California overdue 'the big one', say scientists . By . Lee Moran . Last updated at 10:23 AM on 1st July 2011 . Quiet of late: The San Andreas Fault is overdue a substantial earthquake . A huge earthquake could soon hit the U.S. West Coast - which has been spared the natural disaster in recent years because of flood control measures. Scientists have claimed the San Andreas Fault, which runs 810 miles through California, is long overdue a quake of at least magnitude 7.0 - the same size that devastated Haiti in 2010. And they said human efforts to control flooding in the area could be the reason for the recent lull in tremors. Major earthquakes in the southern portion of the fault normally happen every 180 years - but worryingly one has not occurred for 300 years. The group analysed images of sediment layers deposited at Salton Sea, currently the largest lake in California, which was once home to the giant pre-historic freshwater Lake Cahuilla. The way the sediment is laid down meant they could identify when flooding or earthquakes took place. In its day, Cahuilla would have dwarfed the Salton Sea by filling the Coachella, Imperial and Mexicali valleys of southeastern California and northeastern Baja California. It is also where the southern San Andreas Fault ends. U.S. Geological Survey marine geologist Daniel Brothers said: 'We have gone back through time and built one of the longest and most robust earthquake records available.' The group's findings suggested that episodic flooding of the lake by the Colorado River during the past 1,200 years triggered earthquakes on underlying small faults. Same again: Scientists believe an earthquake, bigger than the magnitude 6.9 that hit San Francisco in 1989, is due to come soon from the San Andreas Fault . These, in turn, could have impacted the nearby San Andreas Fault, apparently causing it to rupture with large earthquakes. Past studies had suggested that flooding could trigger seismic activity through the rapid filling of lakes. Analysed: Scientists looked at images of sediment layers deposited at Salton Sea . Tremors: Research suggested episodic flooding of the pre-historic Lake Cahuilla by the Colorado River triggered earthquakes . Brothers added: 'But as far as I know, nobody has presented convincing evidence of this relationship using geologic records. 'We didn't set out to study the relationship between flooding and earthquakes. 'The idea presented itself while we were interpreting our data and we realised we couldn't separate the timing of flooding and fault rupture.' Brothers added in the journal Nature Geoscience that, in the past century, human control of the Colorado River may have contributed to the dearth in earthquakes currently seen in the southern San Andreas. This has led to concerns that energy could be building up in the fault without floods to help release the stress. He added: 'We don't know if the next earthquake on the San Andreas Fault will be bigger because of the prolonged quiescent period. 'We have to wait and see if we've actually reset the recurrence interval and if the earthquakes are actually larger.' Lake Bonneville in Utah, Mono Lake in California, the Dead Sea in the Middle East, the Rift Valley lakes of East Africa and Lake Baikal in Russia are similar areas scientists that may now analyse. Future: Scientists may now analyse the Dead Sea in the Middle East .
California overdue 'the big one', say scientists .
California overdue 'the big one', say scientists . By . Lee Moran . Last updated at 10:23 AM on 1st July 2011 . Quiet of late: The San Andreas Fault is overdue a substantial earthquake . A huge earthquake could soon hit the U.S. West Coast - which has been spared the natural disaster in recent years because of flood control measures. Scientists have claimed the San Andreas Fault, which runs 810 miles through California, is long overdue a quake of at least magnitude 7.0 - the same size that devastated Haiti in 2010. And they said human efforts to control flooding in the area could be the reason for the recent lull in tremors. Major earthquakes in the southern portion of the fault normally happen every 180 years - but worryingly one has not occurred for 300 years. The group analysed images of sediment layers deposited at Salton Sea, currently the largest lake in California, which was once home to the giant pre-historic freshwater Lake Cahuilla. The way the sediment is laid down meant they could identify when flooding or earthquakes took place. In its day, Cahuilla would have dwarfed the Salton Sea by filling the Coachella, Imperial and Mexicali valleys of southeastern California and northeastern Baja California. It is also where the southern San Andreas Fault ends. U.S. Geological Survey marine geologist Daniel Brothers said: 'We have gone back through time and built one of the longest and most robust earthquake records available.' The group's findings suggested that episodic flooding of the lake by the Colorado River during the past 1,200 years triggered earthquakes on underlying small faults. Same again: Scientists believe an earthquake, bigger than the magnitude 6.9 that hit San Francisco in 1989, is due to come soon from the San Andreas Fault . These, in turn, could have impacted the nearby San Andreas Fault, apparently causing it to rupture with large earthquakes. Past studies had suggested that flooding could trigger seismic activity through the rapid filling of lakes. Analysed: Scientists looked at images of sediment layers deposited at Salton Sea . Tremors: Research suggested episodic flooding of the pre-historic Lake Cahuilla by the Colorado River triggered earthquakes . Brothers added: 'But as far as I know, nobody has presented convincing evidence of this relationship using geologic records. 'We didn't set out to study the relationship between flooding and earthquakes. 'The idea presented itself while we were interpreting our data and we realised we couldn't separate the timing of flooding and fault rupture.' Brothers added in the journal Nature Geoscience that, in the past century, human control of the Colorado River may have contributed to the dearth in earthquakes currently seen in the southern San Andreas. This has led to concerns that energy could be building up in the fault without floods to help release the stress. He added: 'We don't know if the next earthquake on the San Andreas Fault will be bigger because of the prolonged quiescent period. 'We have to wait and see if we've actually reset the recurrence interval and if the earthquakes are actually larger.' Lake Bonneville in Utah, Mono Lake in California, the Dead Sea in the Middle East, the Rift Valley lakes of East Africa and Lake Baikal in Russia are similar areas scientists that may now analyse. Future: Scientists may now analyse the Dead Sea in the Middle East .
California overdue 'the big one', say scientists .