Map: 7.8-Magnitude Earthquake 7.8 Off Russia Prompts Tsunami Advisory in Alaska | USAEMALL.com

A major, 7.8-magnitude earthquake struck in the North Pacific Ocean on Thursday, according to the United States Geological Survey. The earthquake prompted a tsunami advisory, the second-highest alert level, for some coastal portions of western Alaska.

The temblor happened at 2:58 p.m. Eastern about 80 miles east of Petropavlovsk-Kamchatsky, Russia, data from the agency shows.

The tsunami advisory was in place for parts of the Alaskan coast that were closest to the earthquake.

Tsunamis are a series of long waves caused by a large and sudden displacement of water in the ocean, usually from a large earthquake on or below the ocean floor. Tsunamis radiate in all directions from the epicenter and can cause dangerous coastal flooding and powerful currents that can last for hours or days.

The Pacific Tsunami Warning Center in Honolulu said it was too soon to tell whether tsunami waves might threaten Hawaii, noting that the earliest any threat might reach the islands would be 2:51 p.m. local time.

In late July, the same region was hit by an 8.8-magnitude earthquake. That quake, one of the strongest ever recorded, set off tsunami waves that reached as far away as Hawaii and California.

As seismologists review available data, they may revise the earthquake’s reported magnitude. Additional information collected about the earthquake may also prompt U.S.G.S. scientists to update the shake-severity map.