More recently, some scientists have suggested the filling of the Zipingpu reservoir in China could plausibly have helped advance the timing of the devastating magnitude 7.9 earthquake in Sichuan in 2008, which killed more than 69,000 people. The reservoir behind the dam began to fill in 1962 five years later, a magnitude 6.2 earthquake struck, resulting in damage to the dam and a nearby town, and 200 people were killed. One documented example, cited in a study published in 1988, involved the Koyna dam in western India. A report published in 1997 noted that seismicity “is likely to be more widespread and deeper for a larger reservoir than for a smaller one.” Scientists have also noticed other examples in which the filling of reservoirs brought earthquake faults closer to failure, possibly advancing temblors, the study said. County’s proposed earthquake rules would require certain older concrete buildings in unincorporated areas, and those owned by the county, to be retrofitted. County moves to require quake retrofits as Turkey-Syria death toll exceeds 50,000 And we still need to be prepared for it.”Ĭalifornia L.A. “Even if the Salton Sea dries up completely, that next southern San Andreas earthquake is still going to happen. They just happened a little bit sooner than they otherwise would have, due to the influence of the filling and emptying of the lakes over time,” Philibosian said. “Even if this ancient Lake Cahuilla or the Salton Sea never existed, these earthquakes would still eventually have happened anyway. Geological Survey who wasn’t affiliated with the study. “The idea that letting the Salton Sea dry up will keep us safe from earthquakes is definitely the wrong takeaway,” said Belle Philibosian, a research geologist with the U.S. The decline of the Salton Sea, however, does not mean Southern California will forever be protected against a San Andreas earthquake as long as that area is desiccating. But its periodic refilling may have been the tipping point that triggered earthquakes when they did occur. Such a quake would’ve inevitably happened whether Lake Cahuilla was there or not. The central reason why earthquakes occur remains the same: Strain has accumulated for decades or centuries because of tectonic plate movement, and the fault suddenly ruptures. “Such a correlation between the earthquake and lake timings is probably not coincidental.” “Although previous studies were inconclusive about the temporal correlation of the earthquakes and lake episodes over the past millennium, the new earthquake history strongly suggests that all lake-filling events were accompanied by large earthquakes,” the study said. Once considered politically impossible because of cost, requiring owners to retrofit their buildings gets overwhelming support from L.A. Of the seven major quakes researchers found, six occurred when Lake Cahuilla either was filling up or was at a peak level.Ĭalifornia When it comes to earthquakes, Republicans and Democrats agree on L.A. “By looking at the earthquake history, and its relationship to the lakes, we realize that most of the earthquakes have occurred when a lake was present,” Rockwell said. Lake Cahuilla is believed to have been full six times in the last millennium: roughly the periods of 930 to 966, 1007 to 1070, 1192 to 1241, 1486 to 1503, 1618 to 1636, and 1731 to 1733. Researchers found a pattern of Colorado River waters pouring into Lake Cahuilla and accompanying large earthquakes before the lake periodically dried up. By contrast, the Salton Sea currently reaches a height of about 240 feet below sea level, and with a maximum depth of about 50 feet. Lake Cahuilla was so vast that it stretched from the Coachella Valley south into Mexico and from as far west as Plaster City, Calif., to as far east as the Chocolate Mountains, according to study co-author Thomas Rockwell, a professor of geology at San Diego State.Ī full Lake Cahuilla reached an elevation of about 40 feet above sea level, with a maximum depth of more than 300 feet before it started to spill again. The ancient predecessor to the Salton Sea is now referred to as Lake Cahuilla, which, when full, was 40 times larger in volume than its modern-day remnant. Officials have identified 33 buildings owned by Los Angeles County as having a flaw that could cause them to collapse in a major earthquake. California These 33 important buildings owned by L.A.
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