizing the contamination of the T-phase by propagation along a continental path), the authors are able to rigorously test past hypotheses about T-phases. One of their observations is that the particle motion for the T-phases is prograde elliptic in the vertical radial plane regardless if the receiver is above or below the axis of the SOFAR channel this represents motion of the lower boundary (sediment column) rather than motion of the water. A path dependency of the amplitudes is also shown (i.e. shallow water depths paths have smaller amplitudes). They are also puzzled about why T-phases should be dispersive.

Sereno, T., and J. Orcutt, Synthesis of realistic oceanic Pn wave trains, J. Geophys. Res., 90, 12755-12776, 1985.

While this paper is primarily about generating synthetic Pn wave trains, it does have a short section about the generation of abyssal T phases. The authors propose that abyssal T phases are water as well as crustal reverberations generated by postcritical P wave reflections off the Moho.

Walker, DA, and CS McCreery, Significant unreported earthquakes in "aseismic" regions of the western Pacific, Geophys. Res. Lett., 12, 433-436, 1985.

Po, So, and T-phases are used to identify various unreported earthquakes in the western Pacific. One rather anomalous unreported event produced large PO/So phases the estimated magnitude of this event is m = 5 to 6. Once again, the need for oceanic seismic/hydrophone stations is presented.

Walker, DA, CS McCreery, and F.J. Oliveira, Kaitoku Seamount and the mystery cloud of 9 April 1984, Science, 227, 607-611, 1985.

A month long earthquake swarm related to a shallow underwater volcanic eruption of Kaitoku Seamount, is recorded on the Wake Island hydrophone array (and also in Tahiti). Numerous T-phases are recorded. But what about the mystery cloud seen miles and miles away? Is it related to Kaitoku or is it the results of unknown evil forces?


Hall, L.H., A recent calendar of activity from Rumble III together with some related thoughts, Defence Scientific Establishment Technical Note 84/1, 1984.

I do not have this technical report which apparently has a major bearing on the results obtained by Kibblewhite (1966, 1967). Hall refers to this report in his 1985 short note.

Kadydov, I.F., Computation of underwater acoustic signals from an earthquake with due allowance for the ocean floor topography, Volc. Seism., 5, 207-212, 1984. (Translated from Vulkanol. i Seismol.)

Keenan, RE, and I. Dyer, Noise from Arctic Ocean earthquakes, J. Acoust. Soc. Am., 75, 819-825,1984.

T-phases recorded from a horizontal array of hydrophones deployed during the FRAM II experiment are hypothesized to have originated from earthquakes along the mid-Arctic ridge. The proposed mechanism for the generation of T is the scattering of acoustic signals from the base of the ice cover. The long duration of the observed T-phase is somewhat difficult to explain.

Talandier, J., and E.A. Okal, New surveys of Macdonald seamount, southcentral Pacific, following volcanoseismic activity, 1977-1983, Geophys. Res. Lett., 1, 813-816, 1984.

During 1977-1983, twelve seismic swarms at Macdonald seamount are detected by the French Polynesia seismic network using T-phases. The nature of the events indicate shallow volcanic activity. A bathymetric survey of Macdonald in 1982 indicates that the summit is shallower than when first surveyed by Johnson (1970).


Brocher, T.M., T-phases from an earthquake swarm on the Mid-Atlantic Ridge at 31.6°N, Mar. Geophys. Res., 6, 39-49, 1983.

T-phases from the Mid-Atlantic Ridge (31.6°N) are recorded on an OBS array deployed off Nova Scotia. The T-phase activity spanned a total of 30 hours in which 16 events were detected. Two of the events were located by the world-wide seismic network. Using the duration of the T-phase as a measure of the magnitude of the event, a b value of 1.2 is estimated for the swarm. A suggestion is made that ocean sensors might work better than the worldwide seismic network in detecting activity along mid-ocean ridges.

Ghalib, H.A.A., M. Barazangi, and B.I. Isacks, Excitation of T phases from shallow and intermediate-depth earthquakes in the southern Vanuatu (New Hebrides) Arc, Bull. Seism. Soc. Amer., 73, 1921-1928, 1983.

Ivashchenko, A.I., F.D. Zhuk, AI Spirin, R.R. Kharvi, and S.L. Pul, T-phases recorded by ocean-bottom seismographs near the junction of the Kuril and Japan Trenches, Seismological Studies of the World Ocean, ed. S.M. Zverev and S.A. Boldyrev, 87-93, 1983 (in Russian).


Talandier, J., and E. Okal, Crises sismiques du volcan Mac-Donald (Ocean Pacifique Sud), C.R. Acad. Sc. Paris, Serie II, 295, 195-200, 1982 (in French).

Sigh, another article written in French. This paper is about the seismicity of Macdonald Seamount during 1967-1981. Some of the results are presented in Talandier and Okal, 1984.

Walker, DA, Oceanic Pn/Sn phases: a qualitative explanation and reinterpretation of the T-phase, Hawaii Institute of Geophysics Report, HIG-82-6, 18 pp., 1982.

This paper proposes that abyssal T phases are generated by the coupling of Pn and Sn energy into the SOFAR channel. Note that in later references by Walker, Pn and Sn are renamed, PO and So.


Cansi, Y., Etude experimentale des ondes T, these de 3eme cycle, Univ. Paris XI, Orsay, 1981 (in French).

Once again I cannot read French, nor do I have a copy of this thesis. I assume that part of this thesis is presented in Cansi and Bethoux (1985).

Kadykov, I.F., Yu. S. Belavin, and U Ton II, T-phase radiation of earthquake signals by submarine flanks of the Kuril Islands, Vulkanol i Seismol., No. 4, 102-105, 1981 (in Russian).

I do not have this paper (which was referenced by Kadydov, 1984) as this journal was not translated into English at that time. This paper is apparently about T-phases observed in the Sea of Okhotsk. Note that the authors last name is spelled Kadykov in Russian, as oppose to Kadydov when translated into English.

Shapira, A., T phases from underwater explosions off the coast of Israel, Bull. Seism. Soc. Am., 71, 1049-1059, 1981.

T phases from underwater explosions are recorded on three land-base seismographs. Calculations are made on the quality factor Q, travel-time, and duration.


Katsumata, M., and K. Tokunaga, On the T-waves observed at Minamidaito-jima, Okinawa, Pap. Meteorol. Geophys., 31, 191-204, 1980 (in Japanese)

I do not have a copy of this paper nor can I read Japanese.

