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2009 May 18 03:39:36 UTC

Earthquake Details

  • This event has been reviewed by a seismologist.
Location33.937°N, 118.345°W
Depth15.1 km (9.4 miles)
Distances15 km (10 miles) SW of Los Angeles, California
25 km (15 miles) NW of Long Beach, California
30 km (20 miles) SW of Pasadena, California
585 km (365 miles) SSE of SACRAMENTO, California
Location Uncertaintyhorizontal +/- 0.2 km (0.1 miles); depth +/- 0.3 km (0.2 miles)
ParametersNph=189, Dmin=6 km, Rmss=0.44 sec, Gp= 43°,
M-type=centroid moment magnitude (Mw), Version=S
Event IDci10410337
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Earthquake Summary

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Tectonic Summary

A magnitude 4.7 earthquake struck about 3 miles east of Los Angeles International airport at 8:39 p.m. (PDT) local time, at a depth of 8.5 miles. Given that the location is in a densely populated part of the Los Angeles basin, it was widely felt. Initial estimates from the USGS ShakeMap indicate that although strong shaking will have been felt by many people, damage is expected to be light.

The initial focal mechanism is consistent with slip on the Newport-Inglewood fault, which was the source of the damaging 1933 Long Beach earthquake. Three of the early aftershocks, however, are west of the Newport-Inglewood fault trend. Later aftershocks are expected to help define the fault plane that ruptured. The Los Angeles basin is crossed from northwest to southeast by the intensively studied Newport-Inglewood fault zone. In 1920, the Inglewood earthquake (M 4.9) occurred in nearly the identical location to this evening's earthquake. The 1920 event was the original reason for identification of this as an active fault zone capable of damaging earthquakes, which then later proved to be the case in the 1933 Long Beach event. After the 1933 event, the name of the fault zone was changed to the Newport-Inglewood fault zone in recognition that it is continuous from Beverly Hills to Newport Beach.

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