Thousands of quakes hit Alaska since January's major shake
Apr. 13, 2018
KODIAK, Alaska (AP) — Thousands of small earthquakes have been recorded in the Kodiak area since a magnitude 7.9 temblor in January hit about 175 miles (281 kilometers) southeast of the city.
Nearly 3,000 aftershock quakes of 2.5 or above have hit since the major earthquake on Jan. 23. The vast majority have hit southeast of the island in the same area as the major quake, the Kodiak Daily Mirror reported Thursday. Only 20 were recorded last year over the same time period.
Natalia Ruppert, a seismologist at the University of Alaska, said aftershocks are expected to occur for months or even years. She said roughly 20 aftershocks are being recorded each day.
Kodiak is located northwest of the Aleutian Megathrust Fault, which is where the tectonic Pacific Plate subducts — or slips beneath — the North American Plate. There have been close to 50 quakes of 4.5 and higher in the area since Jan. 23. On March 27 and April 7, earthquakes of 5.4 and 5.2, respectively, were recorded.
The vast majority of the aftershocks were not severe enough to be felt, the Daily Mirror reported.
Although Ruppert said these earthquakes will subside eventually, it is not clear how long they will last.
"The frequency decreases, and the size of the aftershocks will decrease," she said. "A year from now, we'll probably see a couple of aftershocks a day and then couple of aftershocks a week."
Ruppert noted that in 1987 and 1988, there were two earthquakes of a similar magnitude to January's that took place in a similar location and occurred just months apart. In late November of 1987, an earthquake of 7.9 was recorded. That was followed by an earthquake of 7.8 in early March 1988. Both occurred in the northern Gulf of Alaska.
"They were a similar mechanism to what occurred in January," Ruppert said. "It is possible that this system of faults hasn't released all its stress yet."
Information from: Kodiak (Alaska) Daily Mirror, http://www.kodiakdailymirror.com