Okal, E.A., J. Talandier, K.A. Sverdrup, and T.H. Jordan, Seismicity and tectonic stress in the southcentral Pacific, J. Geophys. Res., 85, 6479-6495, 1980.

Most of this study is about what is stated in the title. This paper is included in the list because there is one short section on T-phases.

Solov'yev, SL, Y.S. Belavin, I.F. Kadykov, and U. Ton Il, T-phase recording in earthquake signals of the northwestern Pacific Ocean, Vulkanol. Seismol., 1, 60-69, 1980 (in Russian).


Adams, R.D., T-phase recordings at Raratonga from underground nuclear explosions, Geophys. J. R. astr. Soc., 58, 361-369, 1979.

T-phases from presumed underground nuclear detonations in French Polynesia are found to have generated large amplitude T-phases recorded at Raratonga. An estimate of the magnitude and yield of the explosions is derived using the duration of the signal, not the amplitude. Later arrivals representing reflections off of near-by seamounts are also observed.

Talandier, J., and E.A. Okal, Human perception of T waves: the June 22, 1977 Tonga earthquake felt on Tahiti, Bull. Seism. Soc. Am., 69, 1475-1486, 1979.

As previously demonstrated, the conversion of T to P-phases can result in the perception of an apparent local earthquake. The path dependency of this effect is also presented.


Denham, R.N., R.W. Bannister, K.M. Guthrie, and D.G. Browning, Underwater acoustic signals from a Kermadec Ridge earthquake, New Zealand J. Geol. Geophys., 21, 545-547, 1978.

P, S, and T waves are recorded on a hydrophone in the Fiji Basin from a Ms 6.9 earthquake in the Kermadec Trench (not the Ridge as stated in the title). The hydrophone was at a depth of 900 m and was deployed during an ambient noise experiment.

Walker, DA, CS McCreery, G.H. Sutton, and F.K. Duennebier, Spectral analyses of high-frequency Pn and Sn phases observed at great distances in the western Pacific, Science, 199, 1333-1335, 1978.

The quality factor, Q, for Pn and Sn (PO and So) in the Western Pacific are computed assuming that the spectrum of the source is given by the spectrum of observed T-phases. In some instances, the computed Q is abnormally high which leads to the hypothesis that the T-phase spectrum is somewhat attenuated.


Johnson, R.H., Possible submarine volcanic eruption off southern California, Deep Sea Res., 23, 265-267, 1976.

100 explosions were recorded in a 40 min time span on hydrophones located at Oahu, Midway, and Wake from a probable volcanic eruption off southern California. The shallowest seamounts in the calculated source region is on the order of 2000 m depth. However, the bathymetry is poorly constrained. (Note: would be nice to check more recent bathymetric maps for this region).

Talandier, J., and G.T. Kuster, Seismicity and submarine volcanic activity in French Polynesia, J. Geophys. Res., 81, 936-948, 1976.

Seismic activity from numerous sites in the vicinity of French Polynesia is monitored using a local array of seismometers several swarms resembling volcanic activity The presence or absence of T-phases for many of the events appears to depend on the propagation path (ie. obstacles). This paper also speculates whether one would expect T-phases from deep underwater volcanic events.


Shimamura, H., and T. Asada, T waves from deep earthquakes generated exactly at the bottom of deep trenches, Earth Planet. Sci. Lett., 27, 137-142, 1975.

In this paper, the authors propose that the T-phases that they observe are not SOFAR propagated waves but are instead multiply reflected signals. They do not mention possible normal-mode propagation.


Galanopoulos, A.G., And J.C. Drakopoulos, A T phase recorded on an accelerogram, Bull. Seism. Soc. Am., 64, 717-719, 1974.

This is the only published reference to a recording of T-phase on an accelerogram. The earthquake source is relatively close to the receiving instrument in Greece. The acceleration of the T-phase was only 0.02 g compared to a peak of 0.54g.

Gibowicz, S.J., J.H. Latter, and G.K. Sutton, Earthquake swarm associated with volcanic eruption, Curacoa Reef area, Northern Tonga, July 1973, Ann. Geofis., 27, 443-475, 1974.

This paper reports on a major earthquake swarm associated with an underwater volcanic eruption which occurred at Curacoa Reef. The character of the swarm appears to be divided into three distinct phases as constrained by changes in the computed b-values. T-phases were recorded on seismic stations seaward from the Tonga trench it is hypothesized that the source of the P to T conversion took place in the trench region. A compilation of ML versus T-phase amplitude as recorded at Afimalu indicates that the amplitude of the T-phase = 101.5ML

Northrop, J., T-phases from the Hawaiian earthquake of April 26, 1973, J. Geophys. Res., 79, 5478-, 1974.

T-phases from the large (m = 6.2) Hawaiian earthquake produced T-phases that were recorded on SOFAR hydrophones (MILS) at Wake, Midway, and Kaneohe. An interesting point is that no P wave arrival was recorded at the more distant stations. Also, reflections from several seamounts in the Gulf of Alaska were also recorded this is unusual for earthquakes while more common for explosive shots.

Northrop, J., Detection of low-frequency underwater sounds from a submarine volcano in the Western Pacific, J. Acoust. Soc. Am., 56, 837-841, 1974.

Data collected by the Pacific Missile Impact Location System indicate persistent acoustic activity from a region north of the Marianas Islands. It is proposed that it is associated with a shallow charted seamount and that the volcanic activity was explosive. Spectral banding observed for some of the events.


Johnson, R.H., Acoustic observations of nonexplosive submarine volcanism, J. Geophys. Res., 78, 6093-6096, 1973.

T-phases which exhibit spectral banding are used to infer that a seamount in the Marianas underwent a period of underwater volcanic activity. The volcanism is assumed to be nonexplosive as no visual indication of such an activity was observed in a populated island only 40 km away. There is some discussion concerning the acoustic source of "quiescent" underwater volcanism.

Northrop, J., T-phase radiation from the Cannikin explosion, J. Geophys. Res., 78, 1809-1817, 1973.

While the source was not an earthquake, this reference is included because it was an underground explosion (buried point source, initial coupling to the ground). The receivers used in this study are the SOFAR MILS hydrophones. The data show numerous precursors to the main T-phase which represent radiation (P to T) from sites between the source and the receivers. Numerous reflections from bathymetric features (e.g. seamounts) resulted in reverberations two hours after the main T-phase. Finally, the onset of the main T-phase was sharper than that from earthquakes in the Aleutians.

