January 17, 2021 Mount Hood Earthquake Swarm

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An earthquake swarm at Mount Hood is ongoing. The earthquakes are associated with regional faulting and are not a sign of changes in volcanic activity.

Since noon local time on January 17, there have been over 100 individual earthquakes in an area south of the summit of Mount Hood. At the time of this statement, the PNSN has located several 10's of these earthquakes with a maximum magnitude of M2.7 and depths mostly around 5 km (3 mi) below sea level. Swarms at Mount Hood are common and account for most of the seismicity at the volcano; they can last hours to days. The location of the earthquakes is similar to other swarms in this area that occurred in 2009, 2012, 2014 and 2020.

Mount Hood earthquakes since 2010 map and cross section

Top: Map View of earthquakes at Mount Hood since 2010 (black circles) and the current swarm (red circles), both sized by magnitude. Blue triangles are current seismic stations. Dark lines are highways around the volcano. Bottom: Cross section from line between A and A' above. Dark line is outline of volcano. Earthquakes marked as above.

(Credit: Weston Thelen. Public domain.)

Earthquakes at Mount Hood, plot

Top: Event rate per week of earthquakes around Mount Hood since 2010. Each spike represents a swarm of earthquakes at the volcano. The current swarm is at the right margin of the plot. Bottom: Depth of earthquakes plotted in time since 2010. The time axis is the same as the top plot.

(Credit: Weston Thelen. Public domain.)

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Date published: July 9, 2019

Earthquake swarm at Mount Hood July 8-9, 2019

Earthquakes occurring on tectonic faults and are not directly related to volcanic processes occurring beneath Mount Hood

Date published: October 11, 2017

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Date published: May 16, 2016

Recent Mount Hood earthquake swarm typical for this Oregon volcano.

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Date published: April 9, 2012

April 8, 2012, earthquake swarm ~20 km south of Mount Hood

The swarm is consistent with a tectonic, rather than magmatic, origin.

Date published: March 9, 2012

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Starting at approximately 22:00 pm PST on March 7, 2012, a small swarm of earthquakes has been occurring near Mount Hood.

Date published: February 24, 2012

Earthquakes at Mount Hood, February 2012.

Typically, several earthquake swarms occur each year at Mount Hood, with some lasting for hours, others lasting for days to weeks.