Recent Volcano Observatory Activity Reports
HAWAIIAN VOLCANO OBSERVATORY DAILY UPDATE issued Sep 16, 2008 07:50 HST Volcano Alert Level WATCH - Aviation Color Code ORANGE
This report on the status of Kilauea volcanic activity, in addition to maps, photos, and webcam images (available using the menu bar above), was prepared by the USGS Hawaiian Volcano Observatory (HVO). Hawai`i Volcanoes National Park status can be found at http://www.nps.gov/havo/ or 985-6000. Hawai`i County Viewing Area status can be found at http://www.lavainfo.us or 961-8093.
Activity Summary for last 24 hours: Sulfur dioxide emission rates from both the Halema`uma`u and Pu`u `O`o vents remain high, returning trade winds are again blowing the gases to the southwest. Lava continues to flow through tubes originating at the east rift eruption site and is entering the ocean west of Kalapana.
Last 24 hours at Kilauea summit: Strengthening trade winds blew the plume southwest high over the Ka`u Desert through slightly hazy air; the plume turned brown with fine ash at least five times yesterday; nearby observers reported that each ashy plume was preceded by a loud sound. Glow from the Halema`uma`u vent overnight was a little stronger, possibly due to clearer viewing conditions. This morning, the plume is rising inclined to the south before turning to the southwest about 300 m (1,000 ft) above the Ka`u Desert. GOES-WEST imagery shows the plume extending SSW from the vent and going offshore near Ka`aha at 6:30 am.
This morning's tephra collection yielded significantly larger amounts, possibly due to the returning trade winds and the unusually large number of ashy plumes. The tephra consists mostly of glassy fragments in various shapes.
Sulfur dioxide emission rates remained elevated and variable. The most recent average measurement was 800 tonnes/day on September 11, compared to a pre-2008 background rate of 150-200 tonnes/day.
The summit tiltmeter network and GPS stations spanning the summit caldera recorded no significant inflation or deflation.
Seismic tremor has been at steady moderate levels but the number of earthquakes under Kilauea increased. Sixteen earthquakes were located beneath Kilauea or nearby, including 7 beneath the southern summit caldera and two on south flank faults. The number of RB2S2BL earthquakes beneath Halema`uma`u Crater was on the rise again to values above 80/d (background less than 40/d).
Last 24 hours at the middle east rift zone vents and flow field: Magma continues to degas through Pu`u `O`o Crater. The most recent sulfur dioxide measurement of 1,700 tonnes/day on September 8 is near background levels for this vent over the past 25.5 years. No incandescence was observed within the crater overnight.
The tiltmeter on the north side of Pu`u `O`o recorded deflation over the past week with an oscillation this morning that appears like inflation. GPS stations spanning the crater continued to record contraction. Seismic tremor levels near Pu`u `O`o and the TEB vent remained at low levels.
Lava from the TEB vent and the complex of rootless shields continued to flow through tubes to the ocean. No incandescence was observed from the rift zone to the top of the pali above the abandoned Royal Gardens subdivision overnight. No thermal anomalies are visible in the GOES-WEST satellite imagery suggesting yesterday's surface flow activity was small and temporary.
Definitions of terms used in the update:
DOH air quality monitoring: see Hawai`i State Department of Health Air Quality website http://hawaii.gov/doh/air-quality/index.html .
bomb: lava fragment ejected into the air while molten acquiring aerodynamic shapes in flight; the term is restricted to pieces larger than 6.4 cm (2.5 in.). See http://volcanoes.usgs.gov/Products/Pglossary/bomb.html
hybrid, or explosion, seismic signals: complex earthquakes that are a hybrid of different signals. They start as a high frequency earthquake, similar to typical rock-breaking or rock fall events, that transitions to very long, 20-30 second, period (VLP) oscillations that continue for several minutes. At HVO, we observed these signals with the four small Halema`uma`u explosive eruptions in March, April, and August 2008. Several more similar signals, some as strong as the explosion signals associated with the four explosive eruptions, have been recorded without obvious evidenceof surface eruption such as rock fragments or other debris.
MODIS satellite: a NASA satellite pair, Aqua and Terra, which passes over Hawai`i twice a day. During daylight hours, the images are taken at about 11 am and 2 pm H.s.t. This imagery can be viewed about 3-5 hours after acquisition at http://rapidfire.sci.gsfc.nasa.gov/subsets/?subset=AERONET_Mauna_Loa.
