12/31/2016, Swarm near Brawley (largest M3.9)

Last updated October 4th, 2019

  • A seismic swarm commenced on December 31st, 2016, near Brawley. So far there have been more than 250 events recorded.
  • The largest event in the swarm so far was a M3.9 on 31 Dec 2016 at 15:06:56 PST, (32.975, -115.545), depth 14.5km, 2km WSW of Brawley, California
  • 8 events over M3 have been recorded and more than 80 events over M2. More than 250 events over M0.5 have been recorded.
  • Cumulative number of events over time (top) and event magnitudes over time (bottom) for the swarm near Brawley.

    Map showing events in the swarm near Brawley coloured by time (blue early, red late) and sized by magnitude. The star marks the largest (M3.9) event in the cluster. Faults are shown as grey lines. Historical seismicity above M4.5 is marked by grey stars and magnitude values.

  • Historical seismicity: since our records began in 1932 we’ve had 22 events of M4 or greater within 10km of today’s event, the largest was M5.8 (1979/10/16) and the most recent was M4.2 on 28 Aug 2012.
  • Nearby faults: Imperial fault (3.9 km), Brawley seismic zone (Brawley fault zone) (6.7 km), San Jacinto fault zone, Superstition Hills section (Superstition Hills flt) (13.6 km) and San Jacinto fault zone, Superstition Hills section (Wienert fault) (14.3 km).
  • Links for: USGS earthquake page, ShakeMap, DYFI.
  • Visit our special reports page for further information on local notable earthquakes.
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