Įarly developments at the Caltech lab included an earthquake observation network using their own custom-built short-period seismometers, the Richter magnitude scale, and the Modified Mercalli intensity scale (an updated version of the Mercalli intensity scale). The outlook improved when Professor Andrew Lawson brought the state's first monitoring program online at the University of California, Berkeley in 1910 with seismologist Harry Wood, who was later instrumental in getting the Caltech Seismological Laboratory in Pasadena operational in the 1920s. The United States Weather Bureau did record when they happened and several United States Geological Survey scientists had briefly disengaged from their regular duties of mapping mineral resources to write reports on the New Madrid and Charleston events, but no trained geologists were working on the problem until after 1906 when the Coast and Geodetic Survey was made responsible. Prior to that, no agency was specifically focused on researching earthquake activity. Īccording to seismologist Charles Richter, the 1906 San Francisco earthquake moved the United States Government into acknowledging the problem. Following destructive earthquakes in the late 19th and early 20th centuries, real estate developers, press, and boosters minimized and downplayed the risk of earthquakes out of fear that the ongoing economic boom would be negatively affected. By this time, scientists were well aware of the threat, but seismology was still in its infancy. While the 1812 San Juan Capistrano, 1857 Fort Tejon, and 1872 Owens Valley shocks were in mostly unpopulated areas and only moderately destructive, the 1868 Hayward event affected the thriving financial hub of the San Francisco Bay Area, with damage from Santa Rosa in the north to Santa Cruz in the south. Since the three damaging earthquakes that occurred in the American Midwest and the East Coast ( 1755 Cape Ann, 1811–12 New Madrid, 1886 Charleston) were well known, it became apparent to settlers that the earthquake hazard was different in California. From 1850–2004, there was about one potentially damaging event per year on average, though many of these did not cause serious consequences or loss of life. After the missions were secularized in 1834, records were sparse until the California Gold Rush in the 1840s. As Spanish missions were constructed beginning in the late 18th century, earthquakes records were kept. Ship captains and other explorers also documented earthquakes. state of California was documented in 1769 by the Spanish explorers and Catholic missionaries of the Portolá expedition as they traveled northward from San Diego along the Santa Ana River near the present site of Los Angeles. The earliest known earthquake in the U.S.
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