© University of Hawaii, ManoaThe top diagram shows the lobes of movement, uplift in red and subsidence in blue, found using GPS data, while the bottom diagram shows the lobes predicted by an earthquake simulation model.
Analysis of GPS data has revealed new areas of motion around the San Andreas Fault System.
Using data collected by the EarthScope Plate Boundary Observatory's GPS array, researchers identified 125-mile-wide "lobes" of uplift and subsidence. Over the last several years, the lobes, which straddle the fault line, have hosted a few millimeters of annual movement.
Computer models simulating the San Andreas Fault System have predicted such crustal movement, but the areas of motion hadn't been physically identified until now. Researchers used advanced statistical modeling to identify the movement among the inevitable statistical noise that comes with monitoring minute movements in the Earth's crust.
"While the San Andreas GPS data has been publicly available for more than a decade, the vertical component of the measurements had largely been ignored in tectonic investigations because of difficulties in interpreting the noisy data," lead author Samuel Howell, a researcher at the University of Hawaii at Manoa,
explained in a news release. "Using this technique, we were able to break down the noisy signals to isolate a simple vertical motion pattern that curiously straddled the San Andreas fault."
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