6.8 Magnitude Quake Shakes Alaska's Aleutian Islands

A 6.8 magnitude earthquake struck Alaska's Aleutian Islands early Friday morning, prompting an initial tsunami warning that was later canceled. The United States Geological Survey gave the quake a preliminary magnitude of 7.1 but later downgraded it to 6.8, which is a common occurrence after seismologists review data.

This quake was followed by smaller quakes in the same region that registered magnitudes between 3.9 and 4.8. The region where the quake occurred is sparsely populated and there have been no reports of actual damage from this quake.

The quake created a small wave that was seen in the community of Atka, located to the west of the temblor's epicenter but there was no damage reported and previous evacuation recommendations were canceled quickly. The 6.8 magnitude quake was registered at 1:55 a.m. local time and had a depth of 22.1 miles.

A slightly larger earthquake (magnitude 7.2) struck the Aleutians in the same area in June and also prompted a tsunami warning.

The earthquake was centered in the Fox Islands in the Aleutians in an area not far from the Cleveland volcano that showed an increase in eruptive activity in July and August. Cleveland is located on the uninhabited Chuginadak island in the Aleutians. The Alaska Volcano Observatory (AVO) first reported increased activity in Cleveland in late July and eventually raised the alert status as potential for eruption increased.

Currently, the alert status for Cleveland is at yellow for the aviation color code and advisory for the volcano alert status. This level was downgraded from orange/watch status on August 30 after it was determined that growth of the lava dome inside Cleveland had stopped or paused.

There is not a real-time seismic network near the Cleveland volcano, making it difficult to track seismic activity that may be related to volcanic activity in the region. Monitoring activity from Cleveland is usually via satellite and thermal imagery with visual observations from the air.

The AVO monitors volcanic activity in Alaska as well as some Russian volcanoes such as Kamchatka and volcanoes in the Kurile islands. The observatory is a joint program between the USGS, the State of Alaska Division of Geological and Geophysical Surveys (ADGGS) and the Geophysical Institute of the University of Alaska Fairbanks (UAFGI).

Tammy Lee Morris is certified as a Community Emergency Response Team (CERT) member and is a trained Skywarn Stormspotter through the National Weather Service. She has received interpretive training regarding the New Madrid Seismic Zone through EarthScope--a program of the National Science Foundation. She researches and writes about earthquakes, volcanoes, tornadoes, weather and other natural phenomena.