The last big quake to strike the southern part of the San Andreas fault occurred in 1857. The nightmare scenario that plays out in the minds of countless seismologists and geological experts in the region centers around the San Andreas Fault, the longest faultline in California that runs directly through some of the state’s most densely populated regions.
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The last time San Andreas acted up in 1857, it resulted in a 7.9-magnitude quake tearing 185 miles through the state from Monterey County to the San Gabriel Mountains. “And the southern San Andreas fault, in particular, looks like it’s locked, loaded and ready to go”.
The fault hasn’t moved much southeast of the Cajon Pass since an natural disaster in 1812 while the area of the dried up Salton Sea has been quiet since the 1680s.
Thomas Jordan gives the opening keynote address, saying the San Andreas fault is “locked, loaded, and ready to roll”.
But Jordan says that California needs to continue its preparation efforts to prepare for when the San Andreas fault finally releases all of the stress that it’s been collecting.
Based on the movement of the Pacific and North American plates, seismologists say it should be relieving about five metres of stress a century – but that hasn’t been happening.
Jordan said Californians should brace for an quake as strong as magnitude 8.
It’s not only the southern San Andreas that is a cause for concern, said Jordan. “The pressure has been building on that part of the fault without being relieved for more than a hundred years”, he said. “We know politically how hard it is to make these kinds of changes”. The report also estimated such a catastrophe could leave areas without a sewer system for up to six months.
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Los Angeles Fire Dept. firefighter paramedics practice caring for mock natural disaster victims during the Great Southern California ShakeOut, a simulation of a mass casualty quake. In anticipation of an 8.0 magnitude natural disaster, officials in Los Angeles enhanced the aqueduct and telecommunications system in the city and reinforced aging concrete buildings.
