A 6.3-magnitude earthquake was reported in Alaska on Sunday (December 8), according to the United States Geological Survey.
The earthquake was centered in Adak at a depth of 47.9 kilometers (about 30 miles). The USGS said it received one report of a person having felt the earthquake at the time of publication.
The Alaska earthquake was reported two days after a 4.0-magnitude earthquake was reported in California on Friday (December 6), according to the United States Geological Survey. The earthquake was centered in Petrolia at a depth of 0.6 kilometers (about 0.37 miles).
The 4.0-magnitude earthquake was reported hours after a 7.0-magnitude earthquake was reported in Petrolia on Thursday (December 5). The Thursday earthquake was centered at a depth of 0.6 kilometers (about 0.37 miles) and the USGS said it received 16,318 reports of people having felt it as of Friday.
A tsunami warning was issued for the San Francisco Bay Area by the National Weather Service but was called off shortly after. The USGS also reported a 2.5-magnitude earthquake in French Gulf, California, and a 2.5-magnitude earthquake in Cobb, California, at the same time as the Petrolia earthquake.
A 4.4-magnitude earthquake was also reported in the same city on Wednesday, according to the United States Geological Survey. The earthquake was centered in Petrolia at a depth of 10.0 kilometers (about 6.2 miles).
The California earthquakes were reported days after a 6.1-magnitude earthquake was reported in Japan on November 26, according to the United States Geological Survey. The earthquake was centered in Hakui at a depth of 10 kilometers (about 6.2 miles).