...Tectonic Summary
The July 29, 2025, M8.7 earthquake east of Petropavlovsk-Kamchatsky, Russia, occurred as the result of shallow reverse faulting. At the location of this earthquake, the Pacific plate is moving west-northwest with respect to the North America plate at about 77 mm/yr. Note, the North American plate extends westward beyond the North American continent. The earthquake's location and sense of motion is consistent with faulting on the subduction zone plate interface of the Kuril-Kamchatka Arc.
While commonly plotted as points on maps, earthquakes of this size are more appropriately described as slip over a larger fault area. Reverse faulting events of the size of the July 29, 2025, earthquake are typically about 130 km by 65 km in size (length x width).
The Kuril-Kamchatka arc has frequent moderate-to-large earthquakes and has hosted 31 additional M 6.5+ events within 250 km of the July 29, 2025, earthquake over the preceding century. This includes a M7.4 earthquake on July 20, 2025, which would now be considered a foreshock of the July 29, 2025, M8.7 event. The July 29, 2025, epicenter is located 45 km southeast of the 1952 M 9.0 Kamchatka earthquake epicenter, which resulted in a destructive, Pacific-wide tsunami. ...
