Biggest California Earthquake of 2012: M6.3 December 14, 2012

Location and tectonic setting of the California earthquake of December 14, 2012. Image credit: USGS

A large earthquake of magnitude 6.3 (M6.3) struck off the Californian coast around 185 miles south west of San Diego in the early hours of Friday, December 14, 2012.

Although the epicentre of the quake was underwater, the quake was not sufficiently large to generate a tsunami and no tsunami alert has been issued.

The tremor, which occurred at a depth of around six miles, was followed by at least one aftershock of M4.3 but at the time of writing no injuries or damage to property had been reported.

California Earthquake: Tectonic Setting

The Pacific coast of North America is notoriously vulnerable to seismic activity.

Much of the area represents the boundary between the Pacific and North American tectonic plates (it is part of the seismically active zone known as the Pacific Ring of Fire) while further south, off the Mexican coast, the situation becomes more complex as the Pacific, Cocos and North American plates are juxtaposed.

The epicenter of California’s 14 December quake was located within the Pacific Plate approximately 300 miles from the plate boundary itself, at a point where the boundary (which varies in nature along its length) changes from a constructive margin at which new ocean crust is formed, to a transform margin, at which crust is neither generated nor lost.

Movement along the transform section, which forms the notorious San Andres Fault Zone, is lateral, or strike-slip. Latest information from the USGS, however, suggests that the earthquake resulted from faulting within the Pacific Plate, rather than movement at the plate boundary.

Click to Read Page Two: Recent Earthquakes in California

© Copyright 2012 Jennifer Young, All rights Reserved. Written For: Decoded Science
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  1. Robert says

    I can’t be the only one not thinking of Dec 21st & what that can mean considering this now, a precursor to the big show? Yikes!

    • Zeracan says

      As someone who follows earthquakes, and thinking the a big one is coming soon. You know what happened after this quake. The whole central cal area opposite of this in Mammoth Lakes and all around there became active consistently. Before this quake that area was comparatively silent. Afterwards that area lit up with 1s, 2s, and just activity in general compared to only a few 2/3s every few weeks just around the various spots. Now, guaranteed quakes in mammoth everyday.

  2. Jim says

    Guessed it

    Sun and moon in very close proximity stradling galactic center this morning – tidal forces at peak.

    I only figured something significant might move. It is just uncanny this alignment was present at this hour.

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