This paper is included in the T-phase reference list because it deals with the dispersion of acoustic waves in the SOFAR channel dispersion is also observed for T-phases.


Bath, M., and M. Shahidi, T-phases from Atlantic earthquakes, Pure Appl. Geophys., 92, 74-114, 1972.

This paper presents T-phase data from events primarily along the Mohns and Knipovich Ridges. There are some interesting results and conclusions reached. The primary one is that T-phases propagated primarily via surface-bottom reflections this is constrained by measured travel-times and by computed dispersion curves. The duration of the T-phase is also analyzed.

Johnson, R.H., And R.A. Norris, Significance of spectral banding in hydroacoustic signals from submarine volcanic eruptions: Myojin 1970, J. Geophys. Res., 77, 4461-4469, 1972.

Spectral analysis of T-phases from a confirmed volcanic event shows the presence of correlated spectral peaks with time. These peaks are not at constant frequency, but instead shift as a function of time. It is proposed that the spectral banding represents multiple water reverberations with the spectral banding caused by constructive interference of the reverberations. Confirmation of volcanic activity is given by observations made by a Japanese fishing boat of discoloration of the sea and also explosion felt on the boat.

Northrop, J. T-phases, in The Great Alaskan Earthquake of 1964: Oceanography and Coastal Engineering, 19-24, 1972.

T phases recorded on MILS from the 1964 Good Friday Alaskan earthquake and aftershocks are presented. The main shock produced T phases that lasted about 3 hours. The strongest T phases generated for the aftershocks were produced by earthquakes with hypocenters below the upper part of the continental slope (see Wadati and Inouye, 1955). This paper is a nice summary of T-phases.

Talandier, J. Etude et prevision Des tsunamis en Polynesie Francaise, These d' Universite, Universite Pierre-et-Marie Curie, Paris, 128 pp., 1972 (in French).

I cannot read an entire thesis written in French which is a mute point as I do not have a copy of this. However, I believe that there are considerable important points presented in the thesis.

Walker, DA, G.P. Woollard, G.H. Sutton, and J.J. LeTourneau, Easter Island seismograph observations indicative of sea-floor spreading, plate-edge seismicity relationships, and prediction of earthquakes along the west coast of the Western Hemisphere, Hawaii Institute of Geophysics Report, HIG-72-2, 25 pp., 1972.

In this technical report, some unusual data is reported which may be T-phases from events along the EPR.

Zhuk, FD, and SL Solov'yev, Possible recording of the hydroacoustic waves generated by earthquakes in the Pacific Ocean by the seismic stations of the USSR, in, Volny Tsunami


Johnson, R.H., R.A. Norris, F.K. Duennebier, and J. Northrop, T-phase data on Kamchatka/Kurils earthquakes: a reply, Bull. Seism. Soc. Am., 61, 791-794, 1971, with a reply by J.F. Evernden, pg 795.

This is your standard reply and counter-reply with both sides basically considering themselves correct. The discussion essentially boils down to one of the use and misuse of statistics.

Northrop, J., and M.F. Morrison, Underwater sound signals from the Amchitka Island underground and underwater explosions, J. Geophys. Res., 76, 1985-1992, 1971.

T-phase data from a 1-MT underground explosion (Milrow), a 340 T underwater detonation, and two earthquakes are analyzed. The results are used to determine criteria for discriminating between the three types of sources. In general, underground explosions and earthquakes are similar except for differences in the spatial extent and depth (attenuation of higher frequencies) of the source region. Differences between underwater and underground explosions are due to differences between direct and indirect (P to T conversion) coupling of the seismo/acoustic energy.


Evernden, J.F., T-phase data on Kamchatka/Kurils earthquakes, Bull. Seism. Soc. Am., 60, 1061-1076, 1970.

This paper is a critical analysis of the Duennebier and Johnson (1967), which attempts to explain discrepancies between the source location and origin time as computed by T-phase versus teleseismic data. The basic premise is that there can be virtual sources for the T-phases which are the result of focussing and defocussing of the acoustic energy due to the shape of the P to T source region.

Johnson, R.H., Estimating rupture length from T waves, in Tsunamis in the Pacific Ocean, Proc. of the International Symposium on Tsunamis and Tsunami Research, ed. W.M. Adams, 253-259, East-West Center Press, Honolulu, 1970.

The problem of determining the fault length of large earthquakes is presented along with a description of how an array of hydrophones at a single site might be able accomplish this task. The role of multiple radiation points as described by Johnson and Norris (1968) is also restated.

Johnson, R.H., And R.A. Norris, T-wave generation mechanisms, Hawaii Institute of Geophysics Report, HIG-70-7, 15 pp., 1970.

This the final report of the T-phase working group at the Hawaii Institute of Geophysics in which over 400 sonograms from T-phases located all over the Pacific are presented. A review of past work performed by this group is given with an emphasis placed on determining the mechanisms by which T-phases are generated. In general, it is conjectured that a varied combination of the contribution of differences in bottom-slope, bottom roughness, and sound velocity variations.

Johnson, R.H., Active submarine volcanism in the Austral Islands, Science, 167, 977, 1970.

Strictly speaking, this should not be listed with the T-phase papers since it about a bathymetric survey of Macdonald seamount. However, this is a classic paper about how to do science on one's vacation with the wife and kids, while still having lots of fun. In other words, get a sailing boat, get a echo sounder, load up the family, sail to Macdonald seamount, and do some science.

Norris, R.A., And D.N. Hart, Confirmation of SOFAR hydrophone detection of submarine eruptions, J. Geophys. Res., 75, 2144-2147, 1970.

T-phases from location of one of the five hypothesized volcanic eruptions in Norris and Johnson (1969), Farallon de Pajaros, is recorded on March 11 and 12, 1969 (the previous activity was in the spring of 1967). The T-phases display the same impulsive onset, high frequencies, and spectral banding of the 1967 event. By chance, in 1969, a Japanese tuna boat was in the immediate vicinity and noted three explosions and discoloration of the seawater which is highly indicative of a submarine volcanic eruption.

Northrop, J., Accuracy of earthquake epicenters on the Gorda Ridge, Bull. Seism. Soc. Am., 60, 265-267, 1970.

