New Earthquake Model for L.A. Finds Some Faults Moving Faster Than Expected

[Dover]

Cooke and Marshall's model suggests that the Verdugo-Eagle rock fault is moving about .8 mm per year and should be further studied and trenched. Credit: University of Massachusetts Amherst


An analysis of slip rates for 26 active faults in the Los Angeles metropolitan area validates a new approach to modeling fault tectonics and finds that some faults may be moving faster than earlier models estimated, University of Massachusetts Amherst scientists report.

The new model incorporates interactions that occur deep in the Earth’s crust, and should offer more accurate data to earthquake probability models, which are used by the state of California to set insurance rates. The work is published in the Nov. 21 issue of Geophysical Research Letters.

To estimate earthquake risk, scientists like to start with direct measurements such as slip rates—the speed with which one side of a fault moves in relation to another. But for many faults—such as the Verdugo fault that runs through Glendale and Burbank in the eastern San Fernando valley—such data aren’t available.

To fill in the gaps where direct measurements are impossible or difficult to obtain, scientists will often use models that simulate geologic deformations. But previous models of the L.A. metropolitan area—a network of interacting active faults in several directions—have oversimplified fault geometry and thus predicted unusually high slip rates, says Michele Cooke, a structural geologist at UMass Amherst.

So Cooke and her doctoral student Scott Marshall set out to devise a model that would preserve the complexity of the L.A. basin fault system topology, but wouldn’t take years of measurements and number-crunching to complete. Using a technique known as the Boundary Element Method, or BEM, they developed a three-dimensional model based on detailed fault surface data compiled in the Community Fault Model of the Southern California Earthquake Center.

In the new model, faults move due to stresses and strains arising from regional deformation, but they also may move due to neighboring fault activity. This is important, says Cooke, because how faults are connected has a lot do with how they will behave...cont'd

http://www.physorg.com/news82747143.html

[rumpel]

1. that's an interesting site

thanks -

problem with earthquakes is - there is nowhere to go

I wonder what the colors signify though

[bananas]

2. Up

Most earthquakes last less than a minute,
if you could go up - for example in a jet pack, or helium balloons - you would be safe.

[xchrom]

3. that's if you didn't get hit by a brick on it's way down.

[bananas]

4. Helmets.

That's what helmets are for.