Pacific Northwest tectonic plates move

CORVALLIS, Ore., April 12 (UPI) -- Oregon State University scientists say the three major tectonic plates off the Pacific Northwest coast are undergoing a gradual shift.

The geologists say the area in which the plates converge -- popularly known as the Triple Junction -- appears to be migrating in a southeasterly direction.

The change isn't a cause for alarm, researchers say -- it has been slowly taking place over millions of years. But technological advances and data from formerly classified U.S. Navy hydrophones are giving scientists a new perspective on the underlying geology of the region and might change previous accepted models of seafloor spreading, undersea volcanism and, ultimately, seismic hazards.

The "reorganization" of the Triple Junction may indicate that the subduction of the northern portion of the Juan de Fuca plate beneath the North American plate may be slowing and eventually cease, said Robert Dziak, an Oregon State University associate professor.

"In many ways, it is becoming more like the San Andreas Fault to the south, where the earthquake danger comes from strike-slip events, rather than a subduction quake."

The research appears in the current issue of the journal Geology.