Update: The U.S. Tsunami Warning Centre cancelled the tsunami warning for the coastal areas of South Alaska, the Alaska Peninsula, and the Aleutian Islands as of 12:23 a.m. on July 22.

Original article:

A major offshore earthquake has struck south of the Alaskan Peninsula.

The quake struck at 11:12 p.m. PST today (July 21).

Although the U.S. Geological Survey initially assessed it as a 7.4-magnitude quake based on preliminary measurements, it was later reassessed as a 7.8-magnitude temblor.

The epicentre, located at a depth of 10 kilometres (six miles), was located 99 kilometres (61 miles) southeast of Perryville, Alaska; 121 kilometres (75 miles) south of Chignik, Alaska; and 846 kilometres (525 miles) southwest of Anchorage, Alaska.

Shaking has been reported felt in Anchorage.

The U.S. Tsunami Warning Centre has issued a tsunami warning that is in effect for South Alaskan and Alaska Peninsula coastlines, and the Aleutian Islands.

Anyone in these affected areas is asked to evacuate inland or to seek higher ground above and beyond tsunami hazard zones.

Tsunami sirens are sounding on the Alaskan coast, and residents along the Pacific coast of Alaska are reportedly evacuating to higher ground, including in Sand Point, Cold Bay, and Kodiak.

Boat operators are advised to move boats out to sea to a depth of at least 180 feet (55 metres) and to avoid entering shallow water.

After risk assessments, both Emergency Info B.C. and the U.S. Tsunami Warning Centre stated that there isn't a tsunami threat to British Columbia.

https://twitter.com/EmergencyInfoBC/status/1285839782061527042

Following the 7.8-magnitude quake, a succession of other earthquakes are occurring in the same area.

These quakes range from 3.9-magnitude to a 5.7- and a 6.1-magnitude temblor, according to the U.S. Geological Survey.