GOES-WEST satellite: a geostationary NOAA satellite used most often for weather tracking. Images are typically acquired every 15 minutes. The loop http://www.ssd.noaa.gov/VAAC/kilauea/sloop-vis.html is posted by the Washington DC Volcanic Ash Advisory Center for the purpose of tracking emissions from Hawai`i volcanoes. The imagery automatically switches from infrared at night to visual during the day. Recently, it has been useful for tracking volcanic gas emissions from Halema`uma`u, Pu`u `O`o, and the Waikupanaha ocean entry during the day and hot lava flows at night.
Volcano Watch: weekly newspaper-like article written by HVO scientists on a volcano topic of interest. These articles are usually printed in the Sunday editions of the Hawai`i Island newspapers Hawaii Tribune Herald and West Hawaii Today. More than 800 of these articles have been written and are archived on the HVO website (menu at the bottom of the homepage hvo.wr.usgs.gov).
VLP seismic tremor: seismic tremor is continuous ground vibrations simultaneously at many different frequencies. VLP is a very long period or very low frequency component which, at the Halema`uma`u vent, has a period of 20-30 seconds or a frequency of 0.03-0.05 cycles per second (Hertz or Hz).
RB2S2BL earthquakes: earthquakes that were recorded but too small to be located. These quakes have magnitudes less than 1.7 and may only be recorded on one or two seismometers. Recording at a minimum of 4 seismometer sites is required to locate an earthquake.
wink: an abrupt shutting off of incandescence at a vent lasting for several minutes. At the Halema`uma`u vent, winks usually start with or immediately follow a small, local earthquake. The diminishment of incandescence is due to the plume changing from translucent to opaque with rock dust.
tonne: metric unit equal to 1,000 kilograms, 2,204.6 lbs, or 1.1 English tons.
microradian: a measure of angle equivalent to 0.000057 degrees.
ppm: parts-per-million; 10,000 ppm = 1 %.
littoral cone: usually small cones built near active ocean entries; the cones are constructed of tephra from steam explosions that are sometimes produced when 1,150 degree C lava enters the 25 degree C ocean.
incandescence: the production of visible light from a hot surface. The color of the light is related to the temperature of the surface. Some surfaces can display dull red incandescence at temperatures as low as 430 degrees Centigrade (806 degrees Fahrenheit). By contrast, molten lava displays bright orange to orange-yellow light from surfaces that are hotter than 900 degrees C (1,650 degrees F).
tephra: all material deposited by fallout from an eruption-related plume, regardless of size.
ash: tephra less than 2 mm (5/64 inches) in size.
TEB: Thanksgiving Eve Breakout, the designation used for lava flows that started with a breakout on November 21, 2007.
DI tilt event: DI is an abbreviation for 'deflation-inflation' and describes a volcanic event of uncertain significance. DI events are recorded by tiltmeters at Kilauea summit as an abrupt deflation of up to a few microradians in magnitude lasting several hours to 2-3 days followed by an abrupt inflation of approximately equal magnitude. The tilt events are usually accompanied by an increase in summit tremor during the deflation phase. A careful analysis of these events suggests that they may be related to changes in magma supply to a storage reservoir at less than 1 km depth, just east of Halema`uma`u crater. Usually, though not always, these changes propagate through the magma conduit from the summit to the eruption site, as many of the DI events at Kilauea summit are also recorded at a tiltmeter at Pu`u `O`o, delayed by 1-2 hours. DI events often correlate with lava pulses and/or pauses in the eruption at the Pu`u `O`o/July 21/TEB vents.
Maps, photos, webcam views, and other information about Kilauea Volcano are available at http://volcano.wr.usgs.gov/kilaueastatus.php. A daily update summary is available by phone at (808) 967-8862.
A map with details of earthquakes located within the past two weeks can be found at http://tux.wr.usgs.gov/
A definition of alert levels can be found at http://volcanoes.usgs.gov/2006/warnschemes.html LONG VALLEY OBSERVATORY CURRENT STATUS REPORT issued Sep 16, 2008 09:39 PDT Volcano Alert Level NORMAL - Aviation Color Code GREEN
One magnitude M=1.9 earthquake was detected in the vicinity of Long Valley caldera since the last update at 10:13 AM (PDT) on Monday September 15. The event was located outside the caldera in the Sierra Nevada SW of Round Valley. Cleveland Status Report issued Sep 15, 2008 11:34 ADT Volcano Alert Level ADVISORY - Aviation Color Code YELLOW
Clouds obscure Cleveland volcano in satellite and web camera views. AVO received no reports of activity at the volcano. Okmok Status Report issued Sep 15, 2008 11:34 ADT Volcano Alert Level ADVISORY - Aviation Color Code YELLOW
Seismicity at Okmok volcano continues at low levels. Satellite views were cloudy today.
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