In this short note, the discrepancy between epicentral locations of earthquakes on (or near) the Gorda Ridge as calculated by T-phases versus P and S-P travel times is explained. In the former case, the epicenters are located on the ridge, while in the latter, they are located to the east of the ridge. As it turns out, Northrop is correct in his assessment that the body-wave locations are systematically incorrect due to azimuthally biased station coverage (i.e. poor station coverage to the west).


Auld, B., G. Latham, A. Nowroozi, and L. Seeber, Seismicity off the coast of Northern California determined from ocean bottom seismic measurements, Bull. Seism. Soc. Am., 59, 2001-2015, 1969.

In this paper, a brief mention is made to the recording of T-phases on an ocean bottom seismometer deployed in 4 km of water off San Francisco from earthquakes along the Mendocino Fracture Zone to the north. One comment is that the amplitude on the horizontal N-S component is larger than that on the E-W component.

Norris, R.A., And R.H. Johnson, Submarine volcanic eruptions recently located in the Pacific by SOFAR hydrophones, J. Geophys. Res., 74, 650-664, 1969.

T-phase data from the Pacific Missile Range network are used to identify five probable volcanic sources in the Pacific. The spatial distribution of the acoustic sources ranges from one in the Austral seamounts (this turns out to be Macdonald Seamount), two in the Marianas (Saipan and Farallon de Pajaros), one in the Aleutians (near Amilia), and one in Nanpo Shoto (Tori-shima). The primary discrimination tools which leads to a volcanic origin hypothesis are the similarity with shallow nuclear explosion (Amilia), impulsive onset (Farallon de Pajaros, Tori-shima, and Macdonald), spectral banding (Macdonald and Saipan), sharp peaked power spectrum of the T-phases indicative of magma-water interaction (?) (Farallon de Pajaros, Saipan, and Macdonald). See Norris and Hart (1970), and Johnson (1970) for more on Farallon de Pajaros and Macdonald.


Duennebier, F.K., Spectral variation of the T-phase, Hawaii Institute of Geophysics Report, HIG-68-22, 18 pp., 1968.

Spectrograms from various earthquakes are presented to illustrate spectral differences (high versus low frequencies) between abyssal and bottom-slope generated T-phases. Mechanisms for producing the variations in the different spectrograms are reviewed with the conclusion being that the source of abyssal T-phases is still a mystery i.e. sea-surface scattering is not the source of abyssal T-phases. The role of ocean acoustics is recognized in this paper.

Johnson, R.H., And R.A. Norris, T-phase radiators in the western Aleutians, Bull. Seism. Soc. Am., 58, 1-10, 1968.

T-phases from aftershocks of the 1965 Rat Island earthquake are used to illustrate that prominent submarine edifices can serve as radiation centers for T-phases. In this case, six radiation points corresponding to promontories along the Aleutian arc. An attempt is made to estimate the strengths of the various radiators. The duration of the main shock is also estimated with the caveat that one must take into account the contribution from the different radiation sites (note: the Rat Island earthquake was very large as was the fault length and the area of aftershocks).

Johnson, R.H., R.A. Norris, and F.K. Duennebier, Abyssally generated T-phases, in The Crust and Upper Mantle of the Pacific Area, edited by L. Knopoff, C.L. Drake, and P.J. Hart, AGU Mono. 12, 70-78, 1968.

A T-phase originating in the Aleutians generated a T-phases consisting of two components a high frequency component which has a source location similar to the computed epicenter, and a low frequency component similar in form to classic down-slope propagated T-phases which has a source location in the arc region. The low frequency wave is produced by propagation of P away from the receiving stations, towards the arc, and then converted to T by down-slope propagation. The high frequency component is termed an abyssal T-phase and is the result of scattering from the sea surface.

Northrop, J., An investigation of the relation between source characteristics and T phases in the North Pacific area, Ph.D. Thesis, University of Hawaii, 1968.

I do not have this thesis although there is a copy in the Hawaii Institute of Geophysics Library.

Northrop, J., Comments on a paper by J.B. Shepherd and G.R. Robson, The source of the T phase recorded in the eastern Caribbean on October 24, 1965, Bull. Seism. Soc. Am., 58, 743-744, 1968.

In this letter, it is argued primarily from a historical perspective, that the "true" definition of a T-phase requires that the source be an earthquake. I do not necessarily agree with this narrow definition otherwise one could not write about P or S phases from explosions.

Northrop, J., H.W. Menard, and F.K. Duennebier, Seismic and bathymetric evidence of a fracture zone on Gorda Ridge, Science, 161, 688-690, 1968.

T-phases from the Blanco Transform and Gorda Ridge fault are located by the Pacific Missile Range network of SOFAR hydrophones. Ironically, the location of the T-phase sources align themselves more closely on the Blanco Transform and Gorda ridge, than epicenters from the USCGS it is later learned that there is a systematic mislocation of epicenters in this area. Approximately 1000 T-phase events are located in this region with the majority of the events located at the bend in the Gorda Ridge. This study is a precursor to Hammond and Walker (1991).

Solovyev, SL, R.S. Voronin, and S.I. Voronina, Seismic and hydroacoustic data on T-waves (literature review), Tsunami Problem, Publ. House Nauka, Moscow, 141 pp., 1968 (in Russian).

I have not seen nor can I read this book. The title would indicate that it contains useful information. I am also not sure if the authors first name is spelled correctly (i.e. could by Soloviev). This paper is referenced by Bath and Shahidi (1972).


Cooke, R.J.S., Observations of the seismic T phase at Macquarie Island, New Zealand J. Geol. Geophys., 10, 1212-1225, 1967.

T phases from as far away as South America are reported a large number of events from the South Pacific Cordillera (aka Pacific-Antarctic Ridge and Southern East Pacific Rise) are also observed. Several interesting points are made in this paper. Earthquakes along the Macquarie Ridge (as reported by USCGS) do not generate T phases that are recorded on Macquarie Island possibly due to the presence of topographic barriers in the SOFAR channel. Secondly, T phases that reflected off of bathymetric features (i.e. Campbell Plateau) are recorded.

Duennebier, F.K., And R.H. Johnson, T-phase sources and earthquake epicenters in the Pacific basin, Hawaii Institute of Geophysics Report, HIG-67-24, 16 pp., 1967.

Two years worth of T-phase sources in the Pacific are identified in this technical report the total number exceeds 20,000 events. A comparison is made with the earthquake epicenters listed by the USCGS. It is shown that for various regions of the Pacific, T-phases are a better indicator of the seismic activity than the teleseismically determined epicenters.

