While the San Andreas fault gets most of the headlines for its seismic activity on the west coast of America, researchers claim that it is the Hayward Fault which is long overdue and could destroy the San Francisco area if a mega quake strikes.
Water, electricity and gas supplies could be affected, and hillside areas are seen shaking more than flat land in the most detailed simulation ever made of a magnitude 7 earthquake.
Most of the 2.5 million people now living in the San Francisco Bay area would be affected, the study warns.
The Hayward Fault is a 74-mile fault line on the west coast of the USA running parallel with the San Andreas Fault, to the east of central San Francisco.
Simulations from a supercomputer at the Lawrence Livermore (LLNL) and Lawrence Berkeley (LBNL) national laboratory show there is a one in three chance that there will be a 6.7 or higher magnitude quake in the San Francisco Bay area in the next 30 years.
Artie Rodgers, LLNL seismologist and lead author of the paper, said: “This study shows that powerful supercomputing can be used to calculate earthquake shaking on a large, regional scale with more realism than we’ve ever been able to produce before.”
Using data from previous earthquakes, the simulation is the most detailed ever made of a magnitude 7 quake in the area.
The simulation shows the quake would shake for 20 seconds, and of course, the greatest damage is in the areas closest to where the fault is – where nearly 2.5 million people live.
In a separate study from the US Geological Survey (USGS), seismologists called the Hayward Fault a “tectonic time bomb”.
The report from the USGS warns that Hayward Fault “is among the most active and dangerous in the United States.”
It states that a 7 magnitude quake could cause 800 deaths and more than 18,000 injuries.
USGS earthquake geologist emeritus David Schwartz told the LA Times: “The fault is what we sort of call a tectonic time bomb
“It’s just waiting to go off.”