1952 Kern County earthquake

1952 Kern County earthquake

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UTC time	1952-07-21 11:52:16
ISC event	893168
USGS-ANSS	ComCat
Local date	July 21, 1952 (1952-07-21)
Local time	4:52 am PDT
Duration	7.5 seconds (at Taft)[1]
Magnitude	Mw 7.3[2] Ms 7.5[3]
Depth	16 km (9.9 mi)[4]
Epicenter	34°52′N 119°06′W / 34.86°N 119.10°W / 34.86; -119.10[3]
Fault	White Wolf Fault
Type	Oblique-slip
Areas affected	Southern California United States
Total damage	$70 million[5][6]
Max. intensity	MMI XI (Extreme)[4]
Peak acceleration	~ 1.0 g (est)[7]
Casualties	14 killed[5][6] Hundreds injured[5]

The 1952 Kern County earthquake occurred on July 21 in the southern San Joaquin Valley and measured 7.3 on the moment magnitude scale. The main shock occurred at 4:52 am Pacific Daylight Time (11:52 UTC), killed 12 people, injured hundreds more and caused an estimated $60 million in property damage. A small sector of damage near Bealville corresponded to a maximum Mercalli intensity of XI (Extreme), though this intensity rating was not representative of the majority of damage. The earthquake occurred on the White Wolf Fault near the community of Wheeler Ridge and was the strongest to occur in California since the 1906 San Francisco earthquake.

The town of Tehachapi suffered the greatest damage and loss of life from the earthquake, though other locations in Kern County experienced significant damage as well, but its effects were widely felt throughout central and southern California. The July mainshock had a significant aftershock sequence that persisted into July and August with many magnitude 5+ events with intensities of V (Moderate) to VII (Very strong). Six of these aftershocks occurred on the day of the mainshock, but the strongest aftershock came on August 22 as a M5.8 event that had a maximum perceived intensity of VIII (Severe) and resulted in the deaths of two people and caused an additional $10 million in property damage.

Following the event, a field survey was conducted along the fault zone with the goal of estimating the peak ground acceleration of the shock based on visually evaluating precarious rock formations and other indicators. Ground disturbances that were created by the earthquakes were also surveyed, both in the valley and in the foothills, with both vertical and horizontal displacements present in the epicentral area. The strong motion records that were acquired from the event were significant, and a reconnaissance report was recognized for its coverage of the event, and how it set a standard for those types of engineering or scientific papers. Repercussions of the sequence of earthquakes were still being felt in the heavily damaged downtown area of Bakersfield well into the 1990s as city leaders attempted to improve safety of the surviving unreinforced masonry buildings.