While the likelihood of a full rupture sits at 30-40%, lead author Valerie Sahakian, who is now a postdoctoral fellow at the USGS in Menlo Park, says that a smaller natural disaster in the magnitude 5 or 6 range could still have a significant impact on the region.
San Diego - A recent study of the Institution of Oceanography at the University of California San Diego (UCSD) shows that there is a significant fault between San Diego and Los Angeles that could be the cause of a magnitude 7.4 quake in California.
With this approach, the researchers were able to define the fault architecture in more detail than ever, allowing them to estimate the magnitudes with greater accuracy. The disparate data have different resolution scales and depth of penetration providing a "nested survey" of the region. The researchers identified four faults separated by three stepovers - a term used by geologists to denote points where the faults are offset horizontally. "Large, but less damaging earthquakes, like magnitude 7.5, may be the more typical type of occurrence along this stretch of the fault", Graves said. She is now a postdoctoral fellow with the U.S. Geological Survey. A high 5- or low 6-magnitude quake is already considered a threat. If the southern onshore segment also ruptures, an estimated magnitude 7.4 natural disaster may occur. The last major temblor occurred 160 years ago, a catastrophic geological event that ruptured an astonishing 185 miles of the San Andreas fault.More news: African-Americans seven times more likely to be wrongfully convicted
A repeat of the 1857 quake could damage aqueducts that deliver water into Southern California from the north, disrupt electric transmission lines and tear up Interstate 5, whose Grapevine section runs on top of the San Andreas Fault at Tejon Pass.
Previously, this system produced a 6.4 magnitude quake in Long Beach, Calif that killed 115 people in 1933. It's not the big one. San Diego State University seismologist Tom Rockwell has recently completed research in Old Town that suggests that the fault has been far more active in the past than once believed, raising the prospect that a significant quake could hit one of San Diego's most densely populated areas.
There would be waves of cargo planes, helicopters and ships, as well as tens of thousands of soldiers, emergency officials, mortuary teams, police officers, firefighters, engineers, medical personnel and other specialists. "The San Andreas for the most part - even the 7.8 magnitude prediction - does very little damage".