U.S. Dept. of Commerce / NOAA / OAR / PMEL / VENTS Program

Axial Seamount Volcanic Event, January, 1998

NeMO Cruise Website (education/public outreach) News from sea: Ron Brown at Axial (& completed ALVIN cruise news) (posted 8/7/98) 1998 Cruises at Axial (posted 7/17/98) Results from WECOMA Includes Preliminary Science Results Seismic Information Wecoma Response Cruise General Description of Axial Volcano Related Sites NOAA VENTS Program Acoustic Monitoring Project Ocean Seismicity Theme Page NSF RIDGE Program R/V WECOMA Pacific Northwest Earthquake Information

Beginning at 1200 GMT on 25 January 1998, intense seismicity was detected in the northeast Pacific Ocean using the T-phase Monitoring System developed by NOAA/PMEL to access the U.S. Navy's SOund SUrveillance System (SOSUS). The initial activity was located on the summit and southern flank of Axial Seamount on the central Juan de Fuca Ridge near 45 55'N and 130 00'W, approximately 300 miles west of Cannon Beach, Oregon. The seismic activity lasted twelve days and included over 8,000 earthquakes detected by SOSUS. The character of the seismicity is very similar to that observed at CoAxial Segment and the Northern Gorda Ridge, both episodes that were later confirmed to be eruptive events. Volcanic seismicity is distinctive in having numerous small events that arise from the ambient noise without a large mainshock. The initial level of activity for this event was greater than either the CoAxial or Gorda Events. All U.S. Navy SOSUS arrays and NOAA recording systems were operational and an excellent data set showing the initiation and early migration of activity was analyzed. Thanks to all personnel at NOPF Whidbey Island. A response effort was organized by NSF/RIDGE and NOAA/VENTS investigators. A short expedition using the Oregon State University research vessel WECOMA occurred February 9-16 (preliminary results available). Other research expeditions to Axial Volcano are planned for mid-summer 1998 aboard the NOAA Ship Ron Brown.

Listing of past daily updates

Address inquiries to:

Event Detection

Bob Dziak - Seismologist - dziak@pmel.noaa.gov

Event Response
Jim Cowen - University of Hawaii - jcowen@soest.hawaii.edu
Bob Embley - NOAA/PMEL