A new theory presented at the annual meeting of the American Geophysical Union is shaking up the seismologist world (they are likely tired of this joke, but will, I'm sure, understand). Live Science reports that USC geologist John Platt and University of Mainz technphysicist Cees Passchier are positing that a number of faults, upon colliding, merge instead of breaking past one another. They're using the term "zipper" to describe the effect.
At a rock formation called Cap de Creus in Spain, Platt and Passchier noticed that existing ideas weren't holding up, as shears of rock on either side of the fault were oriented in opposite directions. "[Passchier] showed it to me in the field; it just blew my mind," Platt told Live Science. "I thought 'There's just no way, it's completely impossible."
Platt was reminded of a spot about 60 miles north of Los Angeles in the mountain town of Gorman. There, the San Andreas Fault collides with the Garlock Fault — but instead of blowing past each other in the classic conception, one fault deactivating the other (we know that not to occur) some kind of merger instead takes place, the scientists believe.
Now the team has modeled 27 different versions or movements of zipper faults, from their "unzipping" to their "zipping" to everything in between. According to Platt, the theory "may solve some long-standing and intractable problems concerning the timing and displacement on faults."
Platt and Passchier hope to pursue GPS testing here in California: At the intersection of the San Andreas and Garlock Faults, the rate at which each slips should, according to their theory, be lesser than the rate, say, south of the intersection. That, they would assume, was due to their zipping/merging in Gorman.
"I really like it," geodynamics researcher Ivanka Mitrovic said after the presentation. It's "very simple, but it's that simple brilliance," she added, saying it "would help connect opposing opinions." You know, zipping it all up, I guess.