Monday, February 13, 2012

Magnitude 5.6 Earthquake in Northern California

There was a magnitude 5.6 earthquake in Northern California at 1:07 PM, at a depth of 20 miles. It took place in a lightly populated area, but I assume it was felt in Eureka and other north coast towns. It occurred on land between Eureka and Crescent City, roughly between Redwood Creek and the Klamath River, very close to the Hoopa Reservation.
As can be seen in the map above, earthquakes are not unusual in this area. It lies north of the triple junction where three tectonic plates come together (the Gorda, Pacific and North American). A subduction zone is forcing the Gorda Plate beneath the North American continent, and earthquakes are to be expected. There have been a series of magnitude 7 quakes in the region over the years, including the Petrolia earthquake of 1992. Ultimately the descending plate starts to melt, producing the magmas responsible for California volcanoes like Lassen Peak and Mt. Shasta.
As can be seen from the seismicity map of California above, there have been plenty of earthquakes within the last week, but there is nothing happening that is out of the ordinary. California averages several hundred earthquakes a week, although most are not felt.

Get the official details at this site: http://earthquake.usgs.gov/earthquakes/recenteqsus/Quakes/nc71734741.php#details
Keep track of all the quakes in California here:
http://earthquake.usgs.gov/earthquakes/recenteqscanv/
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