“This is a very unusual situation.“ : Swarm of Earthquakes in Alaska Puzzles Scientists

Alaska

A swarm of identical earthquakes has hit Alaska – taking place in the same low-seismicity area in the northwest, all at the same 5.7 magnitude.

No one in the Inuit Eskimo community in Noatak is used to earthquakes - there are no major active fault lines and the latest such incident took place back in 1981.

The area is about 100km north of the Arctic Circle. The April swarm struck about 30km from Noatak at a depth of about 16km. Just as with previous temblors, there were no injuries, apart from minor structural cracks in Noatak.

The regularity is a little bit offset. While the first two events happened in rapid succession on April 18, the third event did not happen until May 3. But all four were about the same magnitude, which is part of the reason the events are being treated as a group and called a “swarm” by Mike West, with the Earthquake Center.

Each event has since been accompanied by 300 smaller aftershocks, their magnitude reaching 3 at times. A 4.2 foreshock was also present this time, just before the main event hit. It was then followed by no less than 10 aftershocks.

USGS / 30 Days, Magnitude 2.5+ Worldwide

What is worrying to West is that the aftershocks are “unusually vigorous” and that the temblors “all have the same cause; the same fault motion” and “occur in more or less the same place.”

What is strange here is that unlike other strong aftershocks, these ones do not have a tendency to reduce in magnitude – they pulse in the same way.

Scientists so far have no answers as to what could have caused this.

“At this point, we don't really understand the nature of these earthquakes.”

The events are a huge mystery and researchers are on the ready for a larger earthquake; despite there being nothing to suggest it, events like this are usually followed by a much larger temblor.

“It’s a very tricky subject. This is a very unusual situation,” Herbert Walton told the newspaper. RT