Wednesday 12 June 2019

Magnitude 4.5 Earthquake to the north of Pagan Island, Northern Mariana Islands.

The United States Geological Survey recorded a Magnitude 4.5 Earthquake at a depth of 180.9 km about 19 km off the northwest coast of the Pagan Island, a US possession in the Northern Mariana Islands, slightly after 7.20 pm local time (slightly after 9.20 am GMT) on Thursday 6 June 2019. There are no reports of any casualties this event, though it may have been felt on the island.

The approximate location of the 6 June 2019 Pagan Island Earthquake. USGS.

The volcanic Mariana Islands are located on the eastern margin of the Philippine Plate, close to its margin with the Pacific Plate. The Pacific Plate is being subducted beneath the Philippine Plate along the Mariana Trench. This is not a smooth process, an the plates constantly stick together then break apart again as the pressure builds up, resulting in Earthquakes.

 Simplified diagram of the subduction of the Pacific Plate beneath the Philippine plate, and how this fuels the volcanoes of the Mariana Islands. NOAA Ocean Explorer.

Witness accounts of quakes can help geologists to understand these events and the rock structures that cause them. If you felt this quake (or if you were in the area but did not, which is also useful information) you can report it to the USGS here.

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