A seismic map shows the epicenter and intensity of a major earthquake that struck off the eastern coast of Russia’s Kamchatka Peninsula on September 18, 2025, EDT. A powerful magnitude 7.8 aftershock off Russia’s Kamchatka Peninsula that arose from July’s magnitude 8.8 earthquake is raising concerns about possible tsunami impacts, although risk appears to be waningLess than two months after a magnitude 8.8 earthquake rocked Russia’s Kamchatka Peninsula, another strong earthquake occurred early on September 19 local time. USGS has already confirmed that the magnitude 7.8 event is an aftershock of the earlier earthquake, making it the latter quake’s largest aftershock to date. Both earthquakes occurred on the Kuril-Kamchatka plate boundary, which stretches from northern Japan, along the eastern coast of the Kamchatka Peninsula, toward the Aleutian Islands. The July earthquake spurred concerns of a serious tsunami but ended up not producing such a phenomenon because of local geology.