Science News
from research organizations

Sometimes It Takes An Earthquake To Know Where The Fault Lies

Date:
October 27, 1999
Source:
American Institute of Physics
Summary:
Sometimes geologists aren't able to tell a fault is active until there's an earthquake. The recent 7.1 earthquake at the newly named Lavic Lake fault is a good example. Scientists say that faults are sometimes thought to be inactive simply because there is not enough evidence to determine otherwise.
Share:
         
Total shares:  
FULL STORY

CALIFORNIA (October 26, 1999) – The recent 7.1 earthquake at the newly named Lavic Lake fault in Southern California is a good reminder that even geologists aren't always sure which faults are active until there is an earthquake. Lucy Jones, a scientist with the United States Geological Survey Western Earthquake Hazards Team, says many faults in Southern California are labeled "inactive", sometimes simply because there is not enough evidence to determine otherwise.

The problem facing scientists in studying faults like Lavic Lake, is that not all faults are equal when it comes to looking for evidence of activity. Some faults are very defined (you can see the San Andreas from the air), while signs of activity from others are subtle, and can be nearly invisible.

To study the recent activity of a fault, geologist look at something called "offset features". These are rocks (or other geologic material) which can be dated and are separated by some distance, indicating that the fault has moved at some time in the past. Jones says the Lavic Lake fault was labeled inactive because "the one geologist who mapped it did not find an obvious offset feature."

A fault's recent activity is important, says Jones, because it helps researchers identify which faults are likely to move again in the relatively near future. "We work from a paradigm that this decade's earthquakes will be near those in the historic record, or those that show very recent motion." However, Jones points out that the example of Lavic Lake shows that just because a fault line doesn't show recent activity, doesn't mean it's sleeping for eternity.

###

Contacts:

Linda Curtis
Western Earthquake Hazards Team
U.S. Geological Survey
(626) 583-7817

Ruth Ludwin, Research Scientist
Pacific Northwest Seismograph Network
University of Washington
(206) 543-4292
ruth@milli.geophys.washington.edu


Story Source:

The above story is based on materials provided by American Institute of Physics. Note: Materials may be edited for content and length.


Cite This Page:

American Institute of Physics. "Sometimes It Takes An Earthquake To Know Where The Fault Lies." ScienceDaily. ScienceDaily, 27 October 1999. <www.sciencedaily.com/releases/1999/10/991026101522.htm>.
American Institute of Physics. (1999, October 27). Sometimes It Takes An Earthquake To Know Where The Fault Lies. ScienceDaily. Retrieved April 26, 2015 from www.sciencedaily.com/releases/1999/10/991026101522.htm
American Institute of Physics. "Sometimes It Takes An Earthquake To Know Where The Fault Lies." ScienceDaily. www.sciencedaily.com/releases/1999/10/991026101522.htm (accessed April 26, 2015).

Share This Page:


Earth & Climate News
April 26, 2015

Latest Headlines
updated 12:56 pm ET