7.8 quake off Kamchatka triggers Pacific tsunami alerts

A powerful earthquake struck off Russia's Kamchatka Peninsula on Thursday, Sept. 18, registering 7.8 magnitude according to the U.S. Geological Survey, and prompted tsunami advisories for parts of the North Pacific including Alaska as officials assessed the threat to Hawaii and other Pacific coastlines. The quake was centered roughly east of the city of Petropavlovsk-Kamchatsky and occurred at a shallow depth, raising concerns about tsunami generation in the seismically active Kuril-Kamchatka Arc.

Preliminary USGS data placed the epicenter about 80 to 128 kilometers east of Petropavlovsk-Kamchatsky, with a depth reported near 10 kilometers. Russian authorities initially reported a lower magnitude of 7.2, and some early reports gave different depth estimates, underscoring routine variance in immediate seismic measurements. The governor of Kamchatka, Vladimir Solodov, said on Telegram that residents were being alerted and that there were no immediate reports of damage.

U.S. tsunami-warning agencies moved quickly. The National Oceanic and Atmospheric Administration issued a tsunami advisory and two watches for portions of Alaska, including parts of the Aleutian Islands, and the...