The United States Geological Survey
recorded a Magnitude 6.5 Earthquake at a depth of 10.0 km about 72 km to
the west of Challis in Custer County, Idaho, slightly after 4.50 pm
local time (slightly after 11.50 pm GMT) on Tuesday 31 March 2020.
There are no reports of any serious damage or injuries associated with
this event, but it was felt across much of western North America, from Vancouver and Calgary in the north to Las Vegas and Los Angeles in the south.
A rockfall on Highway 21 near Lowman, Idaho, following a Magnitude 6.5 Earthquake on 31 March 2020. Tyler Boyer/The Spokesman Review.
The quake took part in an area known as the Central Idaho Seismic Zone,
which is bisected by six active faults, the Madison,
Centennial, Beaverhead, Lemhi, Lost River, and Sawtooth. These faults
are associated with the Yellowstone Magma Chamber in the northeast of
Wyoming, an area that suffers more-or-less constant small tremors due to
the movement of magma beneath the surface, but which seldom experiences
larger quakes. The constant small movements around Yellowstone can lead
to stress building up in rocks further away, leading to Earthquakes as
the rocks release the strain by readjusting their positions, which can
affect Wyoming as well as neighbouring Idaho and Montana. The same
faults also suffer stress due to more distant rock movements, notably on
the subduction zone on the American west coast.
The approximate location of the 31 March 2020 Custer County Earthquake. USGS.
Witness accounts of Earthquakes can help geologists to understand these
events and the underlying structures that cause them. If you felt this
quake (or if you were in the area but did not, which is also useful
information) then you can report it to the United States Geological
Survey here.
See also...
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