Johnson, R.H., R.A. Norris, and F.K. Duennebier, Abssally generated T phases, Hawaii Institute of Geophysics Report, HIG-67-1, 12 pp., 1967.

See Johnson, Norris, and Duennebier (1968) for an equivalent reference.

Kibblewhite, A.C., Note on another active seamount in the south Kermadec ridge group, New Zealand J. SCI, 10, 68-69, 1967.

Another seamount (Rumble III) north of New Zealand is found to be active base on acoustic noise measurements. A fourth one, Rumble IV is really Rumble III as proposed in a later paper (Hall, 1985).

Norris, R.A., And R.H. Johnson, Submarine volcanic eruptions recently located in the Pacific by SOFAR hydrophones, Hawaii Institute of Geophysics Report, HIG-67-22, 16 pp., 1967.

See Norris and Johnson (1970) for an equivalent reference.

Shepherd, J.B., And G.R. Robson, 1967, The source of the T-phase recorded in the eastern Caribbean on October 24, 1965, Bull. Seism. Soc. Am., 57, 227-234, 1967.

High frequency T-phases recorded by short-period seismographs in the Caribbean is estimated to be from a shallow submarine volcano north of Grenada. It is proposed that collapsing steam bubbles are the acoustic source of this disturbance. An attempt is made to estimate the energy of the T-phases and to convert this number to energy produced by steam production. Some T-phases were felt on distant islands.


Johnson, R.H., Routine location of T-phase sources in the Pacific, Bull. Seism. Soc. Am., 56, 109-118, 1966.

A least-squares method for calculating the radiation location and origin time of T-phases is presented (see Johnson 1965 for an equivalent reference). The method used by HIG to compute T-phase magnitude is also presented (i.e. take second largest of four observations) the power of the T-phase is normalized to a prescribed distance (30° from the source). Velocity across the Pacific is described by a second order polynomial in latitude and longitude, spherical earth is assumed, four observations are used.

Johnson, R.H., And R.A. Norris, T-phase radiators in the western Aleutians, Hawaii Institute of Geophysics Report, HIG-66-4, 13 pp., 1966.

See Johnson and Norris (1968) for an equivalent reference.

Johnson, R.H., And J. Northrop, A comparison of earthquake magnitude with T-phase strength, Bull. Seism. Soc. Am., 56, 119-124, 1966.

Using the Pacific hydrophone network, 10 times more events are detected from the Aleutian Island region than that listed by the US Coast and Geodetic Survey. By comparing T-phase level is dB, S, with the observed earthquake magnitude, M, (when possible), a crude relationship can be formulated where, S = 20 M - 52. However, since many "large" T-phases are not recorded on the land-based seismometers, many events represent highly efficient excitation of T. Conclusions reached are that the use of T-phases extends the detection level of Aleutian earthquakes down 0.7 magnitude, and that there are as many event over and below M = 3.6 that can be located by T-phases.

Kibblewhite, AC, Detection and location of a new underwater volcano, Nature, 210, 938-939, 1966.

Short note on acoustic signals recorded from a possible underwater volcano (Rumble III) northeast of New Zealand. A better reference would be Kibblewhite, N.Z.J. SCI, 1966.

Kibblewhite, AC, The acoustic detection and location of an underwater volcano, New Zealand J. SCI, 9, 178-199, 1966.

Sea noise spectra recorded on hydrophones east of North Island, New Zealand, lead to the detection of underwater volcanic activity 150 miles ENE of Great Barrier Island. The spectra reveal a signal whose frequencies range from 20 to 400 Hz.

Kibblewhite, AC, and D.J. Barnes, The location of an underwater volcano by passive acoustic detection system, US Navy J. Underwater Acoust., 16, 353, 1966 (Confidential).

This paper is from a classified (confidential) journal which I have not seen. I assume that this article is similar to Kibblewhite (1966) except that it contains additional information about the instrumentation.


Anonymous, T-phase observer's manual, Hawaii Institute of Geophysics, 8 pp, 1965.

This is an in-house user's guide for analyzing T-phases at the Hawaii Institute of Geophysics.

Brazee, R.J., A study of T phases in the Aleutian earthquake series of March and April 1957, Earthquake Notes, 36, 9-14, 1965.

T-phases from Aleutian earthquakes are used to evaluate past hypotheses. The basic conclusions are that earthquake magnitude is not the sole determiner of T-phase generation, conversion from P to T can occur distant from the source, and that conversion to T is best when it occurs in the SOFAR channel.

Johnson, R.H., A program for routine location of T-phase sources in the Pacific, Hawaii Institute of Geophysics Report, HIG-65-6, 17 pp., 1965.

The technique for locating T-phase sources by means of triangulation is presented (See Johnson, 1966 for an equivalent reference).

Northrop, J., T phases from 80 Alaska earthquakes, March 28-31, 1964, Bull. Seism. Soc. Am., 55, 59-63, 1965.

This study describes T-phases from the main and aftershocks of the Good Friday Alaskan earthquake as recorded at Point Sur, California. It was observed that hypocenters (as determined by USCGS) for events located under the continent slope, were more efficient in generating T-phases this is more confirmation of the proposal of Wadati and Inouye (1953, 1956). Local topographic effects also contribute to the relative excitation of P to T conversion. Note: the T-phase from the main shock lasted 2 1/2 hours. See Northrop, 1972 for additional results.

Northrop, J., and R.H. Johnson, Seismic waves recorded in the north Pacific from Flip, J. Geophys. Res., 70, 311-318, 1965.

T phases from earthquakes and shots distributed along the margins of the Pacific (New Britain, Aleutians, and Hokkaido) are recorded by hydrophones suspended from Flip and also by the Pacific Missile Range network. Since T phase are recorded on hydrophones positioned at widely varying depths (e.g. 80 m for Flip, and 5500 m for Wake), it is concluded that T phase energy is not confined to the SOFAR axis (i.e. propagation by normal modes). There was also evidence of dispersion of the waves.

Wadati, K., and H. Sato, Propagation of T-waves in the Pacific Ocean, Geophys. Mag. Tokyo, 32, 255-271, 1965.

This paper is essentially a data dump of information pertaining to T-phases recorded at the Torishima seismic station from events around Japan, Chile, and Lituya Bay. Included are data recorded in Hawaii from the Chilean earthquakes. More credence is given to the notion that intermediate depth earthquakes are more effective in generating T-phases. On a side-note, the T-phase from one of the Lituya Bay earthquakes was felt in Japan.


