Mysterious Tremors Found Deep Under San Andreas

View Comments ()
|
Email
|
Print

    NEWSLETTERS

    Getty Images
    Scientists observe mysterious tremors deep in California's mighty San Andreas Fault.

    Scientists have detected a spike in underground rumblings on a section of California's San Andreas Fault that produced a magnitude-7.8 earthquake in 1857.

    What these mysterious vibrations say about future earthquakes is far from certain. But some think the deep tremors suggest underground stress may be building up faster than expected and may indicate an increased risk of a major quake.

    Mystery Surronds New Earthquake Fears

    [BAY] Mystery Surronds New Earthquake Fears
    Strange underground tremors near the San Andreas fault has some scientists concerned. (Published Friday, Jul 10, 2009)

    Researchers at UC Berkeley monitored seismic activity on the fault's central section near Parkfield between July 2001 and February 2009 and recorded more than 2,000 tremors. The tremors lasted mere minutes to nearly half an hour.

    Unlike earthquakes, tremors occur deeper below the surface and the shaking lasts longer.

    Tremor episodes persist today. Though the frequency of tremors have declined since 2004, scientists are still concerned because they are still at a level that is twice as high as before the 2003 quake.