#AceHistory2Research – CALIFORNIA – March 29 – The first strong earthquake listed in earthquake annals for California occurred in the Los Angeles region in 1769, probably near the San Andreas Fault.
Four violent shocks were recorded by the Gaspar de Portola Expedition, in camp about 30 miles south-east of Los Angeles centre.
Most authorities speculate, even though the record is very incomplete, that this was a major earthquake.
Forty persons attending church at San Juan Capistrano on December 8, 1812, were killed by a strong earthquake that destroyed the church. Many mission buildings were severely damaged there and at San Gabriel. The shock probably centred on a submarine fault offshore.
A violent shock near Fort Tejon in January 1857 threw down buildings and large trees at the Fort. It was also severe in Los Angeles, San Francisco, and Sacramento. This earthquake has been compared to that of April 1906; both caused extensive displacement along the San Andreas Fault. One source notes, “The magnitude of the two events cannot have differed greatly.”
A strong earthquake occurred on the Hayward Fault, the principal active branch of the San Andreas in central California, in October 1868. Some 30 persons were killed in the region. Damage was severe at San Francisco; many buildings were wrecked at Hayward and San Leandro. Until 1906, this shock was often referred to as “the great earthquake.”
An earthquake in the Sierra – Nevada Fault system in March 1872, killed 27 people at Lone Pine and destroyed 52 of 59 adobe houses. Near Owens Lake, numerous depressions formed between cracks in the earth. One area 200 to 300 feet wide sank 20 to 30 feet; several long, narrow ponds formed. Thousands of aftershocks, some severe, appear to have occurred.
Nearly all brick structures were wrecked, and many frame buildings were damaged in Vacaville by an earthquake on April 19, 1892. Damage was similar at Winters and Dixon, two small towns nearby. Ground fissures were noted in the area. The shock centred north of Santa Rosa, in the Healdsburg Fault area.
On Christmas Day of 1899, six persons died and several were injured at Saboba, near San Jacinto, by a strong shock. At nearby Hemet, nearly all brick buildings were severely damaged, with only two chimneys remaining upright. This shock occurred on the San Jacinto Fault, and has been compared to the April 1918 (magnitude 6.8) shock in the same region.
Seven hundred persons died on April 18, 1906, in one of the greatest earthquakes ever to hit California. Damage was extensive in San Francisco, and was increased perhaps tenfold by raging fires. Total damage was estimated at over $500 million.
Research Material Courtesy of: http://earthquake.usgs.gov/