The United States Geological Survey
recorded a Magnitude 5.9 Earthquake at a depth of 20.3km, beneath the northern part of Posi Posi Rao Island in the North Maluku Province of Indonesia, slightly slightly after 1.05 am local time on Sunday 19 November 2017
(slightly after 4.05 pm on Saturday 18 November, GMT). There are no reports of any casualties associated with this event, but it did cause some minor damage to buildings in Posiposi village, on the south part of the island.
Damage to buildings on Posiposi Rao Island following the 19 Novenmber 2017 Earthquake. Earthquake Report.
Posiposi Rao lies at the northern end of the Halmahera Islands chain, a volcanic arc formed where one tectonic plate is
being subducted beneath another, with the underlying plate being melted
by the heat of the Earth's interior, and lighter minerals bubbling up
through the overlying plate to form volcanoes. However the Halmahera
Islands are unusual in that they lie on a double subduction zone. The
underlying plate, a northeaster extension of the Molucca Sea Plate, is
being overridden form the Philippine Plate from the east and the
Eurasian Plate from the west. The Halmahera volcanoes are located where
the Philippine Plate is overriding the Molucca Sea Plate; to the west
the Sangihe Islands lie where the Molucca Sea Plate is being overridden
by the Eurasian Plate.
Diagrammatic representation of the subduction zones beneath Halmahera
(middle), plus the Philippines (top) and Sulawesi (bottom), with the
Eurasian Plate to the left, the Molucca Sea Plate in the middle, and the
Philippine Plate to the right. Hall & Wilson (2000).
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 approximate location of the 19 November 2017 Posiposi Rao Earthquake. USGS.
See also...
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