The Indonesian Meteorological, Climatological, and Geophysical Agency recorded a Magnitude 6.2 Earthquake at a depth of about 10 km, beneath West Sumatra Province, Indonesia slightly before 8.40 am Western Indonesian Time (slightly before 1.40 am GMT) on Friday 25 February 2022. There have been seven reported fatalities following this incident, including two children, with another 85 injured and damage to about 410 buildings. The event was felt across West Sumatra and Riau provinces, as well as much of Peninsula Malaysia and Singapore, with about 6000 people being temporarily evacuated from their homes in Sumatra and Malaysia.
The Indo-Australian Plate, which underlies the Indian Ocean to the west of Sumatra, is being subducted beneath the Sunda Plate, a breakaway part of the Eurasian Plate which underlies Sumatra and neighbouring Java, along the Sunda Trench, passing under Sumatra, where friction between the two plates can cause Earthquakes. As the Indo-Australian Plate sinks further into the Earth it is partially melted and some of the melted material rises through the overlying Sunda Plate as magma, fuelling the volcanoes of Sumatra.
This does not happen at a 90° angle, as occurs in the subduction zones along the western margins of North and South America, but at a steeply oblique angle. This means that as well as the subduction of the Indo-Australian plate beneath the Sunda, the two plates are also moving past one-another. This causes rifting within the plates, as parts of each plate become stuck to the other, and are dragged along in the opposing plate's direction. The most obvious example of this is the Sumatran Fault, which runs the length of Sumatra, with the two halves of the island moving independently of one-another. This fault is the cause of most of the quakes on the island, and most of the island's volcanoes lie on it.
See also...
Follow Sciency Thoughts on Facebook.
Follow Sciency Thoughts on Twitter.
