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Alaska Volcano Observatory

Alaska Volcano ObservatoryWeekly UpdateFriday, October 10, 2008 1:59 PM AKDT (21:59 UTC)

KASATOCHI VOLCANO (CAVW #1101-13-)
52°10'9" N 175°30'41" W, Summit Elevation 1030 ft (314 m)
Current Aviation Color Code: YELLOW
Current Volcano Alert Level: ADVISORY

Seismicity at Kasatochi remains low. Clouds obscured views of the volcano by satellite most of the week. During partly clear viewing periods, a weak thermal anomaly was observed, likely from the warm crater lake and/or the slowly cooling, recently erupted volcanic deposits.

Kasatochi Volcano does not have a seismic network, thus AVO depends on networks on neighboring islands to monitor earthquake activity there. For this reason, low-level seismicity may not be detected and renewed volcanic activity is possible at any time with little or no warning.

Kasatochi Island represents the emergent summit of a predominantly submarine volcano composed of basaltic and andesitic lava flows and pyroclastic deposits. The island consists of a single cone with a central circular crater with a diameter of 1.4 km. The maximum height of the crater rim is about 314 m. The volcano's most recent eruption began on August 7, 2008. This eruption produced ash clouds as high as 50,000 ft above sea level and pyroclastic-flow and surge deposits that cover the entire island to a depth of many meters. Prior the 2008 eruption, Kasatochi had no confirmed historical activity, although it is possible that eruptions attributed to nearby Konuiji volcano in 1760, 1827, and 1828 were actually minor eruptions of Kasatochi. Eruptive activity in 1899 may have destroyed a lake within the Kasatochi crater. Kasatochi is 83 km (52 mi) east of the community of Adak , and 90 km (55 mi) west of the community of Atka.

CLEVELAND VOLCANO (CAVW #1101-24-)
52°49'20" N 169°56'42" W, Summit Elevation 5676 ft (1730 m)
Current Aviation Color Code: UNASSIGNED
Current Volcano Alert Level: UNASSIGNED

On Thursday October 9, AVO downgraded the Aviation Color Code for Cleveland Volcano to UNASSIGNED and the Alert Code to UNASSIGNED. Because Cleveland is not monitored with real-time seismic instrumentation, we do not assign it green or normal, because the absence of unrest cannot be confirmed.

AVO monitors Cleveland Volcano with satellite imagery as weather allows. The lack of a real-time seismic network at Cleveland prevents AVO from tracking local earthquake activity related to volcanic unrest. Short-lived explosions of ash that could exceed 20,000 ft above sea level can occur without warning and may go undetected on satellite imagery. Cleveland volcano forms the western half of Chuginadak Island, a remote and uninhabited island in the east central Aleutians. It is located about about 75 km (45 mi.) west of the community of Nikolski, and 1500 km (940 mi.) southwest of Anchorage.

OKMOK VOLCANO (CAVW #1101-29-)
53°23'49" N 168°9'58" W, Summit Elevation 3520 ft (1073 m)
Current Aviation Color Code: YELLOW
Current Volcano Alert Level: ADVISORY

Low-level seismicity at Okmok Volcano continues. Satellite views of the volcano were mostly cloudy this week; no activity was observed. A few clear to partly cloudy satellite views this week showed nothing unusual.

Although the level of seismicity is relatively low, it is possible for vigorous ash emissions to resume at any time.

Okmok volcano is a 6-mile-wide caldera that occupies most of the eastern end of Umnak Island, located 75 miles southwest of Dutch Harbor in the eastern Aleutian Islands. Okmok has had several eruptions in historic time typically consisting of ash emissions occasionally to over 30,000 feet ASL but generally much lower; lava flows crossed the caldera floor in 1945, 1958, and 1986. The nearest settlements are Nikolski, population about 35, roughly 45 miles west of the volcano, and a small number of people at Fort Glenn, 10 miles east of the volcano.

OTHER ALASKA VOLCANOES

Seismic activity is monitored in real time at 31 volcanoes in Alaska. Satellite images of all Alaskan volcanoes are analyzed daily for evidence of ash plumes and elevated surface temperatures. Some volcanoes may currently display anomalous behavior but are not considered to be at a dangerous level of unrest. Augustine, Iliamna, Redoubt, Wrangell, Gareloi, Great Sitkin, Makushin, Fisher, Shishaldin, Isanotski, Pavlof, Veniaminof, Ugashik-Peulik, Griggs, Snowy, Fourpeaked, Aniakchak, Tanaga, Kanaga, Akutan, Westdahl, Dutton, Ukinrek Maars, Martin, Mageik, Trident, Katmai, Novarupta, Spurr, and Korovin volcanoes are in color code GREEN and volcano alert level Normal. All are at or near normal levels of background seismicity. AVO did not detect ash plumes or significant elevated surface temperatures in the vicinity of any volcano.

