Monday 2 December 2019

Magnitude 4.5 Earthquake in Curry County, Oregon.

The United States Geological Survey recorded a Magnitude 4.5 Earthquake at a depth of 16.7 km, roughly 6 km to the northeast of the city of Port Oreford in Curry County, Oregon, at about 1.45 am local time (about 9.45 am GMT) on Saturday 30 November 2019. This was not a large quake, and no damage or injuries have been reported, but it was across much of southwest Oregon and in parts of northern California.

The approximate location of the 30 November 2019 Curry County Earthquake. USGS.

Oregon forms the southern part of the Cascadia Subduction Zone, along which the Juan De Fuca plate, which underlies part of the northeast Pacific, is being subducted beneath the western margin of the North American Plate. This is not a smooth process, and the two plates frequently stick together then break apart again as the pressure builds up, causing Earthquakes in the process. The heat and pressure within the Earth also slowly melts the subducting plate, liquefying more volatile minerals which then rise through the overlying North American Plate as magma, fuelling the volcanoes of America's Pacific Northwest.
Subduction along the Cascadia Subduction Zone. Kathleen Cantner/American Geosciences Institute/Earth Magazine.

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 United States Geological Survey here.

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