Monday 23 October 2017

Magnitude 5.4 Earthquake in Batangas Province, the Philippines.

The United States Geological Survey recorded a Magnitude 5.4 Earthquake at a depth of 198 km beneath Batangas Province on southwestern Luzon Island, the Philippines, slightly after 10.20 pm local time (slightly after 2.20 pm GMT) on Sunday 22 October 2017. There are no reports of any damage or injuries associated with this event, though it was felt across much of the southwestern part of Luzon. This is typical for such large deep earthquakes; releases of energy that would be deadly close to the surface have spread over a wide area before reaching ground level, so that they are felt over a wide area but not particularly dangerous.

The approximate location of the 22 October 2017 Luzon Earthquake. USGS.

The geology of the Philippines is complex, with the majority of the islands located on the east of the Sunda Plate. To the east of this lies the Philippine Sea plate, which is being subducted beneath the Sunda Plate (a breakaway part of the Eurasian Plate); further east, in the Mariana Islands, the Pacific Plate is being subducted beneath the Philippine Sea Plate. This is not a smooth process, and the rocks of the tectonic plates frequently stick together before eventually being broken apart by the rising pressure, leading to Earthquakes in the process.

Subduction beneath the Philippines. Yves Descatoire/Singapore Earth Observatory.

Witness accounts of Earthquakes can help geologists to understand these events, and the structures that cause them. The international non-profit organisation Earthquake Report is interested in hearing from people who may have felt this event; if you felt this quake then you can report it to Earthquake Report here.

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