Significant Earthquakes and Faults
Chronological Earthquake Index
Type of Faulting: left-lateral strike-slip, with very minor reverse motion
Time: December 3, 1988 / 3:38 am PST
Location: 34° 8.47' N, 118° 7.96' W Directly below the city of Pasadena.
Fault Involved: Raymond fault
Depth: 15.6 km
Apart from its effects on local residents, this quake was notable for a few seismological details. First, it was followed by an unusually small number of aftershocks for a quake of its magnitude, the largest of which was hardly noticable -- only a magnitude 2.4 (unless the Montebello earthquake is considered an aftershock of this event). Second, it served to bring the debate over the sense of motion of the Raymond fault closer to an end, by providing a clear example of left-lateral movement most likely located along that fault.