EXPERTS ADVISORY

ANN ARBOR—A powerful magnitude-7.0 earthquake struck southern Japan today, roughly a day after a smaller quake hit the same region and killed nine people. University of Michigan experts are available to discuss the quakes.

Eric Hetland is a geophysicist and an associate professor in the Department of Earth and Environmental Sciences. His work is broadly concerned with lithospheric deformation, principally the inference of the mechanical properties of the crust and upper mantle from observations.

Hetland said the quakes this week in Japan occurred along the same fault system. But they are not on the same fault that was responsible for 2011’s magnitude-9.0 earthquake in Japan, he said.

“This week’s shallow earthquakes involved mostly side to side ground motion. In contrast, subduction earthquakes like the 2011 event involve significant vertical ground motion,” Hetland said. “When that occurs under oceans it can lead to tsunamis, as we saw in 2011.”

Hetland can be reached at 734-615-3177, 734-678-6590 or at [email protected].

Jeroen Ritsema is a professor of geophysics in the Department of Earth and Environmental Sciences. His research involves the analysis of seismic waves to image Earth’s interior. He said this week’s Japan earthquakes occurred in a complex seismic setting where the corners of three tectonic plates meet.

“Both events were the result of horizontal sliding that probably occurred along the same fault,” Ritsema said.
Contact: 734-615-6405, [email protected]