De, US, Observations on T-phase, Ind. J. Meterol. Geophys., 15, 662-664, 1964.

Two more T-phases from the Andaman Island earthquakes are reported. Not much else to say about this paper.

Gupta, I.N., Discussion of "Source-mechanism from spectra of long-period seismic surface waves: 3. The Alaska earthquake of July 19, 1958" by A. Ben-Menahem and M.N. Toksoz, Bull. Seism. Soc. Am., 54, 2085-2086, 1964.

Correction to the equations used by Ben-Menahem and Toksoz are presented which results in a factor of two increase in the estimated duration time of the T-phase due to faulting. This new value is the same as the difference in the T-phase duration time of the main versus an aftershock. Northrop (1972) later shows that the equation used by Gupta is not applicable for T-phases measured on SOFAR hydrophones for the Good Friday Alaskan Earthquake.

Johnson, R.H., Earthquakes located by T phases during the VELA UNIFORM Aleutian Islands experiment, Hawaii Institute of Geophysics Report, HIG-64-23, 11 pp., 1964.

Earthquakes recorded on the Pacific Missile Range network of hydrophones during the VELA UNIFORM (essentially a calibration experiment in the Aleutians) are presented a total of 654 events were detected. It is estimated that the detection threshold of the hydrophone network is earthquake magnitude 3. This report is a precursor of the later work to be performed by Johnson and his co-workers at HIG.


Aubrat, J., Ondes T reflechies dans la Mer Des Antilles, Ann. Geophys.,19, 386-405, 1963 (in French).

T-phases observed on Martinique are presented along with a theory on the generation of T-phase from reflections off submarine slopes. I cannot read this paper, although I believe that it is an important one.

Ben-Menahem, A., and MN Toksoz, Source-mechanism from spectra of long-period seismic surface waves, 3. The Alaska earthquake of July 10, 1958, Bull. Seism. Soc. Am., 53, 905-919, 1963.

The authors used the duration of the observed T-phase to estimate the time of faulting of the Alaska earthquake. They attempt to take into account propagation effects by comparing the T-phase from the earthquake with that from a shot.

Johnson, R.H., Spectrum and dispersion of Pacific T phases, Hawaii Institute of Geophysics Report, HIG-34, 12 pp., 1963.

In this study, spectral analysis of T-phases indicates that the propagation velocity varies as a function of frequency.

Shaha, B.P, On T-phase at Visakhapatnam, Ind. J. Meterol. Geophys., 14, 89-91, 1963.

A T-phase from an earthquake close to Andaman Island is presented in one the more obscure references in this list. The authors suggest that the T-phase may be superimposed on the Rayleigh wave recorded at Madras.

Johnson, R.H., J. Northrop, and R. Eppley, Sources of Pacific T-phases, J. Geophys. Res., 68, 4251-4260, 1963.

This is the "introductory" paper of the Hawaii Institute of Geophysics as they begin to monitor T-phases in the Pacific using the hydrophones of the Pacific missile tracking stations. During the initial period of this study (12 days in March 1962), 81 apparent T-phases are observed 16 of the events were recorded on land-based seismic networks. Conclusions reached include support for down-slope propagation as the mechanism for generating T-phases, and the assertion that the computed radiation point of T-phases does not have to correlate with the source's epicenter.


Green, R., Tasmanian records of earthquake T phases from New Zealand, New Zealand J. Geol. Geophys., 5, 322-330, 1962.

Except for basically reiterating previous work on T-phases, this paper presents a list of T-phases recorded in Tasmania from earthquake sources in New Zealand. Mention is made of variations in the arrival of the T-phase at various stations in the seismic network.

Northrop, J., Evidence of dispersion in earthquake T-phases, J. Geophys. Res., 67, 2823-2830, 1962.

Spectral analysis of T-phases recorded by hydrophones indicate a frequency dependent propagation velocity (i.e. dispersion). It is noted that only the higher frequency T-phases propagate at the sound speed of water.

Shurbet, D.H., Note on use of a SOFAR geophone to determine seismicity of regional oceanic areas, Bull. Seism. Soc. Am., 52, 689-691, 1962.

The results for three years of observations at Bermuda indicate 10 times more events were detected on a SOFAR geophone than by a land-based short period Benioff seismometer. Author suggests that 'a geophone array could be more useful in determining regional seismicity in oceanic areas'.


Eaton, JP, DH Richter, and W.U. Ault, The tsunami of May 23, 1960, on the island of Hawaii, Bull. Seism. Soc. Am., 51-2, 135-157, 1961.

This article is primarily about the tsunami from the Chilean earthquake, but it has a section on the T-phases recorded in Hawaii. By comparing the amplitude and duration of T-phases from various foreshocks and the Mother of all recorded seismic events, it is concluded that the duration of the largest earthquake which produced the tsunami was seven minutes long (the dispersive nature of T-phases is not taken into account). The narrative section of the authors first-hand observations of the tsunami arrival in Hilo is absolutely spell-bounding.

Green, R., Appearance of the T-phase, Nature, 191, 997, 1961.

This paper is response to the called for assistance made by Robson and Barr (1960). Similar short period phases are observed in Tasmania, and their origin is subscribed to be T-phases.

Northrop, J., M. Blaik, and I. Tolstoy, Spectrum analysis of T-phases from the Agadir earthquake, US Navy J. Underwater Acoust., 11, 705, 1961 (Classified).

I do not have this paper as it is from a classified (confidential) Navy journal. I assume that it is similar to their 1960 paper except that it contains a lot more detailed information (like the location of the receivers).


Grinda, M.L., Nouveaux aspects Des ondes T, C. R. Acad. Sc. Paris, 250, 2241-2243, 1960 (in French).

This paper is apparently about the down-slope mechanism for generating T-phases.

Northrop, J., M. Blaik, and I. Tolstoy, Spectrum analysis of T phases from the Agadir earthquake February 29, 1960, 23h 40m, 12s GCT, 30° N, 9°W (USGCS), J. Geophys. Res., 65, 4223-4224, 1960.

Spectra of T-phases recorded on SOFAR-type bottom geophones indicate the presence of various acoustic modes. This paper is extremely sketchy (for instance the receiving stations are not identified, although Northrop's 1962 paper mentions that the recordings were done off the Bermuda Banks). They point out the frequencies of the T-phases are higher than 1 hz and hence land-based seismometers will not efficiently record the signals. They also mention that this is the rare recording of T-phases which propagated across the Mid-Atlantic Ridge.