Please see http://www.avo.alaska.edu/color_codes.php for complete definitions of Aviation color codes and Volcano alert levels.

VOLCANO INFORMATION ON THE INTERNET: http://www.avo.alaska.edu
RECORDING ON THE STATUS OF ALASKA'S VOLCANOES (907) 786-7478

CONTACT INFORMATION:
Tom Murray, Scientist-in-Charge, USGS
tlmurray@usgs.gov (907) 786-7497

Steve McNutt, Coordinating Scientist, UAF
steve@giseis.alaska.edu (907) 474-7131

The Alaska Volcano Observatory is a cooperative program of the U.S. Geological Survey, the University of Alaska Fairbanks Geophysical Institute, and the Alaska Division of Geological and Geophysical Surveys.

CASCADES VOLCANO OBSERVATORY WEEKLY UPDATE
Friday, October 10, 2008 12:13 PDT (Friday, October 10, 2008 19:13 UTC)

MOUNT ST. HELENS VOLCANO (CAVW#1201-05-)
46.20°N 122.18°W, Summit Elevation 8363 ft (2549 m)
Volcano Alert Level: NORMAL
Aviation Color Code: GREEN

The 40-month-long lava-dome eruption of Mount St. Helens that began in autumn 2004 ended in late January of this year. Earthquakes, volcanic gas emissions, and ground deformation are all at pre-eruptive background levels. The alert level and aviation color code were reduced to NORMAL/GREEN on July 10, 2008, following five months with no sign of renewed activity.

Even with the end of lava dome growth, some hazards persist. The new lava dome remains hot in places and capable of producing small hot avalanches or minor explosions that could dust areas with ash up to tens of miles downwind. Rock fall from the crater walls can produce clouds of dust that rise above the crater rim, especially during dry, windy days, as has happened in the past. Also, heavy rainfall or rapid snowmelt can send small debris flows onto the Pumice Plain north of the crater.


Recent observations:
Volcano seismicity at Mount St. Helens and elsewhere has remained quiet over the past week. Given the onset of wet weather, and snow at higher elevations, this has also been a quiet week for field work in the Cascades. The only significant field activity has been reoccupation of campaign GPS sites in the vicinity of the Three Sisters.





The U.S. Geological Survey and University of Washington continue to monitor these volcanoes closely and will issue additional updates and changes in alert level as warranted.

For additional information, background, images, and other graphics: http://vulcan.wr.usgs.gov
For seismic information on Oregon and Washington volcanoes: http://www.pnsn.org/WEBICORDER/PNSN/welcome.html
For seismic information on California volcanoes: http://earthquakes.usgs.gov/eqcenter/recenteqsus/Maps/special/California_Nevada.php
For a definition of alert levels: http://vulcan.wr.usgs.gov/Volcanoes/Cascades/CurrentActivity/volcano_warning_scheme.html
For a webcam view of Mount St. Helens: http://www.fs.fed.us/gpnf/volcanocams/msh/
Telephone recordings with the latest update on Mount St. Helens and phone contacts for additional information can be heard by calling: (360) 891-5180.

HAWAIIAN VOLCANO OBSERVATORY DAILY UPDATE
Friday, October 10, 2008 07:35 HST (Friday, October 10, 2008 17:35 UTC)

KILAUEA VOLCANO (CAVW#1302-01-)
19.42°N 155.29°W, Summit Elevation 4091 ft (1247 m)
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; tephra production continues from the Halema`uma`u vent. Lava flows through tubes to the ocean west of Kalapana.

Last 24 hours at Kilauea summit: Plume direction yesterday was to the southwest and south. Glow from the Halema`uma`u vent overnight was again episodic and bright but again weaker than previous nights; the lava pond is probably relatively high in the vent but still well below the rim. This morning, the plume is rising over the Ka`u Desert to the southwest of the vent. At 7 am, the plume was moving SSW before fanning to the south in GOES-WEST imagery.

Sulfur dioxide emission rates remained elevated and variable. The most recent average measurement was 900 tonnes/day on October 6, compared to the 2003-2007 average rate of 140 tonnes/day.

The Halema`uma`u vent continued to produce tephra dominated by glassy fragments. We retrieved another small set of samples this morning.

Kilauea caldera continues to deflate. The summit tiltmeter network recorded weak tilting inward toward Halema`uma`u crater. The GPS receiver networks (less sensitive than tiltmeters) recorded weak contraction.

Seismic activity continued to be focused on Halema`uma`u Crater; episodic tremor has weakened considerably since Oct. 8. Two moderate hybrid earthquakes occurred yesterday and this morning. A total of 11 earthquakes were located beneath Kilauea or nearby, including 3 beneath the south caldera and 5 on south flank faults, with a decreasing number of RB2S2BL earthquakes (less than 50/day).

