ALASKA VOLCANO OBSERVATORY DAILY UPDATE
U.S. Geological Survey
Tuesday, June 13, 2017, 2:00 PM AKDT (Tuesday, June 13, 2017, 22:00 UTC)

BOGOSLOF VOLCANO (VNUM #311300)
53°55'38" N 168°2'4" W, Summit Elevation 492 ft (150 m)
Current Volcano Alert Level: WATCH
Current Aviation Color Code: ORANGE

Last night a series of five explosive eruptions started at 17:47 AKDT June 12 (01:47 UCT June 13) and ended about 20:35 AKDT June 12 (04:35 UTC June 13). These events each lasted between 10 and 30 minutes and generated volcanic clouds that rose to a maximum height of 25,000 feet above sea level and dissipated within about 30 minutes. This sequence was detected in seismic, infrasound, and satellite data and a single lightning stoke was recorded. The Aviation Color Code was increased to RED and the Alert Level was raised to WARNING. This morning at at 8:17 AKDT (16:17 UTC) another short-duration (6-minute) explosion was detected in seismic and infrasound data. No ash cloud was observed in satellite imagery from this event likely because it was below our detection limits. The National Weather Service Alaska Aviation Weather Unit did not issue a SIGMET for this morning's event.

Earlier today, the Volcano Alert Level was lowered to WATCH, and the Aviation Color Code was lowered to ORANGE. Activity may ramp back up with additional explosions, either small and short-lived or longer and more voluminous, occurring with little or no precursory activity. Although we are able to detect energetic explosive activity in real-time, there is typically a lag of tens of minutes until we can characterize the magnitude of the event and the altitude of the volcanic cloud.

In addition to explosions that we can detect from nearby islands, It is possible for low-level unrest, including explosive activity, to occur that we are unable to detect with existing data sources. Such low-level periods of unrest and possible explosions could pose a hazard in the immediate vicinity of the volcano. During the day yesterday and prior to the evening's explosive activity, residents of Unalaska/Dutch Harbor reported smelling sulfur, and winds were consistent with a source at Bogoslof. This suggests ongoing degassing of shallow magma at the volcano.

AVO has no ground-based volcano monitoring equipment on Bogoslof volcano. We continue to monitor satellite images, information from the Worldwide Lightning Location Network pertaining to volcanic-cloud lightning, and data from seismic and infrasound instruments on nearby islands for indications of volcanic activity.

A Temporary Flight Restriction (TFR) is in effect over the volcano at the present time. Please see http://tfr.faa.gov/tfr2/list.html for the status of the TFR.

CLEVELAND VOLCANO (VNUM #311240)
52°49'20" N 169°56'42" W, Summit Elevation 5676 ft (1730 m)
Current Volcano Alert Level: WATCH
Current Aviation Color Code: ORANGE

Unrest continues. Elevated surface temperatures have been observed at the summit of Cleveland in two satellite images in the past day. No activity has been observed in seismic or infrasound data. Clouds obscured views by web camera..

Cleveland volcano is monitored with a limited real-time seismic network, which inhibits AVO's ability to detect precursory unrest that may lead to an explosive eruption. Rapid detection of an ash-producing eruption may be possible using a combination of seismic, infrasound, lightning, and satellite data.

PAVLOF VOLCANO (VNUM #312030)
55°25'2" N 161°53'37" W, Summit Elevation 8261 ft (2518 m)
Current Volcano Alert Level: ADVISORY
Current Aviation Color Code: YELLOW

No activity has been observed in seismic or infrasound data from the past day and clouds obscured satellite and web camera observations of the volcano.

The level of unrest at Pavlof can change quickly and progression to eruptive activity can occur with with little or no warning.

OTHER ALASKA VOLCANOES

Information on all Alaska volcanoes is available at : http://www.avo.alaska.edu.

For definitions of Aviation Color Codes and Volcano Alert Levels, see: http://www.avo.alaska.edu/color_codes.php

SUBSCRIBE TO VOLCANO ALERT MESSAGES by email: http://volcanoes.usgs.gov/vns/

FOLLOW AVO ON FACEBOOK: https://facebook.com/alaska.avo

FOLLOW AVO ON TWITTER: https://twitter.com/alaska.avo

CONTACT INFORMATION:

Michelle Coombs, Scientist-in-Charge, USGS
mcoombs@usgs.gov (907) 786-7497

Jeff Freymueller, Coordinating Scientist, UAF
jfreymueller@alaska.edu (907) 322-4085

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.

---