12/27/2015, M4.3 near Johannesburg

Last updated October 4th, 2019

  • 27 Dec 2015 10:31:17 PST, (35.215, -117.280), depth 0.7km, 37km ESE of Johannesburg, California
  • Aftershocks: so far (04 Jan 2016) there have been 9 aftershocks recorded, the largest M2.3. More may be expected in the next few days, the largest expected is approximately 1 magnitude unit smaller than the mainshock. There is a small chance (about 5%) that a larger quake could occur, with the likelihood decreasing over time.
  • There were 5 events during the 3 days prior to the earthquake (within a 1 km radius), the largest was M3.8 (2015/12/26). See the earlier post for details.
  • Historical seismicity: since our records began in 1932 we’ve had 3 events of M4 or greater within 10km of today’s event, the largest was M4.7 (1992/06/29) and the most recent was M4.1 on 30 Jun 1992.
  • Nearby faults: Blackwater fault zone (Blackwater fault) (4.7 km), Harper fault zone (Black Mountain fault) (5.1 km), Harper fault zone (Gravel Hills fault) (6.8 km), Harper fault zone (Harper Valley fault) (8.5 km), Blackwater fault zone (9.1 km) and Harper fault zone (Cuddeback fault) (10.9 km).
  • Links for: USGS earthquake page, ShakeMap, DYFI.
  • Visit our special reports page for further information on local notable earthquakes.
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