Notable Earthquake of the Week

Coalinga M 6.7 Earthquake  

At 4:42 p.m, PDT May 2, 1983, a strong earthquake measuring M 6.7 struck an isolated region of the western San Joaquin Valley near Coalinga, California. The main shock occurred near Anticline Ridge about 15 km northeast of Coalinga. It was felt from the Los Angeles area north to Susanville and from the Pacific Coast to western Nevada. (Click on the images for a larger picture)

Nearly 200 people were injured and about 1,000 were left homeless - fortunately, no deaths were reported. The temblor caused more than $30 million in damages, forcing the town to rebuild a 12-block section of the downtown and shut down production from nearby oil fields for some time.

Of 139 buildings in the eight-block downtown commercial district, 59 collapsed or were heavily damaged. The most severe damage occurred to the old (usually pre-1930) one- and two-story buildings of unreinforced brick masonry wall construction, with floors and roofs of wood. Newer buildings of reinforced concrete-block walls or prefabricated metal had little structural damage. Underground public utilities (water, electricity, gas, sewerage) sustained little damage considering the above ground damage.

Private residences were heavily damaged. More than eight hundred single-family houses were destroyed or incurred major damage. Most of these domestic buildings were of unreinforced adobe construction.

Strong aftershocks continued for more than 2 years, with the largest event registering M 6.0 on July 22. Although surface faulting did not occur from the main shock, a strong M 5.7 aftershock produced a maximum of 64 cm of reverse and 20 cm of right-lateral displacement along a 3.3 km long trace of the previous unnamed Nunez fault, about 12 km northwest of Coalinga.



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