ALASKA VOLCANO OBSERVATORY INFORMATION STATEMENT
U.S. Geological Survey
Tuesday, June 18, 2013, 6:16 PM AKDT (Wednesday, June 19, 2013, 02:16 UTC)
56°11'52" N 159°23'35" W,
Summit Elevation 8225 ft (2507 m)
Current Volcano Alert Level: WATCH
Current Aviation Color Code: ORANGE
The current eruption of Veniaminof volcano continues, with the effusion of a lava flow from the intracaldera cone in the summit caldera, and occasional, short-lived emissions of volcanic ash. Over the past day, the lava flow has grown in size, and now extends for about 1600 ft (500 m) down the slope of the cone and onto the adjacent snow and ice field. Ash emissions have been observed in web camera data from Perryville (about 35 km to the southeast) during periods of clear weather, and several emissions from this afternoon have produced diffuse ash clouds that were transported beyond the crater rim. Although these ash clouds have been observed in web camera and by ground observers, they have not been associated with a definitive seismic signal as only two of the seven stations on the volcano are operational, and have been too small to be detected in satellite images. So far, the ash emissions have been rising a few thousand feet above the top of the cone and have not likely exceeded 15,000 feet above sea level.
Veniaminof volcano is frequently active with five eruptions in the last 30 years.
Chronology of Events
Volcanic tremor was first observed at Veniaminof beginning about June 6. The ongoing volcanic tremor is similar in character and amplitude to tremor observed during other small eruptions of Veniaminof since 2000. We have not observed earthquakes or explosions large enough to have been detected by regional infrasound monitoring during the current eruption. Thus, geophysical monitoring data suggests that this eruption is proceeding in a similar manner to small recent eruptions. Satellite data obtained over the past several days indicates that trace amounts of ash fall have occurred within the caldera only.
Elevated surface temperatures were detected in satellite data on June 13 and continue to be seen. This signal is consistent with the effusion of lava at the vent.
History and Prognosis
The present eruption of Veniaminof Volcano is thus far similar to previous historical eruptions in 2002, 2004-2006 and 2008. In each of these eruptions, minor amounts of ash fall (<1/4 inch) occurred but accumulations of ash were confined to the caldera ice field and upper flanks of the volcano. Lava flows were produced during eruptions in 1983-84 and 1992-93, but lava did not extend much beyond the intracaldera cone and did not result in known outflows of water from the Cone Glacier area into the Muddy River valley to the north.
At this time AVO has no evidence to indicate that the present eruption will differ significantly from previous historical small eruptions. Minor emissions of steam and ash are expected to continue, perhaps for several weeks or more. The lava flow also may continue to grow in size, but is not expected to flow much beyond the base of the intracaldera cone and should not result in any unusual hydrologic events in drainages surrounding the volcano. It is possible for water to become ponded within the caldera and if released rapidly, the Muddy River could experience a temporary rise in water level, which might be noticeable in the area downstream from the snout of Cone Glacier on the north side of the volcano. There is a small possibility that activity at Veniaminof could ramp up without much warning.
Although we maintain some ability to seismically monitor the volcano, our capability is diminished compared to prior eruptions, as only two out of seven seismic stations in the network are functioning reliably. One of the currently disabled stations clearly showed small ash emissions, similar to those observed today, during the most recent eruption in 2004 and 2005. However given the current state of the network, we are not able to detect these explosions in real-time with seismic data. Thus we are dependent on good viewing conditions, a webcam operated by the FAA, and satellite data to detect these explosions. Unlike real-time seismic data, satellite data can have a delay of 30-60 minutes. Although we cannot seismically observe small ash emissions that have occurred so far, we do expect to detect a large ash emission seismically, should one occur.
AVO is monitoring the activity at Veniaminof closely and will be reporting at least once daily on the status of the volcano. Additional information will be made available on the AVO web page (www.avo.alaska.edu) when necessary.
VOLCANO INFORMATION ON THE INTERNET: http://www.avo.alaska.edu
RECORDING ON THE STATUS OF ALASKA'S VOLCANOES (907) 786-7478
John Power, Scientist-in-Charge, USGS
firstname.lastname@example.org (907) 786-7497
Jessica Larsen, Acting Coordinating Scientist, UAFGI
email@example.com (907) 474-7992
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.