BEIJING, April 15 (Xinhuanet) -- California is 99 percent certain of being struck by a strong earthquake sometime in the next 30 years, scientists said as quoted by media reports Tuesday.

    New calculations reveal there is a 99.7 percent chance a magnitude 6.7 quake or larger will strike in the next 30 years, according to a study conducted by the U.S. Geological Survey, the Southern California Earthquake Center and California Geological Survey Monday. The study used new data and analyzing earthquake probabilities across the state.

    The chances of a monster quake, measuring 7.5 or greater, were predicted at 46 percent over the same projected period, with densely populated southern California most likely to be affected.

    "It basically guarantees it's going to happen," said Ned Field, a geophysicist with the U.S. Geological Survey in Pasadena and lead author of the report.

    The group also found that two of California's largest cities -- Los Angeles and San Francisco -- were more than 63 percent likely to face a 6.7 quake.

    The Jan. 17, 1994, Northridge quake in Los Angeles killed 72 people, injured more than 10,000 and caused billions of dollars in damage.

    Knowing the likelihood of a strong earthquake is the first step in allowing scientists to draw up hazard maps that show the potential severity of ground shaking in an area. The information can also help with updating building codes and emergency plans and setting earthquake insurance rates.

    (Agencies)