San Andreas Fault on EARTH Magazine

Where will the San Andreas Fault rupture next?

Mon, 10 Sep 2018 09:52:10 -0400

In this satellite image of the Salton Sea region of Southern California, the San Andreas Fault Zone can be seen to the east of the sea. This is where researchers say the structure of the fault may be ideal for hosting a very large earthquake. Credit: Jacques Descloitres, MODIS Rapid Response Team, NASA/GSFC.

In 1906, the San Andreas Fault Zone ruptured, and the shaking that followed brought the city of San Francisco to its knees. Buildings toppled and fires raged and, in the end, more than 3,000 people died as a result. Since then, Californians have often wondered aloud when and where the next “Big One” will strike. Geologists do not know the answers, but recent research has offered a new clue: Field mapping of the San Andreas’ southernmost reaches, near the Salton Sea, reveals a type of fault structure that researchers think may be just right for triggering a big earthquake.

San Andreas Fault shook Bay Area three times in a century

Mon, 23 Jun 2014 15:52:53 -0400

Ashley Streig and her colleagues examined tree stumps among other proxies. Tree-ring dating indicates this tree was cut prior to the earthquake of 1838 on the San Andreas Fault in the Santa Cruz Mountains. Credit: University of Oregon.

“This project took a lot of footwork,” says Ashley Streig, a paleoseismologist at the University of Oregon and lead author of the new study, published in the Bulletin of the Seismological Society of America. Using historical records, including written accounts of earthquake damage to Spanish-built missions in the area, Streig and colleagues identified and mapped the active fault trace through the Santa Cruz Mountains using both field reconnaissance and airborne Lidar.

Californians prepare for the Big One

Thu, 05 Jan 2012 06:41:58 -0500

At 10 a.m. local time Thursday, a massive magnitude-7.8 earthquake struck Los Angeles. But don’t worry — it was only a drill.

During the Great Southern California ShakeOut Drill, more than 10 million people, ranging from businessmen to schoolchildren, will be exposed to extreme shaking. More than 5 million people will “drop, cover and hold on.” Meanwhile, fire and rescue, together with 300 scientists and engineers, will work to save the city. At least 600,000 buildings will have some damage — much of it from the fires that will rage after the shaking stops — and there will be at least $200 billion in damage. Electricity will be out in some areas for days, and water could be out for as long as six months. And about 1,800 people will be “killed” and 50,000 “injured.”

Creeping faults warn of impending earthquakes?

Thu, 05 Jan 2012 06:41:58 -0500

San Andreas Fault U.S. Geological Survey (USGS): photographer Robert E. Wallace, USGS.

Researchers drilled the San Andreas Fault and extracted core samples that are now being studied. John I. Garver, National Science Foundation

Studying the San Andreas Fault, Fenglin Niu and colleagues recently found a way to help determine that an earthquake is coming. Fenglin Niu

Earthquakes strike out of nowhere — one minute everything is perfectly calm, and the next minute, the ground shakes violently and buildings crumple. However, many seemingly sudden seismic events are actually preceded by a multitude of creeping changes underground. Detecting and interpreting these changes would help forecast earthquakes, but that detection has proven difficult, partly because scientists don’t yet fully understand the complex chain of events that precipitates a quake. Now a team of researchers may have discovered some hidden clues that may help them identify impending quakes.