Robson, G.R., And K.G. Barr, Unidentified earth tremors in Dominica, West Indies, Nature, 306, 1960.

Anomalous earthquakes characterized by a 0.3 sec period wave are observed on Dominica. The authors are quite puzzled by these apparent local earthquakes who have no apparent source the reason for this short note is a call for help. Well, you know the rest of the story (see Green, 1961).

Wadati, K., On the T phases observed at Torishima, Geophys. Mag. Tokyo, 30, 1-18, 1960.

Still more T-phase data is presented, this time that recorded on Torishima. Conclusions reached are intermediate depth earthquakes along subduction zones are better suited for generating T-phases, multiple reflections from various underwater obstacles are observed, and T-phases can be misinterpreted to be small local earthquakes. Finally, they also recorded a nuclear test explosion.


Khovanova, R.I., On T-phase and its possible relation to tsunami, Izv. Geophys. Ser., 1506-1509, 1959.

This is essentially a short review on T-phases. The conclusion reached is that T-phases arise from a variety of sources and hence, alone they will not be an adequate discriminator of tsunami genesis.

Milne, A., Comparison of spectra of an earthquake T-phase with similar signals from nuclear explosions, Bull. Seism. Soc. Am., 49, 317-329, 1959.

The dominant conclusions reached are that a sloping ocean bottom is required to efficient convert P waves to T waves, that the spectrum of P and T are similar, and that the duration of the signal from the nuclear explosion is shorter.


Shurbet, DH, and M. Ewing, T phases at Bermuda and transformation of elastic waves, Bull. Seism. Soc. Am., 47, 251-262, 1957.

T-phases recorded at Bermuda are used to investigate the conversion of various seismic phases (e.g. P, SV, and Lg) to the T-phase. It is shown that this conversion can take place at a large distance away from the earthquake epicenters. The azimuth of the propagation path for the P and T phases do not have to be the same in fact they can be going in the opposite directions. In this latter case, which they term PT*, the conversion from P to T is achieved by the advancement of the P phase from deep to shallower water. There are some interesting and weird points raised in this paper.


Wadati, K, and W. Inouye, On the T phase of seismic waves observed in Japan, in Proc. 8th Pacific Science Congress, II-A, 783-792, 1956.

This paper is extremely similar to the Wadati and Inouye (1954) as one might expect as this is a paper presented the Pacific Science Congress held in 1953.


Aubrat, J., and P. Molard, Secousses seismiques provoquees pas Des eruptons volcaniques sous-marines, Ann. Geophys., 11, 109- 113, 1955 (in French).

This is the second paper to present T-phases from an volcanic eruption although I have to admit that I did not actually read this paper.

Shurbet, DH, Bermuda T phases with large continental paths, Bull. Seism. Soc. Am., 45, 23-35, 1955.

This paper presents data which shows that T-phases with large continental paths are possible if the source to receiver path goes from continental to oceanic (i.e. South America to Atlantic Ocean). Several criteria need to be met for this to happen for the conversion of P to T including steep submarine slope at the transition point, and the magnitude and frequency of the P wave.


Baringth, M., A study of T phases recorded at the Kiruna seismograph station, Tellus, 6, 63-72, 1954.

This paper is interesting because it reports on T phases recorded from seismic events along the Mid-Atlantic Ridge north of Iceland (Mohns and Knipovich Ridges). A couple of the events occurred during the winter months when the SOFAR channel along parts of the propagation path, should be greatly narrowed or possibly eliminated due to lowering of sea-surface temperature. Simple derivation in this paper predicts that the amplitude ratio of the T and P waves is inversely proportional to the focal depth of the earthquake source.

Burke-Gaffney, T.N., The T phase from the New Zealand region, J. and Proc. Royal Soc N. S. Wales, 88, 50-54, 1954.

This is an interesting paper which analyzes T phases recorded in New Zealand. On the one hand, the author concludes that the corrected velocities of the T phases are greater than the velocity of sound in water but is less than the minimum value (i.e. 1.7 km/s) calculated by Leet et al. (1951). On the other hand, the author suggests that the velocity, as determined by the time of the maximum amplitude arrival, might be a better estimate of the true propagation time. This paper attempts to apply corrections based on the propagation of the T-phase through land, and also makes corrections for the source by considering when the phase enters the SOFAR channel (i.e. at the 700 fathom contour).

Byerly, P., and C. Herrick, T phases from Hawaiian earthquakes, Bull. Seism. Soc. Am., 44, 113-122, 1954.

T-phases from Hawaiian earthquakes for the years 1929-1952 are described it is noted that of 138 moderate to very strong quakes in Hawaii, only 10 gave rise to T-phases recorded on the Berkely seismic network. An interesting side note is that an apparent T-phase was first observed in 1936 and due to its short period, was classified as an unknown local earthquake (Byerly and Wilson, 1936).

Dietz, RS, and M.J. Sheehy, 1954, Trans-pacific detection of Myojin volcanic explosions by underwater sound, Bull. Geol. Soc. Am., 65, 941-956, 1954.

This a classic narrative of the first documented T-phase recordings of a distant volcanic eruption made by hydrophones. They reiterate the point initially raised by Ewing et al. (1946) that underwater hydrophones may be a valuable means of monitoring oceanic volcanic activity. This is the eruption that sank the Japanese research vessel, Kaiyo Maru.

Wadati, K., and W. Inouye, On the T phase of seismic waves observed in Japan, Geophys. Mag. Tokyo, 25, 159-165, 1954.

More data concerning T-phase observations are presented. An important conclusion drawn is that T-phase are larger if the epicentral distance of the continental slope is nearly equal to the depth of the hypocenter. This point is confirmed by later earthquakes which occur on the Alaskan trench (e.g. Northrop, 1972).


Ewing, M., and F. Press, Mechanisms of T wave propagation, Ann. Geophys., 9, 248-249, 1953.

In this short discourse, the authors present counterarguments to objections raised by Coulomb (1952) and Molard (1952) concerning T-phase propagation mechanisms.

Wadati, K., and W. Inouye, On the T phase of seismic waves observed in Japan, Proc. Japan Acad., 29, 47-54, 1953.

T-phases recorded in Japan and Tori-shima confirm the notion that a steep ocean bottom slope at the source leads to an effective generation of T-phases by the conversion of P or SV to T. Furthermore, it is proposed for the first time that T-phases will be more efficiently generated if the epicentral distance to the site of the P to T conversion is comparable to the focal depth of the earthquake. This point is confirmed by later studies (e.g. Northrop, 1972).


