Featured Research

from universities, journals, and other organizations

Creeping Reduces Quake Risk On Berkeley Fault, Say Science Authors

Date:
August 24, 2000
Source:
American Association For The Advancement Of Science
Summary:
A new model of the northern Hayward Fault in California's San Francisco Bay Area suggests that a major earthquake along that portion of the fault may be less likely than previously suspected, according to a report in the 18 August issue of the journal Science.

Washington D.C. -- A new model of the northern Hayward Fault in California's San Francisco Bay Area suggests that a major earthquake along that portion of the fault may be less likely than previously suspected, according to a report in the 18 August issue of the journal Science.

The Hayward fault is one of the major branches of the well-known San Andreas Fault System that crisscrosses coastal California. In 1868, a major earthquake of magnitude 7 occurred on the southern portion of the Hayward, rupturing over a distance of 40 to 50 kilometers between the cities of Fremont and Berkeley.

Many scientists have traditionally believed that there is a high probability of a major earthquake on the northern portion of the fault within the next 30 years, potentially endangering lives and property in the area.

But a type of fault motion called aseismic creep, say the Science researchers, may be relieving strain on the northern portion of the fault.

"The likelihood of a large earthquake originating and centering on the northern Hayward fault alone is rather low," says the study's lead author Roland Bürgmann of the University of California, Berkeley.

Fault zone properties like temperature, stress, fluids, and the type of rock help determine whether the adjacent crustal blocks of a fault move past each other in the relatively abrupt, stick-and-slip motion that causes earthquakes, or in a more gradual, smooth motion called aseismic creep. Since at least the turn of the century, the northern Hayward fault has been showing telltale signs along its surface trace--including diverted street curbs, wavering fence lines, and cracked and distorted buildings--of aseismic creep.

These surface creep rates lag behind long-term slip rates for the fault, however, suggesting that the creep only extends for a shallow distance below the surface and that the fault is "locked" at a deeper level below, accumulating strain that would be released in a major earthquake.

To test the extent of aseismic creep on the northern Hayward, Bürgmann and colleagues integrated data from global positioning satellite measurements along the fault with satellite radar data and information from clusters of microearthquakes deep within the fault. The researchers combined these data in a model that correlates surface movements with fault slippage at depth, says Bürgmann, allowing them a 3-D glimpse of the fault zone.

Their analysis revealed a slow and aseismic creep at the bottom as well as the top of the fault zone in the northern part of the Hayward. The seismic scenario that best fits their model, say the Science researchers, is of a Hayward Fault with a split personality: a relatively immobile southern half that is locked at depth, adjacent to a freely-slipping northern segment.

Although the deep creep along the northern Hayward indicates that the possibility of a major earthquake along that portion of the fault should be downgraded, Bürgmann says that these findings do not rule out large earthquakes on neighboring fault segments, like the southern half of the Hayward or the Rodgers Creek fault that lies north of the Hayward fault.

"The studies that have been done clearly suggest significant earthquake hazard from these and other faults in the Bay area," says Bürgmann.

Bürgmann also notes that the lower likelihood of a quake on the northern Hayward has no effect on the collateral damage that might occur in this area from nearby fault events that cause significant shaking.

The other members of the research team are D. Schmidt, R. M. Nadeau, M. d'Alessio, T. V. McEvilly, and M. H. Murray at University of California, Berkeley, E. Fielding at California Institute of Technology, and D. Manaker at University of California, Davis. Funding for this work was supported by grants from the NSF Geophysics program, NASA's Solid Earth and Natural Hazards program, and the U.S. Geological Survey (USGS) NEHRP program.


Story Source:

The above story is based on materials provided by American Association For The Advancement Of Science. Note: Materials may be edited for content and length.


Cite This Page:

American Association For The Advancement Of Science. "Creeping Reduces Quake Risk On Berkeley Fault, Say Science Authors." ScienceDaily. ScienceDaily, 24 August 2000. <www.sciencedaily.com/releases/2000/08/000824082006.htm>.
American Association For The Advancement Of Science. (2000, August 24). Creeping Reduces Quake Risk On Berkeley Fault, Say Science Authors. ScienceDaily. Retrieved October 21, 2014 from www.sciencedaily.com/releases/2000/08/000824082006.htm
American Association For The Advancement Of Science. "Creeping Reduces Quake Risk On Berkeley Fault, Say Science Authors." ScienceDaily. www.sciencedaily.com/releases/2000/08/000824082006.htm (accessed October 21, 2014).

Share This



More Earth & Climate News

Tuesday, October 21, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

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
Hey, Doc! Sewage, Beer and Food Scraps Can Power Chevrolet’s Bi-Fuel Impala

Hey, Doc! Sewage, Beer and Food Scraps Can Power Chevrolet’s Bi-Fuel Impala

3BL Media (Oct. 20, 2014) — Hey, Doc! Sewage, Beer and Food Scraps Can Power Chevrolet’s Bi-fuel Impala Video provided by 3BL
Powered by NewsLook.com
White Rhino's Death In Kenya Means Just 6 Are Left

White Rhino's Death In Kenya Means Just 6 Are Left

Newsy (Oct. 20, 2014) — Suni, a rare northern white rhino at Ol Pejeta Conservancy, died Friday. This, as many media have pointed out, leaves people fearing extinction. 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