Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Scientists offer new model for forecasting the likelihood of an earthquake

12.12.2006
In assessing the probability of an earthquake, scientists rely on two important pieces of data that are often inconsistent. The past geological record sometimes tells one story, while current measurements from the Global Positioning System (GPS) tell another. But a new forecasting model designed by Stanford University geophysicists may help close the gap.

"This is the most realistic model to date," said Kaj Johnson, assistant professor of geological sciences at Indiana University, who worked on the modeling project several years ago when he was a Stanford graduate student. "This is something people had been asking for years now. It's the next step."

Johnson and Stanford geophysics Professor Paul Segall will present their new probability model at 11:35 a.m. PT on Dec. 14, at the annual meeting of the American Geophysical Union in San Francisco during a talk titled "Distribution of Slip on San Francisco Bay Area Faults" in Room 307, Moscone Center South.

Measuring faults

An important component of earthquake-probability assessment is determining how fast a fault moves. One technique involves the use of GPS, which allows seismologists to measure the movement of various points on the surface of the Earth, then use these data to extrapolate underground fault movement. Another way to determine fault slip rates is to dig a trench across the fault and find the signatures of past earthquakes, a method called paleoseismology.

"People say, let's compare rates of fault movement from GPS to rates of fault movement from geologic studies," Segall said. "But it's as if you're measuring different parts of the same thing with different tools. The discrepancy can be quite big."

To bridge the gap, Segall and Johnson created a new model that weaves together everything known about how a fault moves. The idea for the model came when Segall was asked to speak at a conference on the "rate debate," which is how geophysicists refer to the GPS-paleoseismology discrepancy. That's when he realized that the standard model doesn't take into account that fault-slippage rates vary over time.

This time dependence is important, because GPS doesn't measure fault slippage directly. Rather, it measures how quickly points on the surface of the Earth are moving. Then scientists try to fit these data into mathematical models to estimate the rate of slip. "Because of the time-dependent rate, your estimate depends on where you are in the earthquake cycle," Segall said. "So if you use a model that doesn't take that into account, you will get a slip rate that's different."

The scientists hope that their new updated model can give a more accurate picture of slip rates and reconcile the two pieces of fault data.

California and Asia

With the new model, the team confirmed that the slip rates from GPS and from the geological record for the San Francisco Bay Area are relatively consistent. "Along the San Andreas system, the numbers tend to come out in reasonable agreement," Segall said.

The next step for the scientists is to use their time-dependent model to scrutinize faults in other tectonically active regions, such as China, where there is a large disparity between contemporary GPS data and the paleoseismological record. "We want to take the same philosophy and procedure and apply it to different places in the world where the discrepancy can be quite big," Segall noted. "We're developing a strategy for how to move forward. We're still very much in the progress phase."

Johnson is working on applying the new model to faults in Taiwan and Tibet, where the earthquake hazard is great. "This can help inform people who make the forecasts," Johnson said. "These new time-dependent models are going to become the norm, I think."

Mark Shwartz | EurekAlert!
Further information:
http://www.stanford.edu

More articles from Earth Sciences:

nachricht Sea ice extent sinks to record lows at both poles
23.03.2017 | NASA/Goddard Space Flight Center

nachricht Less radiation in inner Van Allen belt than previously believed
21.03.2017 | DOE/Los Alamos National Laboratory

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

Im Focus: Researchers Imitate Molecular Crowding in Cells

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

When Air is in Short Supply - Shedding light on plant stress reactions when oxygen runs short

23.03.2017 | Life Sciences

Researchers use light to remotely control curvature of plastics

23.03.2017 | Power and Electrical Engineering

Sea ice extent sinks to record lows at both poles

23.03.2017 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>