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Earthquakes in Central California, 1980-1984 |
There have been many earthquake occurrences in central California. This set
of slides shows earthquake damage from the following events: Livermore, 1980, Coalinga,
1983; and Morgan Hill, 1984. All of these earthquakes had a magnitude of 5.9 or higher
with estimates of eight million dollars of damage or more.The Livermore Earthquake
of January 24, 1980. Epicenter: 37.83 N, 121.79 W; depth: 8 km; magnitude: 5.9; damage:
$11.5 million; one death. At 11 A.M. PST on January 24, 1980, an earthquake occurred
that was felt over an area of approximately 75,000 km2 of central California. The
epicenter was 20 km north of Livermore in the vicinity of the Greenville fault. Most
of the damage was of a non-structural type. The most commonly reported damage consisted
of broken gas and water lines, broken windows and glassware, chimney damage, overturned
furniture, mobile homes knocked off supports, cracked plaster, and fallen ceiling
tile. Most of the damage, (about $10 million) occurred in the Lawrence Livermore Laboratory
nuclear research center. Expensive laser equipment was knocked out of alignment or
thrown off supports. Many of the tanks partially or totally failed at the Wente Brothers
Winery on Tesla Road, 4 km southeast of Livermore, causing the loss of more than 90,000
liters of wine. The overpass at Interstate 580 and Greenville Road had to be repaired
because the paving settled nearly 30 cm during the quake. One death (possibly from
a heart attack) and 44 injuries resulted from this earthquake. Most of the injuries
were due to flying glass, overturned furniture, and falling ceiling tile and lightfixtures.
The Coalinga Earthquake of May 2, 1983. Epicenter: 36.23 N, 120.29 W; depth: 10 km;
magnitude: 6.7; damage: $31 million; no deaths. The earthquake struck the town of
Coalinga, California, (population 7,000) at 4:42 P.M. PDT on May 2, 1983, and was
followed by a large aftershock 3.5 minutes later. 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, an area of about 205,000
km2. The most serious damage occurred in the eight-block downtown commercial district
extending from Third to Seventh Street between Durian and Forest Streets. Of 139 buildings
in this area, 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. In contrast to the severe damage
to old brick buildings, the newer buildings of reinforced, concrete block walls orprefabricated
metal had little structural damage. Most of the public buildings-including the firehouse,
post office, city hall, police station, hospital, and schools-suffered only minor
damage. Public utilities (water, electricity, gas) performed well despite damage to
some units. Private residences were heavily damaged. More than eight hundred single-family
houses were destroyed or damaged. The majority of the 94 injuries occurred in residential
sections of the city.The Morgan Hill Earthquake of April 24, 1984. Epicenter: 37.32
N 121.70 W; depth: 8 km; magnitude: 6.2; damage: $8 million; no deaths. On April 24,
1984 at 1:15 P.M. PST, an earthquake occurred on the Calaveras fault to the east of
San Jose, California. This earthquake was felt over an area of approximately 120,000
km2 in California and western Nevada. The area of moderate damage extended southward
from the epicenter rather than centering on the epicenter. This pattern indicates
that the Morgan Hill earthquake may have been a double event with the second event
being located about 17 km southeast of the main shock. Most of the damage occurred
in Santa Clara County. More than 550 structures hadminor damage. Major structural
damage was generally confined to a very small area on two streets of the Jackson Oaks
subdivision located east of Morgan Hill (population 19,000). Five houses were condemned;
two of these had fallen off their concrete foundations and suffered partial collapse.
Several masonry buildings on Main Street in Morgan Hill were damaged andlater condemned.
Mobile homes fell off supports, causing considerable damage to the furnishings inside.
There were many reports of firesresulting from the quake. Minor damage also occurred
at San Martin and Coyote. Twenty-seven people were injured in this earthquake.
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