A major earthquake measuring 6.7 or more is 99 per cent likely to hit California within the next 30 years, scientists said Monday in releasing the first official forecast of statewide earthquake probabilities. ( dpa )
The report by a team of federal and state earthquake scientists said that a much more damaging quake of magnitude of 7.5 or greater is at least 46 per cent likely to hit within the same period.
The 6.7 magnitude Northridge quake of 1994 killed 60 people, left 20,000 homeless and damaged more than 40,000 buildings.
The study "basically guarantees it's going to happen" again by 2037, said Ned Field, a geophysicist with the US Geological Survey in Pasadena and lead author of the report. The quake's precise time and location is not known.
The scientists said that they hoped their findings would jolt awareness about the dangers facing California.
"In our two major metropolitan areas where odds are high that a large quake is coming, people think a lot about quakes whenever even a smaller one shakes, but 10 days later most folks forget them, and they shouldn't," said David Schwartz, an earthquake geologist at the US Geological Survey.
The scientists used new analytical tools and computer programs to arrive at their new forecasts of earthquake magnitudes and the faults they may rupture.
By their calculations, the probability that a 6.7 magnitude quake will hit on any one of the faults in the San Francisco Bay area is now set at 63 per cent, only slightly higher than the 62 per cent estimated in 2003.
The analysis was the first that scientists have done of probabilities for quakes on several Southern California faults. They calculated the odds of a 6.7 magnitude quake striking within 30 years somewhere in the greater Los Angeles at 67 per cent, according to the report.