Earthquakes occur along fault lines between continental plates, where one plate is diving beneath another.
Earthquakes occur along fault lines between continental plates, where one plate is diving beneath another. Pressure builds between each plate, called fault stress. When this stress builds enough to release, the plates slip and grind against each other, causing an earthquake.
Researchers have long thought that this force is the central driver of earthquakes. But another force is also in the mix: the properties of the rocks in the fault zones along the plate interface. This includes both the structure of the rock as well as how the rocks are arranged along the zones.
Now, a University of Michigan study looking at a small region in Japan has shown that the properties of fault zone rocks really matter for the generation of earthquakes.
Yihe Huang, lead author and U-M associate professor of earth and environmental sciences, and her team looked at data from the eastern Kanto region of Japan, including Tokyo. The region is situated where the Philippine Sea Plate is sandwiched between the North American Plate and the Pacific Plate.
Read more at University of Michigan
Photo Credit: Schematic figure of the subduction zone underneath the Kanto region (left) in Japan and the spatial distribution of magnitude 2 to 6 earthquakes on the subduction zone at 60 to 70 kilometers below Earth's surface (right). The inset of the left figure demonstrates the foliated shear zone that causes the frequency occurrence of deep interplate earthquakes. (Credit: Yihe Huang, University of Michigan)
