A tsunami warning was issued after a powerful earthquake hit Alaska's southern coast.
The M 7.5 earthquake struck on Monday, October 19, 2020, at around 9 p.m. UTC time, 91 kilometers southeast of Sand Point, a city in Aleutians East Borough, southern Alaska.
The temblor's epicentral depth was around 40 kilometers. It occurred on a strike-slip fault situated near the subduction zone between the North American Plate and the Pacific Plate. The size of similar magnitude strike-slip faulting incidents covers an area of about 130x25 kilometers.
In the region where the seismic shock occurred, the Pacific Plate is subducting under the Alaska-Aleutian Trench and converges with the North American Plate at a rate of 64 millimeters per year. According to the United States Geological Survey (USGS), the current incident was an aftershock of the M 7.8 seismic event that hit Alaska in July 2020.
A tsunami warning was immediately issued for multiple communities along the coastline of Alaska. Residents living in coastal areas had to get to higher ground in order to remain safe.
According to Scott Langley, associate with the National Tsunami Warning Center, two tsunami waves were indeed generated. Each one measured around 1,3 meters in height. Nevertheless, local witnesses mentioned observing waves between 45 and 61 centimeters. The strongest waves hit Sand Point and more remote coastal towns were less affected. The warning was canceled on the evening of the same day.
Locals reported feeling the strong earthquake but, fortunately, there were no casualties or injuries associated with the event. "We are getting very accustomed to these earthquakes, and I've learned to just accept that this is what we have to endure when we decide to live between volcanoes and an active plate, the ring of fire," Candace Nielsen, a local, stated.
In terms of infrastructure impact, buildings have withstood the seismic shock. No severe damage has been reported in the coastal areas affected. "Everything seemed to be intact", Gary Hennigh, King Cove city administrator, said.
A M 5.2 seismic shock followed about 10 minutes after the main incident. More than 25 aftershocks (measuring from M 3.5 to M 5.9) have been reported and experts believe that the seismic sequence will continue.
Alaska is an earthquake-prone region. In 1964, the strongest earthquake ever recorded in U.S. history occurred in the Prince William Sound region of Alaska. The M 9.2 seismic shock lasted for 4,5 minutes triggering massive tsunamis and causing structural damage, eventually resulting in 131 casualties.
In 2018, the region of Anchorage was hit by a powerful M 7.0 temblor that prompted severe infrastructure damage but fortunately, causing no casualties.