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 1,200 tonnes/day on October 3 is below background levels for this vent over the past 25.5 years. No incandescence was observed within the crater overnight.

Pu`u `O`o continues to deflate. The tiltmeter on the north side of Pu`u `O`o recorded tilting inward toward the crater. GPS stations spanning the crater (less sensitive than tiltmeters) recorded no significant extension or contraction. Seismic tremor levels near Pu`u `O`o and the TEB vent were at low values.

Lava from the TEB vent and the complex of rootless shields is flowing through tubes to the ocean. HVO geologists mapped four breakouts from the Waikupanaha tube that have been active over the past few days, three of which started above the pali and flowed mostly to the east (see map). The Waikupanaha ocean entry was active but weak yesterday. CD officials reported multiple glowing points above the pali along with multiple ocean entry points last night. GOES-WEST thermal anomalies were present until 2:30 am suggesting that either the surface breakouts are no longer active or that they have been beneath clouds. No incandescence was observed from the east rift eruption site to the top of the pali above the subdivision. CD officials report a good, strong plume and rainy conditions this morning.

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
Friday, October 10, 2008 09:05 PDT (Friday, October 10, 2008 16:05 UTC)

LONG VALLEY VOLCANIC CENTER VOLCANO (CAVW#1203-14-)
37.70°N 118.87°W, Summit Elevation 11122 ft (3390 m)
Volcano Alert Level: NORMAL
Aviation Color Code: GREEN

The realtime computer system did not detect any earthquakes in the vicinity of Long Valley caldera since the last update at 10:32 AM (PDT) on Thursday October 9.

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The Long Valley Observatory (LVO) monitors and studies earthquakes, ground deformation, degassing, and other types of geologic unrest in and around the Long Valley Caldera. The 15 by 30 km Long Valley Caldera was formed during an eruption 760,000 years ago and is located 20 km south of Mono Lake along the east side of the Sierra Nevada in east-central California. There have been multiple smaller eruptions since the caldera-forming eruption with the most recent occurring 250 years ago in Mono Lake at the north end of Mono-Inyo Craters volcanic chain. LVO is one of the five USGS Volcano Observatories that monitor volcanoes within the United States for science and public safety.

Report prepared by the U.S. Geological Survey.

There have been no reports of eruptive activity of Anatahan this week.


During times of northerly winds, the Anatahan plume, if present, could be directed towards the CNMI and Guam. If this happens, residents may notice hazy air conditions and smell sulfur. The Emergency Management Office (EMO) of the CNMI government will issue volcanic haze and sulfur advisories if appropriate.

Access to the island may be restricted by the CNMI government. Contact the EMO to get the latest information.

YELLOWSTONE VOLCANO OBSERVATORY MONTHLY UPDATE
Wednesday, October 1, 2008 11:42 MDT (Wednesday, October 1, 2008 17:42 UTC)

YELLOWSTONE VOLCANO (CAVW#1205-01-)
44.43°N 110.67°W, Summit Elevation 9203 ft (2805 m)
Volcano Alert Level: NORMAL
Aviation Color Code: GREEN

SEPTEMBER 2008 Yellowstone Seismicity Summary

During the month of September 2008, 62 earthquakes were located in the Yellowstone region. The largest event was a magnitude 2.9 on September 25 at 12:07 PM MDT, located about 16 miles southeast of West Thumb, YNP, and near the southern caldera boundary. This event was part of a swarm of 19 events with magnitudes 0.9 - 2.9.

Earthquake activity in the Yellowstone region is at normal background levels.

Ground Deformation Summary: Through September 2008, continuous GPS data show that much of the Yellowstone caldera continued moving upward, though at a lower rate than the past several years. The maximum measured ground uplift over the past 50 months is ~21 cm at the White Lake GPS station. An example can be found at: http://pboweb.unavco.org/shared/scripts/stations/?checkkey=WLWY&sec=timeseries_plots&timeseries=raw

The general uplift of the Yellowstone caldera is scientifically interesting and will continue to be monitored closely by YVO staff.

An article on the current uplift episode at Yellowstone and discussion of long-term ground deformation at Yellowstone and elsewhere can be found at: http://volcanoes.usgs.gov/yvo/2007/upsanddowns.html

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The Yellowstone Volcano Observatory (YVO) is a partnership of the U.S. Geological Survey (USGS), Yellowstone National Park, and University of Utah to strengthen the long-term monitoring of volcanic and earthquake unrest in the Yellowstone National Park region. Yellowstone is the site of the largest and most diverse collection of natural thermal features in the world and the first National Park. YVO is one of the five USGS Volcano Observatories that monitor volcanoes within the United States for science and public safety.