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Five Restless and Erupting Alaska Volcanoes Keep Scientists Busy

July 25, 2014

Composite false-color Landsat-8 satellite image of Semisopochnoi Island on July 14, 2014, produced by combining the shortwave infrared, near infrared, and visible wavelength data. This color combination enhances the visualization of vegetation, exposed rocks, and snow (light blue). This is a rare, partly cloudy satellite image and some of the volcanic features are indicated. The image does not show evidence of increased surface temperatures in response to the increased number of volcanic earthquakes that began in early June 2014. For information about Ladsat8 see the website: http://landsat.usgs.gov/index.php. (USGS)

The following is this week’s edition of “Volcano Watch” from the USGS Hawaiian Volcano Observatory.

Do you want to know which volcanoes in the United States are erupting? Or which volcanoes are showing signs of activity which may lead to an eruption? You can find answers to these questions at the website of the U.S. Geological Survey’s Volcano Hazards Program: http://volcanoes.usgs.gov. The home screen features a map display of current levels of activity for nearly 170 volcanoes with links to more information about them and their current activity.

Better yet, you can sign in at the website for the Volcano Notification Service (VNS) to receive automatic email notifications when there is a change in the level of activity at all U.S. volcanoes or in one or more of the following locations: Alaska, California, the Cascades of Washington and Oregon, Hawaiʻi, Yellowstone, and the Northern Marianas Islands.

The VNS will also send you information statements prepared by scientists for active volcanoes when the level of activity has not changed significantly. You’ll receive regular updates issued daily, weekly, bi-weekly, or monthly, releases about a volcano’s status, changes in monitoring capabilities, potential eruption scenarios, or general commentary about a volcano.

Screenshot from http://volcanoes.usgs.gov/ showing current volcanic activity in the United States and its territories. (USGS)

Screenshot from http://volcanoes.usgs.gov/ taken this morning showing current volcanic activity in the United States and its territories. (USGS)

This service was made possible by the adoption in 2006 of a unified alert-level system by all U.S. volcano observatories, and in 2010 of a central database-driven system for preparing the notifications and sending them via email to key users and stakeholders. The VNS became publicly available in 2012, and there are now about 7,500 subscribers around the world.

In early June, the map showed five volcanoes in Alaska with elevated alert levels indicating eruption or elevated activity—the highest number of volcanoes that scientists of the Alaska Volcano Observatory (AVO) had to track closely and issue notifications and warnings at the same time.

Also shown on the map were activity levels for Pagan Volcano in the Northern Marianas Islands and the ongoing eruption of Kīlauea Volcano on the Island of Hawaiʻi.

The most vigorous eruption in early June was occurring at Pavlof Volcano, one of the most frequently active volcanoes in Alaska, located about 1,000 km (620 miles) southwest of Anchorage. Lava fountaining at the summit generated ash plumes as high as 9 km (30,000 ft) above sea level that extended as far as 80-90 km (50-60 miles) downwind. Lava spatter that accumulated near the vent occasionally collapsed to form hot, lava-rock avalanches down the volcano’s ice- and snow-covered north flank, generating steam plumes and meltwater. Spatter-fed lava flows also moved down the north flank.

Composite satellite image of Pavlof Volcano showing the extent of the lava flows on the northeast flank. The base image was collected by the Worldview-2 satellite on May 9, 2014 (prior to the onset of eruptive activity) and is overlain (in color) with a Landsat-8 thermal infrared image collected early in the morning on June 24, 2014. The thermal infrared sensor measured the heat given off by the still-warm lava flow. The length of the longest branch of the lava flow is about 5 km (3 miles). Note that the lava flow appears to have traveled under the ice on the upper flank of the volcano. (USGS)

In mid-June AVO scientists increased the alert level for Semisopochnoi volcano for the first time when they detected an earthquake swarm that started on June 9. Fortunately, the radio telemetry system for seismic stations monitoring the volcano was repaired about two weeks earlier! Earthquake activity remains elevated this week.

Semispochnoi Island consists of many cones and volcanic landforms, including an 8-km-wide caldera (5 miles), located about 2,200 km (1350 miles) southwest from Anchorage. The most recent eruption occurred in 1987 when an ash cloud was observed in satellite imagery. There are several reports of Semisopochnoi producing “smoke” between 1792 and 1873 from one or more of its cones.

The other Alaskan volcanoes with elevated activity levels in June included Shishaldin, with a low-level eruption, and Cleveland and Veniminof volcanoes, with elevated seismic activity and thermal features.

All of this activity required even more than the usual vigilance by AVO scientists to track the eruptions and unrest using monitoring networks, satellite data, and observations. They are ever watchful for signs that a hazardous explosive eruption is imminent or underway, using the VNS to report on the status of the volcanoes to the world.

For more information about volcanic activity in Hawaii, be sure to visit the Hawaiian Volcano Observatory.

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