In maps, visuals: Collision of Earth plates behind Pacific quake, tsunami

India Today

5 days ago

The massive earthquake that sent sea water as high as 16 feet crashing into Russia's Kuril Islands was the result of a dramatic underground collision between Earth's tectonic plates. India Today explains what caused it — and what it tells us about the restless plates beneath the Pacific.
A convergent boundary occurs when two tectonic plates crash into each other due to compressional forces, while a transform boundary is a result of two plates sliding past each other horizontally, rather than colliding or pulling apart
advertisementWHERE DID IT HAPPEN?A magnitude 8.8 earthquake struck east of Petropavlovsk-Kamchatsky, a coastal city in Russia's Far East, at 11:24 pm Indian time on July 29, 2025. The earthquake area falls in the Kuril-Kamchatka subduction zone where the Pacific Plate dives beneath the North America Plate — a tectonic process responsible for some of the world's most violent quakes and tsunamis. This region sits on a convergent plate boundary where the Pacific Plate has been moving northwest against the North American Plate at about 80 mm/year, as per the US Geological Survey (USGS). The Pacific Plate is considered one of the fastest convergent margins in the world.
The North American plate extends westward beyond the North American continent deep into Russia. 'The earthquake's location and sense of motion are consistent with faulting on the subduction zone plate interface of the Kuril-Kamchatka arc,' the USGS said in a note.
The USGS says that earthquakes of this size are more appropriately described as slips over a larger fault area. It estimates the size of the fault area – the area of the Pacific Plate that went under the North American Plate – to be about 390 km in length and 140 km in width.
ACTIVE SEISMIC ZONEThe Kamchatka earthquake is the largest event to occur globally since the 9-magnitude earthquake which hit Japan in 2011, and among the top ten largest earthquakes to occur globally in over a century.
The largest recorded earthquake in the Kamchatka section of the subduction zone was a 9 magnitude earthquake in 1952, whose epicentre is less than 30 km from the epicentre of the July 29 quake
For the last 10 days, a series of low to medium magnitude earthquakes has occurred offshore the Kamchatka peninsula. More than 50 earthquakes of magnitude 5 and higher have occurred in this period, including a 7.4 magnitude earthquake on July 20. After the 8.8 magnitude quake, more than 24 aftershocks greater than 5 magnitude were recorded in the region.The 1952 earthquake ruptured 600 km of the subduction zone. This region has accommodated about 6 meters of plate motion since then. The latest earthquake appears to have filled any small gap in the ruptures created by earthquakes of 1923 and 1952, the USGS note says.- EndsTune InTrending Reel