Structural geologist Michele Cooke calls it the “million-dollar question” that underlies all work in her laboratory at the University of Massachusetts Amherst: what goes on deep in the earth as strike-slip faults form in the crust? This is the fault type that occurs when two tectonic plates slide past one another, generating the waves of energy we sometimes feel as earthquakes.
Structural geologist Michele Cooke calls it the “million-dollar question” that underlies all work in her laboratory at the University of Massachusetts Amherst: what goes on deep in the earth as strike-slip faults form in the crust? This is the fault type that occurs when two tectonic plates slide past one another, generating the waves of energy we sometimes feel as earthquakes.
Geologists have been uncertain about the factors that govern how new faults grow, says Cooke. In recent years she and colleagues have offered the first systematic explorations of such fault evolution. In their new paper, she and her team of students provide experimental results to illustrate the process, with videos, and report on how they re-enact such events in wet clay in the lab. Details appear in the current online edition of Journal of Structural Geology.
Cooke says, “When I give talks to other geologists I put up a picture of a fault and ask, wouldn’t you love to be able to see exactly how that formed? Well, in my lab that’s what we do. We set up the conditions for faulting on a small scale and watch them unfold. People have done this before, but we’ve developed methods so we can see faults grow in very, very fine detail, at a finer resolution than anyone has documented before.”
The UMass Amherst researchers take a mechanical efficiency approach to understanding fault development. It states that faults in the crust reorganize in accord with “work optimization” principles, or what Cooke refers to as the “Lazy Earth” hypothesis. It focuses on fault systems’ effectiveness at transforming input energy into movement along the faults. Like lightning striking the closest object, when forming a fault the earth takes the easiest path.
Read more at University of Massachusetts at Amherst
Image: Geologists have been uncertain about the factors that govern how new faults grow, Cooke says. In recent years she has offered the first systematic explorations of such fault evolution, providing experimental results to illustrate the process, with videos. (Credit: UMass Amherst)
