Featured Research

from universities, journals, and other organizations

Loma Prieta Fault In California Stronger Than Previously Thought

Date:
December 26, 2007
Source:
University of California - Davis
Summary:
A new study adds to evidence that the fault responsible for the 1989 Loma Prieta earthquake in the San Francisco Bay Area, California, is not as unusually weak as had been thought. In general, a "weak" fault is one that ruptures relatively easily, resulting in smaller but more frequent earthquakes, while a "strong" fault can accumulate more strain before breaking in larger shocks.

Faults and plate motions in the San Francisco Bay Region. Yellow lines show the locations of the 1868 M6.8 earthquake on the southern portion of the Hayward Fault and the 1989 M6.9 Loma Prieta earthquake near the San Andreas fault northeast of Monterey Bay.
Credit: USGS

A new study adds to evidence that the fault responsible for the 1989 Loma Prieta earthquake in the San Francisco Bay Area, California, is not as unusually weak as had been thought.

In general, a "weak" fault is one that ruptures relatively easily, resulting in smaller but more frequent earthquakes, while a "strong" fault can accumulate more strain before breaking in larger shocks, said Robert Twiss, professor emeritus of geology at UC Davis and co-author of the study with Jeffrey Unruh of William Lettis and Associates of Walnut Creek, Calif.

The Loma Prieta fault has been described as unusually weak based on studies of the aftershocks from the 1989 earthquake. By looking at the direction and movement of the aftershocks, researchers could calculate the strains in the fault. Previous studies looked at the aftershocks in total.

Twiss and Unruh took a new approach, breaking the aftershocks up into 17 separate clusters. They found that the fault is complex, with different kinds of deformation in different places. When they looked at the aftershocks in greater detail, they found more stresses in the structure.

"You're losing most of the essential mechanical information about the fault by piling these details together," Twiss said.

The researchers also found that the stresses and slip directions of the main earthquake were reproduced in the aftershocks, implying that the stresses continue to be present.

Twiss said that there is "no way" to predict the strength or timing of future earthquakes on the same fault using these results. But the findings would be relevant for other researchers seeking to build models of earthquake faults in the Bay Area, he said.

The paper was published in the September/October 2007 issue of the Geological Society of America Bulletin.


Story Source:

The above story is based on materials provided by University of California - Davis. Note: Materials may be edited for content and length.


Cite This Page:

University of California - Davis. "Loma Prieta Fault In California Stronger Than Previously Thought." ScienceDaily. ScienceDaily, 26 December 2007. <www.sciencedaily.com/releases/2007/12/071219130301.htm>.
University of California - Davis. (2007, December 26). Loma Prieta Fault In California Stronger Than Previously Thought. ScienceDaily. Retrieved October 22, 2014 from www.sciencedaily.com/releases/2007/12/071219130301.htm
University of California - Davis. "Loma Prieta Fault In California Stronger Than Previously Thought." ScienceDaily. www.sciencedaily.com/releases/2007/12/071219130301.htm (accessed October 22, 2014).

Share This



More Earth & Climate News

Wednesday, October 22, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

San Diego Zoo's White Rhinos Provide Hope for the Critically Endangered Species

San Diego Zoo's White Rhinos Provide Hope for the Critically Endangered Species

Reuters - Light News Video Online (Oct. 22, 2014) — The pair of rare white northern rhinos bring hope for their species as only six remain in the world. Elly Park reports. Video provided by Reuters
Powered by NewsLook.com
Trick-or-Treating Banned Because of Polar Bears

Trick-or-Treating Banned Because of Polar Bears

Buzz60 (Oct. 21, 2014) — Mother Nature is pulling a trick on the kids of Arviat, Canada. As Mara Montalbano (@maramontalbano) tells us, the effects of global warming caused the town to ban trick-or-treating this Halloween. Video provided by Buzz60
Powered by NewsLook.com
Traditional Farming Methods Gaining Ground in Mali

Traditional Farming Methods Gaining Ground in Mali

AFP (Oct. 20, 2014) — He is leading a one man agricultural revolution in Mali - Oumar Diatabe uses traditional farming methods to get the most out of his land and is teaching others across the country how to do the same. Duration: 01:44 Video provided by AFP
Powered by NewsLook.com
How Detroit's Money Woes Led To U.N.-Condemned Water Cutoffs

How Detroit's Money Woes Led To U.N.-Condemned Water Cutoffs

Newsy (Oct. 20, 2014) — The United Nations says water is a human right, but should it be free? Detroit has cut off water to residents who can't pay, and the U.N. isn't happy. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:

Strange & Offbeat Stories

 

Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins