Sunday 15 December 2019

Magnitude 6.9 Earthquake in Davao del Sur Province, the Philippines.

The Philippine Institute of Volcanology and Seismology recorded a Magnitude 6.9 Earthquake at a depth of 3 km about 5 km to the west of the town of Matanao in Davao del Sur Province on Mindanao Island, Philippines, slightly after 2.10 pm local time (slightly after 6.10 am GMT) on Sunday 15 December 2019. The Earthquake is known to have killed at least four people, including a six-year-old girl, and injured many more, mostly in building collapses with the event being felt across the southern Philippines. 

 Vicitms of the 15 December 2019 Davao del Sur Earthquake, trapped beneath a wall in the town of Padada. Korte Supremo/Twitter.

The geology of the central Philippines is Complex. The west of Mindanao Island is located on the Banda (or Sunda) Microplate, and the east on the Philippine Plate, which is being subducted beneath the Sunda (or Banda) Microplate along the central part of the island. Immediately to the east of the Island the Pacific Plate is being subducted along the Philippine Trench, and passes beneath eastern Mindanao as it sinks into the Earth. This is not a smooth process, an the plates constantly stick together then break apart again as the pressure builds up, resulting in Earthquakes.

 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.

The location of the 15 December 2019 Davao del Sur Province Earthquake. Contour lines show rates of movement during the quake, the red line is a boundary between two tectonic plates, in this case the Pacific and Philippine plates. USGS.

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