Scientists dig for the guts of earthquakes

CHICAGO -- Scientists are pursuing earthquakes deep into their subterranean lairs, studying them on land and below the sea. Yet, confronted with the question of when and where the "next big one" will occur, an uncomfortable silence sets in.

Based on history there will be quakes in Japan, also in Tibet, said Leigh Royden of the Massachusetts Institute of Technology.

"Will we ever be able to predict them? I don't know," she said Sunday at a meeting of the American Association for the Advancement of Science.

"There have been a few signals associated with quakes, but only in hindsight," she said. "And those quakes are rare."

Quakes most often occur at the boundaries of the many moving plates that make up the surface of the earth. But some also have been recorded well inside the plates, such as the devastating temblor that shook Wenchuan, China last year or the 1811-1812 quakes at New Madrid, Mo., that briefly caused the Mississippi River to flow backward.

Scientists can tell when a plate is under high stress but don't have a way to determine where a fracture will occur, launching a quake, explained Harold Tobin of the University of Wisconsin.

Nevertheless they continue striving to learn more about quakes and their causes in an effort to find ways to protect lives and property.

James Evans of Utah State University said researchers have drilled nearly 11,500 feet into the San Andreas Fault in California to install instruments in hopes of "really getting into the guts of the fault zone" to record an earthquake.

Tobin is taking part in similar research in the Nankai trough in the western Pacific Ocean, one of the most active seismic areas in the world.

"If we want to understand the physics of how the faults really work, we have to go to those faults in the ocean," he said. "Scientific drilling is the main way we know anything at all about the geology of the two-thirds of the Earth that is submerged."

"The ultimate goal is a series of deep holes in the trough in a few years," he said.