Brawley Fault Zone
The Brawley fault zone is a set of faults connected to the Imperial fault zone. it is a complex set, which includes right-lateral strike-slip, thrust and left-lateral and normal fault slips along it’s 15km length. It is an area prone to earthquake swarms, like that which occurred in 1975, which broke the surface for over 10.4 km According to the Southern California Earthquake Data Center the Brawley Fault zone probably ruptures in a magnitude 6 event every 30-40 years.
The most recent significant surface ruptures along the Brawley Fault Zone occurred January to March, 1975, with several quakes under magnitude 5 and October 15, 1979, Magnitude 6.4.