Mount Shasta earthquake series poses no immediate hazard

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Since February 19, 2015 an ongoing series of small earthquakes has been occurring approximately 5 miles southeast of the summit of Mount Shasta, near the Clear Creek Trailhead on a regional, unnamed fault at about 3-5 miles depth.

Since February 19, 2015 an ongoing series of small earthquakes has been occurring approximately 5 miles southeast of the summit of Mount Shasta, near the Clear Creek Trailhead on a regional, unnamed fault at about 3-5 miles depth. To date, twenty events at or above magnitude M1.0 have been recorded, the largest of which, a M2.1, occurred on April 1. A single M1.1 earthquake was recorded beneath the summit of the volcano on March 17. The current earthquake series poses no immediate hazard, but it is notable given the low overall background seismicity observed at Mount Shasta. The typical number of earthquakes per year tally to about ten events concentrated southeast of the summit between 5 to 10 miles away. 

In addition to the ongoing earthquake series, seismic stations recorded a modest rock avalanche on the south flank of the mountain on March 30, at  18:20 PST. Smaller rock falls shook seismometers in the minutes preceding this event.   The rock slide appears to be unrelated to the ongoing earthquakes series, as no earthquakes preceded the rock slide event.

Plot of earthquakes in Mount Shasta region greater than M1.0 from A...

Plot of earthquakes in Mount Shasta region greater than M1.0 from April 3, 2010 to April 3, 2015.

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