New studies presented of Hayward fault

December 11, 2007 12:00:00 AM PST
The U.S. Geological Survey says that the Hayward fault is regarded as one of the most hazardous faults in Northern California. It's presenting new studies today about the fault's dangers to the scientists meeting in San Francisco at the American Geophysical Union. The U.S.G.S. says we need to prepare for a massive quake, especially for the East Bay communities which have grown up on the fault. The last major quake on the fault registered a 7 magnitude in 1868.

There are 15,000 geophysicists from around the world gathered for the annual American Geophysical Union Conference. One of the hottest session-topics deals with the imminent danger of the Hayward fault - a location that many seismologists call a tectonic time-bomb. During today's discussion, seismologists will talk about new findings and new tools they've been using to research this danger-zone.

Currently, 2.5 million people live along the Hayward fault. It's expected about 7 million people in the region would feel an earthquake of the same magnitude - that happened back in 1868.

Historical pictures show some of the devastating damage done by that estimated magnitude-7 1868 quake. Concerned scientists say statistics show the Hayward fault has ruptured about every 140-years for its previous five large earthquakes - the next 140-year cycle hits next fall.

During the AGU Conference, U.S.G.S. seismologists are showed a variety maps demonstrating their research, ranging from liquefaction scenarios along the faultline; to geological investigations showing that the Hayward and Calaveras faults are linked at a depth of several kilometers below the surface. Also being revealed for the first time today will be what's called a "lidar" survey of the Hayward fault. These are pictures taken from an airplane at 1,500 feet elevation.

"We also have just acquired new high-resolution, elevation data along the Hayward fault. That can help us map the various strands of the Hayward fault. Once we find those new strands of the fault, we can go in and do geological investigations and get a better idea of the timing of the earthquakes," said Tom Brocher, USGS Seismologist.

The topographical lidar pictures will help show details never before seen and help map out more accurate traces of the faultline. One of the big things that public and private sectors are doing as well as the USGS is pushing a public awareness campaign - because next fall comes that 140 year cycle. The new information that the Calaveras and Hayward faults are connected - that should also ring a bell of worry because we had a 5.6 earthquake just the day before Halloween - right in that region of connection.