The earthquake that rocked the Seattle-Tacoma region recently may have triggered underwater landslides in Puget Sound that could undermine port facilities built on river deltas. Based on sightings of what appeared to be plumes of disturbed sediment after the earthquake, the U.S. Geological Survey has asked the National Oceanic and Atmospheric Administration ship Rainier to do emergency hydrographic surveys of the Puyallup (Tacoma), Nisqually (Olympia) and Duwamish (Seattle) river delta fronts, the U.S. Commerce Department's NOAA said today.

"We're glad we can respond quickly to USGS's request. Rainier is in Puget Sound already to do surveys of Port Townsend and Admiralty Inlet so those nautical charts can be updated," said Capt. Sam DeBow, NOAA Corps, who is chief of NOAA's Hydrographic Surveys Division, National Ocean Service, in Silver Spring, Md. "Rainier has all the capabilities needed to help USGS determine if the port facilities are at risk. Although there is more concern about finding damage to land-based facilities than finding hazards to navigation, we'll also see from the survey data if any shoaling has occurred because of the earthquake. Whatever we find, NOAA will update the nautical charts of those areas accordingly."

Rainier is scheduled to survey the Puyallup delta in Commencement Bay on March 19, the Nisqually delta in Nisqually Reach on March 20, and the Duwamish delta in Elliot Bay on March 30. The ship will depart Puget Sound on April 2 for Alaska.

USGS will use Rainier's survey data to create new topographic maps of the river deltas for comparison with pre-earthquake maps to evaluate whether submarine landslides have created a potential unseen hazard to any of the area port facilities. In addition, determining the presence or absence of landslides will provide an important advance in understanding the triggering forces of submarine landslides in delta sediment.

These special surveys must be completed quickly because the strong tidal currents in Puget Sound may alter the evidence of small landslides in a matter of weeks. Mapping these deltas provides a unique opportunity to add significant scientific observations that would otherwise not be made.

Rainier is one of three hydrographic survey ships–the only one on the West Coast–in the NOAA fleet that conducts hydrographic surveys in support of the nautical charting mission of NOAA's ocean service. Equipped with global positioning system side-scan sonar, multi-beam survey technology, echo sounders, data acquisition and processing computers, and six survey launches, the ship is one of the most modern and productive survey platforms of its type in the world.

Rainier is home ported in Seattle, Wash. Most of its survey work is conducted in Alaskan waters, where many areas have never been charted.

As part of the NOAA fleet of research ships and aircraft, Rainier is operated and managed by the Office of Marine and Aviation Operations, composed of civilians and commissioned NOAA Corps officers. The NOAA Corps is a uniformed service of the United States, whose officers–all scientists or engineers–provide NOAA with an important blend of operational, management, and technical skills that support the agency's programs at sea, in the air, and ashore. Rainier is under the command of Cmdr. Daniel Herlihy, NOAA Corps.

NOTE TO EDITORS: Media are invited to go aboard Rainier and its survey launches to see the ship's state-of-the-art technology and observe the emergency survey work underway on the following dates: March 20 (Tacoma) and March 30 (Seattle). Please plan on spending about two and a half hours. Contact Jeanne Kouhestani at (301) 713-3431, Ext. 220 (in Maryland), or by pager at (877) 929-8360 to make arrangements.