Earth regions 'primed' for earthquakes

• Tweet

SAN FRANCISCO, Dec. 4 (UPI) -- Geologic features and activity in the Himalayas and the Pacific Northwest suggest those regions could be primed for major earthquakes, researchers say.

Geophysicists from Stanford University are presenting findings from studies of the regions at a meeting of the American Geophysical Union in San Francisco this week, a university release reported.

The Himalayan range was formed and remains active due to the collision of the Indian and Asian continental plates, creating a fault knows as the Main Himalayan Thrust where 20 seismometers have been gathering data for two years.

Stanford geophysics doctoral student Warren Caldwell noted the MHT has historically been responsible for a magnitude 8 to 9 earthquake every several hundred years.

"What we're observing doesn't bear on where we are in the earthquake cycle, but it has implications in predicting earthquake magnitude," Caldwell said.

Recent detections of magma and water around the MHT indicate which segments of the thrust will rupture during an earthquake, said Caldwell's adviser, geophysics Professor Simon Klemperer.

"The findings are important for creating risk assessments and disaster plans for the heavily populated cities in the region," he said.

Studies were also presented at the AGU meeting focusing on the Pacific Northwest's Cascadia subduction zone, which stretches from northern California to Vancouver Island but has not experienced a major seismic event since it ruptured in 1700.

Stanford postdoctoral scholar Annemarie Baltay said measurements of small seismic tremors in the region can be utilized to determine how ground motion from larger events might behave.

"We can't predict when an earthquake will occur, but we can try to be very prepared for them," Baltay said. "Looking at these episodic tremor events can help us constrain what the ground motion might be like in a certain place during an earthquake."

The 1700 earthquake, estimated at between 8.7-9.2 magnitude, shook the region and created a tsunami that reached Japan.