Latest San Andreas Fault Stories

The magnitude 7.0 earthquake that triggered disastrous destruction and mounting death tolls in Haiti this week occurred in a highly complex tangle of tectonic faults near the intersection of the Caribbean and North American crustal plates, according to a quake expert at the Woods Hole Oceanographic Institution (WHOI) who has studied faults in the region and throughout the world.Jian Lin, a WHOI senior scientist in geology and geophysics, said that even though the quake was "large but not...

Link to earthquakes unclear, but tremors seem to increase stress on shallower fracture zoneThe faint tug of the sun and moon on the San Andreas Fault stimulates tremors deep underground, suggesting that the rock 15 miles below is lubricated with highly pressurized water that allows the rock to slip with little effort, according to a new study by University of California, Berkeley, seismologists."Tremors seem to be extremely sensitive to minute stress changes," said Roland...

Most earthquakes occur along fault lines, which form boundaries between two tectonic plates. As the relative speed of the plates around a fault increases, is there a corresponding increase in the number of earthquakes produced along the fault? According to this study published in the December issue of BSSA, the answer depends upon the type of tectonic boundary. On certain types of boundary, the efficiency of earthquake production actually depends on the fault slip rate.Seismic hazard...

Using a technique normally used for detecting weak tremors, scientists at the Georgia Institute of Technology discovered that the 2004 magnitude 6 earthquake along the Parkfield section of the San Andreas fault exhibited almost 11 times more aftershocks than previously thought.  The research appears online in Nature Geoscience and will appear in print in a forthcoming edition."We found almost 11 times more events in the first three days after the main event. That's surprising because this...

With an average of four mini-earthquakes per day, Southern California's San Jacinto fault constantly adjusts to make it a less likely candidate for a major earthquake than its quiet neighbor to the east, the Southern San Andreas fault, according to an article in the journal Nature Geoscience."Those minor to moderate events along the San Jacinto fault relieve some of the stress built by the constantly moving tectonic plates," said Shimon Wdowinski, research associate professor at the...

Scientists say many recent earthquakes might have been the aftershocks of large quakes that occurred hundreds of years ago, BBC News reported.Researchers have described a new pattern in the frequency of aftershocks that could explain some major quakes.A report published in the journal Nature found that, away from plate boundaries, echoes of past earthquakes could continue for several hundred years, since the earth takes longer to recover in the middle of a continent.Seth Stein from...

U.S. scientists studying the giant 2004 earthquake that caused Indian Ocean tsunamis say they've determined the quake weakened part of the San Andreas Fault. The seismologists said their findings suggest the Earth's largest earthquakes can weaken fault zones worldwide and might trigger periods of increased global seismic activity. An unusually high number of magnitude 8 earthquakes occurred worldwide in 2005 and 2006, said Rice University Associate Professor Fenglin Niu, one of the study's...

Researchers at the Carnegie Institution say that they have discovered a method of measuring and monitoring geological fault lines beneath the Earth's crust"”a development that could significantly enhance scientists' ability to accurately predict earthquakes.Geologists previously had no means with which to detect and measure the fluctuating strength of faults that are hidden beneath the Earth's surface.  Now, however, researchers from the Carnegie Institution's Department of Terrestrial...

New Zealand is the site of one of the world's youngest subduction zones, where the Pacific Plate of Earth's crust dives beneath the Australian Plate. Now, a University of Utah study shows how water deep underground helps the subduction zone mature and paves the way for it to generate powerful earthquakes.The study in the Aug. 6 issue of the journal Nature "expands our understanding of the sources of earthquake failure," says Phil Wannamaker, the study's main author and a...

Tremors deep within the San Andreas Fault suggest California should not become complacent about future earthquakes, a leading seismologist said. The San Andreas fault is changing down deep and it's changing down deep in places where large earthquakes have happened in the past, said Robert Nadeau, a research seismologist at the University of California, Berkeley. Seismic activity in the central part of the fault has increased in the years since the magnitude 6.5 San Simeon quake in 2003 and...