Acela of the ocean

University of Delaware geologist Jessica Warren has contributed to research that brings us one step closer to better understanding how earthquakes operate.

Situated along a stretch of the equator in the Pacific Ocean, between Indonesia and Central America, the Gofar transform fault is one of the fastest moving faults on Earth - cruising along the seafloor at about 140 millimeters per year. This is over four times faster than the San Andreas fault is moving in California.

"Geologically speaking, it's like looking at a moving Acela train next to a SEPTA train on the tracks," said Warren, professor of earth sciences at UD.

Researchers know that the Gofar transform fault line has experienced a magnitude 6 earthquake about every five to six years over the last three decades. It's been studied extensively, as these earthquakes occur at the same places along the fault and at the same intensity, time after time.

What's been unknown, until now, is why parts of this fault experience many small microshocks leading up to a main earthquake rupture, then shut down, while other parts of the fault are quiet before the big event and then experience many aftershocks.

Now, a multi-institutional team of researchers, including UD's Warren, reports that sections of the fault without large magnitude earthquakes actually act like brakes in a fast-moving car, controlling the occurrence of big earthquake events on transform faults. This finding is in contrast with currently accepted models of earthquake behavior.