The Alaska Volcano Observatory has raised the threat level for the Pavlof Volcano due to increased seismic activity that could be the precursor of an eruption. The volcano, which is about 625 miles southwest of Anchorage, erupted on March 27, sending an ash cloud 37,000 feet high, causing the cancellation of flights. The last eruption was in mid-May.
The volcano has erupted more than 40 times since the late 1700s, which was the beginning of record-keeping. According to the observatory, Pavlof can erupt in episodes that cover long periods of time. It erupted intermittently from April 1986 to August 1988, with only pauses in seismic activity.
The observatory found increasing seismic activity on Thursday, and web camera images on Friday showed minor steam emissions. The aviation advisory color went from green to yellow.
Pavlof is Alaska’s most active volcano. Since the March eruption it has repeatedly shown seismic activity. Geophysicist Dave Schneider says the activity is normal. “Pavlof is one of those volcanoes that can erupt without very much in the way of precursory activities,” Schneider said. “It’s very easy for the magma to arise in the volcano and make it out. So even subtle signs of unrest we think it is prudent to increase our alert level.”
The activity is not a definite sign of an impending eruption, but it is the beginning of what an eruption can look like. Scientists are looking for tremors that last longer and grow stronger. The temperature of the volcano will also be monitored, and small explosions watched for.
Photo credit: NASA