KLYUCHEVSKOY volcano in eastern Russia erupted just a day after a magnitude 8.8 earthquake jolted the Kamchatka Peninsula. The reports were first released by the Geophysical Center of the Russian Academy of Sciences.
The explosion validates scientific studies of the interrelation of seismic activities in the far eastern Russian territory. According to a US Geological Survey (USGS) bulletin, Russian scientists found a lava lake on Klyuchevskoy’s summit last July 21 and were expecting an eruption very soon.
The ash plume from the eruption reached about 1.5 miles (2.5 kilometers) above and 36 miles (58 km) east of the volcano. Experts warned that ash explosions up to 5 miles (8 km) high could occur at any time.
SEISMIC EVENTS Left photo from IVSFE-RAS shows the magnitude 7.0 earthquake on Aug. 17, 2024, triggered the eruption of the Shiveluch volcano two days later. The Klyuchevskoy volcano (right photo) in eastern Russia erupted hours after an 8.8-magnitude Kamchatka earthquake. PHOTO BY ALEXANDER PIRAGIS FROM LIVESCIENCE.COM
July 30’s magnitude 8.8 megathrust earthquake at Kamchatka had a similar seismic activity pattern — a foreshock and a volcanic explosion nearly a year earlier.
This is one of the strongest earthquakes recorded globally in over a decade, in what is known as the Pacific Ring of Fire. Scientists from the Russian Academy of Sciences (RAS) are closely examining the relationship between this colossal tremor and a series of previous powerful seismological events.
Volcano first
The region was rattled by a magnitude 7.0 earthquake on Aug. 17, 2024, which, according to the Institute of Volcanology and Seismology of the Far Eastern Branch of the RAS (IVSFE-RAS), triggered the eruption of the Shiveluch volcano two days later. Shiveluch, one of Kamchatka’s most active, ejected ash plumes that soared hundreds of kilometers into the sky. Right after that explosion, scientists already predicted that a magnitude 9.0 earthquake was to follow “anytime soon,” with one information bulletin saying, “within 24 hours.”
Foreshock
On July 20, 2025, a magnitude 7.4 earthquake, followed by a magnitude 6.8 tremor two days later, both happened near Petropavlovsk-Kamchatsky. Geologists at the IVSFE-RAS said in a bulletin that events appear to have been foreshocks, hinting at the immense strain building within the Earth’s crust that ultimately culminated in the 8.8-magnitude temblor.
“The earthquake that occurred just off the Kamchatka peninsula is a large magnitude event and occurred on a subduction zone where the Pacific Plate is diving down under the Okhotsk Plate, and because it was offshore, it generated a tsunami,” explained Professor John Townend, an earthquake scientist and professor of geophysics at Victoria University of Wellington.
The Kuril-Kamchatka subduction zone is a highly active geological boundary, moving at a rate of approximately 77 millimeters per year. It is known as a generator of megathrust earthquakes and associated tsunamis.
More historical quakes
“The subduction zone moves in segments, and today’s earthquake seems to have occurred between the segments that ruptured in 1952 and an earlier great event in 1923. Further work is needed on how this affects the stress regime, but certainly many aftershocks are expected, and are occurring,” Dr. Roger Musson, Honorary Research Fellow of the British Geological Survey (BGS) said in a Science Media Center bulletin.
There were two earthquakes in 1924, the first one in February that generated a tsunami 8 meters (26 feet) tall. The second shaker happened in April and killed over 2,000 people in Japan with tsunamis as high as 30 meters (98 feet).
Megathrust and seismic gaps
Assessments from both the USGS and the IVSFE-RAS suggest that the 8.8-magnitude earthquake filled a “seismic gap” in the rupture zone created by the two previous major historical earthquakes, which had epicenters near the recent tremor.
The Kamchatka region is under continuous subduction as part of an ongoing tectonic process creating these “seismic gaps.” This is a key aspect in understanding earthquake potential, especially in areas that haven’t ruptured in a long time and may have accumulated geological stress.
The megathrust earthquake is the most powerful type of earthquake occurring in a geological boundary where two plates meet and slide past each other. The term megathrust refers to either the action of the rock above the fault (the overriding plate). When rock is pushed upwards relative to the rock below (the subducting plate) a gap is created which is filled up at a later time. These faults typically dip at a shallow angle called a “subduction zone.”
Tsunami warnings
The Pacific Tsunami Warning Center (PTWC), the Japan Meteorological Agency (JMA), and the US National Weather Service immediately issued warnings and advisories, urging coastal populations to seek higher ground. Initial reports confirmed waves reaching as high as 5 meters (16.4 feet) high striking Russia’s Kuril Islands.
Severo-Kurilsk, the main settlement on the Kuril Islands, was flooded by a long-wave tsunami that partially submerged the fishing port, a fish processing plant, and swept fishing vessels out to sea. In Japan, the highest tsunami waves observed were 1.3 meters (4.25 feet) reported in Kuji Port in Iwate Prefecture. Earlier, 30-centimeter (one-foot) waves were observed in northern Hokkaido.
Phivolcs issued a tsunami alert to coastal areas facing the Pacific Ocean.
Most tsunami warnings globally were canceled 24 hours later.
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