Scientists explore underwater active seismic fault

The international team of scientists just finished exploring the seabed of the Pacific Ocean, offshore Alaska and British Columbia, in an effort to understand better the Queen Charlotte-Fairweather fault system.

The 1126 km long Queen Charlotte-Fairweather fault marks the boundary of the North American and Pacific Plates and has generated several major earthquakes during the past century. A joint team of scientists from the U.S. Geological Survey, the Natural Resources Canada, the University of Calgary and the Sitka Sound Science Center in Alaska spent 20 days at sea aboard the Canadian Coast Guard Ship, "John P. Tully", looking for clues on the fault's future performance.

The team's investigation operations involved seismic-reflection surveys that use sound to reveal rock layers beneath the seafloor, piston cores that bring up the top several meters of ocean sediment for further scrutiny and cameras with powerful lights dragged just above the seabed.

"We've discovered some incredible features," said Jamie Conrad, a USGS geologist, "such as methane seeps and chemosynthetic communities, large submarine landslides, offset seabed morphology from fault motion, and volcanic edifices."

"This investigation and cruise has revealed a spectacularly active fault zone that probably represents the best-defined and most extensive transform plate boundary found anywhere on Earth," added Gary Greene, from the Sitka Sound Science Center.

"We can think of this fault system as the San Andreas of the north," said Danny Brothers, a USGS research geophysicist. "It appears to be the fastest moving continent-ocean strike-slip fault in the world." Such fast moving faults can trigger earthquakes and tsunamis more frequently than slower faults.

As future events from this highly active seismogenic source threaten the coasts of the United States and Canada, data analysis from the recent expedition will provide a better insight on the anticipated earthquake and tsunami risk for the development of new, large-scale coastal infrastructure in British Columbia and Alaska.