Biot, M., The interaction of Rayleigh and Stonely waves in the ocean bottom, Bull. Seism. Soc. Am., 42, 81-93, 1952.

A section at the end of this paper shows how Stonely waves can possibly excite T-phases (normal-mode coupling).

Coulomb, J., and P. Molard, Propagation Des ondes seismique T dan la Mer Des Antilles, Ann. Geophys., 8, 264-266, 1952 (in French).

I can not read this paper

Ewing, M., F. Press, and J.L. Worzel, Further study of the T-phase, Bull. Seism. Soc. Am., 42, 37-51, 1952.

First documented recordings of T-phases by ocean hydrophones (at the Point Sur SOFAR station) confirm the notion of Tolstoy and Ewing (1950) that the T-phase represents compressional wave transmission through the water column. They note that Leet et al. (1951) applied wrong travel-time corrections in taking into account transmission of P waves through the continent.

Molard, P., Remarques au sujet Des ondes T, Ann. Geophys., 8, 335-336, 1952 (in French).

This short note presents arguments that the computed travel-times of T-phases are not consistent with propagation through the oceans. The points raised are later refuted by Ewing and Press (1953).


Ewing, M., and F. Press, Propagation of earthquake waves along oceanic paths, Bu. Cen. Seism. Int'l., Volume title bound in: International Association of Seismology and the Physics of the Earth's Interior, Ser. A, 1951.

I do not have this paper.

Leet, L.D., Discussion of, "Proposed use of the T phase in tsunami warning system", Bull. Seism. Soc. Am., 41, 165-168, 1951.

First, let's quote verbatim two lines from the abstract. "Their statements about the characteristics of T are incorrect in every essential detail." ... "In the Atlantic, the proposal that T be used as a tsunami warning reduces to an absurdity." Used alone, T-phases are a poor predictor of tsunami generation although later papers will show that it may be used to estimate the rupture length of the earthquake.

Leet, L.D., D. Linehan, and P. Berger, Investigation of the T phase, Bull. Seism. Soc. Am., 41, 123-141, 1951.

This is a revaluation of the data used by Tolstoy and Ewing (1950) with the conclusion that T-phases are definitely not propagated through the water column (calculated propagation velocities are too high). Tentatively proposed that propagation of low velocity shear waves through sediments may be a better explanation.


Tolstoy, I. and W. M. Ewing, "The T-phase of shallow focus earthquakes", Bull. Seism. Soc. Am., 40, 25-51, 1950.


Coulomb, J., and P. Molard, Ondes seismiques au fond de la mar Des Antillas, Ann. Geophys., 5, 212-214, 1949 (in French).

The propagation velocity of T-phases recorded at Martinique in the Antilles for several earthquake sources are computed to have a mean value of 1.85 km/sec. They speculate that T-phases may represent Love waves propagating in ocean bottom sediments.


Brekhovskikh, L.M., Dokady Acad. Nauk, SSSR, 62, 469, 1948 (in Russian).

This paper, which I do not have, is referenced in Green, 1961. It is apparently about T-phases.

Ewing, M., and J.L. Worzel, Long-range sound transmission, in Propagation of Sound in the Ocean, GSA Memoir 27, 1948.

Classic treatise in a classic volume on some of the initial measurements made of long range sound transmission in the Atlantic Ocean the sources were explosives. They show that a source placed at the axis of the SOFAR channel can propagate with very little attenuation. Brief mention is made without explanation, of the potential use of water borne acoustic signals in monitoring underwater eruptions.

Perkeris, CL, Theory of propagation of explosive sounds in shallow water, in Propagation of Sound in the Ocean, GSA Memoir 27, 1948.

Another classic treatise in this classic volume which is included in this list because the theory presented has much bearing on normal-mode propagation of T-phases. Note, however, that the theory presented is for a liquid-liquid interface only.

Press, F., and M. Ewing, A theory of microseisms with geological applications, Trans. Am. Geophys. Union, 29, 163-174, 1948.

The theoretical work of Perkeris (1948) is extended to that of a liquid overlying a solid half-space. In terms of T-phases, this corresponds to normal-mode propagation.


Molard, P., Tremblements de terre Des Petites Antilles, et manifestations actuelles du volcanisme de l'archipel (1936 e 1943), Ann. Geophys., 3, 113-140, 1947 (in French).

I cannot read this paper, although it appears to be about volcanic activity in the Antilles. This paper is referenced in Shepherd and Robson (1967).


Ewing, M., GP Woollard, AC Vine, and J.L. Worzel, Recent results in submarine geophysics, Geol. Soc. Am. Bull., 57, 909-934, 1946.

In this review of the current state of the art of post-World War II marine geophysics, it is speculated that some underwater sounds recorded while performing an ocean acoustic experiment may have been from submarine volcanic activity. They point out that underwater volcanic activity can probably monitored by a network of SOFAR hydrophones.


Linehan, D., Earthquakes in the West Indian region, Trans. Am. Geophys. Union, 229-232, 1940.

This is the paper that coined the term T-phase (i.e. tertiary or third) for a signal that followed the primary (P) and secondary (S) seismic phases. No real explanation is given for its origin.

Ravet, J., Remarques sur quelques enregistrements d'ondes a tres courte periode au cours de tremblements de terre lointains a l'Observatoire du Faiere, Papeete, Tahiti, Sixth Pacific SCI Congress, vol 1, 127-130, 1940 (in French).

According to Talandier and Okal (1970), this was another case of an observed, but misinterpreted T-phase.


Byerly, P., and J.T. Wilson, Northern California earthquakes, April 1, 1934, to December 31, 1935, Bull. Seism. Soc. Am., 26, 207-213, 1936.

One of the first 'reported' observations of a T-phase although at the time, it was believed to have been from a small local earthquake. Later it was learned (see Byerly and Herrick, 1954) that the epicenter was in Hawaii the shock was felt in Franklin, California (Mercalli Intensity IV). The seismic signal was characterized by waves with a period of 0.5 s which was perplexing since the seismometers were supposed to be damped (suppress high frequencies).


Hawaiian Volcano Observatory, The Volcano Letter, 268, 1-4, 1930.

I do not have this paper. According to Talandier and Okal (1979), this is probably the earliest observation (not identification) of a T-phase.


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