See also: Los Angeles Basin, Mendocino Fracture Zone, and Salton Troughĭuring the last 66 million years, nearly the entire west coast of North America was dominated by a subduction zone, with the Farallon Plate subducting beneath the North American Plate. Higher standards were established for fire stations, hospitals, and schools and construction of dwellings was also restricted near active faults. In both cases, the perception of those involved with policy making in California was changed, and state laws and building codes were modified (but not without much debate) to require commercial and residential properties to be built to withstand earthquakes. Some decades later, the San Fernando earthquake affected the San Fernando Valley north of Los Angeles with heavy damage to several hospitals. In 1933, the Long Beach earthquake occurred in a populated area and damaged or destroyed many public school buildings in Long Beach and Los Angeles. Įarly developments at the Caltech lab in Pasadena included an earthquake observation network using their own custom built short period seismometers, the Richter magnitude scale, and 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 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 the Coast and Geodetic Survey was made responsible after 1906. 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. Reactions following destructive events in the late 19th and early 20th centuries included real estate developers, press, and boosters minimizing and downplaying the risk 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 Lone Pine shocks were only moderately destructive in mostly unpopulated areas, the 1868 Hayward event affected the thriving financial hub that is the San Francisco Bay Area, with damage from Santa Rosa in the north to Santa Cruz in the south. The few damaging earthquakes that occurred in the American Midwest and the East Coast were well known ( 1755 Cape Ann, 1811–12 New Madrid, 1886 Charleston), and it became apparent to settlers that the earthquake hazard situation was much different in the West. For the period 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. The earliest known earthquake 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. Other sources for the occurrence of earthquakes usually came from ship captains and other explorers. Those records ceased when the missions were secularized in 1834, and from that point until the California Gold Rush in the 1840s, records were sparse. Although the written history of California is not long, records of earthquakes exist that affected the Spanish missions that were constructed beginning in the late 18th century.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |