Saturday, February 27, 2010

Tsunami Details

Here at OEM we are monitoring the tsunami. For Oregon it is predicted to be negligible (around half a meter or about 1.5 - 2 feet), but local sea floor and terrain in some areas might make the wave a little larger. Tsunami wave heights peak about 2 hours after they arrive. So we recommend that you stay away from the beach until after the event.

The estimated times of arrival for Oregon are found at http://wcatwc.arh.noaa.gov/2010/02/27/725245/09/webeta725245-09.txt

Cape Blanco, Oregon 1350 PST FEB 27
the Oregon-California border 1350 PST FEB 27
Charleston, Oregon 1402 PST FEB 27
Cascade Head, Oregon 1426 PST FEB 27
Newport, Oregon 1429 PST FEB 27
Tillamook Bay, Oregon 1434 PST FEB 27
the Oregon-Washington border 1439 PST FEB 27
Seaside, Oregon 1446 PST FEB 27
La Push, Washington 1456 PST FEB 27
Westport, Washington 1457 PST FEB 27
Point Grenville, Washington 1459 PST FEB 27
the Washington-British Columbia border 1501 PST FEB 27
Neah Bay, Washington 1507 PST FEB 27
Astoria, Oregon 1511 PST FEB 27


This graphic shows the predicated path of the tsunami and the predicted wave heights. The areas in the red are estimated to be up to 100 cm in height, although the angle, local sea floor, and coastal terrain can affect how high the wave crests on the shore.

It is located at http://wcatwc.arh.noaa.gov/chile/chileem.jpg.

Tsunami Watch for Oregon

Some interesting information on the Chilean earthquake from George Priest and Antonio Baptista:

“The relatively large depth of the EQ (21 miles) and its location on the coast rather than significantly off the coast of Chile has limited the seafloor uplift and resulting tsunami, so only ~2 m of tsunami struck in the near field. The poor geometry of the wave propagation toward Oregon will limit the height to some small percentage of this value when it arrives ~ 2 PM.

The problem for emergency managers is how to respond to the NOAA advisory warning people off of waterfront/beaches. In Newport we have the seafood and wine festival all weekend, so large numbers of people are right at the waterfront. While it is unlikely that they will be in significant danger, given the way Yaquina Bay dissipates tsunami energy (our previous simulations), prudent emergency managers may well want to move folks away from the waterfront. The main lines of people waiting to get into the big tent is a flat parking lot near the Rogue brewery. Other parts of the coast will have similar difficult decisions.”


I just sent this info out via the FlashAlert Network state-wide:

For more information, contact:
James Roddey, Earth Sciences Information Officer, Oregon Dept. of Geology and Mineral Industries (971) 673-1543 (direct line) / (503) 807-8343 (cell)

This is the latest information (9:58 AM) from the West Coast and Alaska Tsunami Warning Center:

A TSUNAMI ADVISORY IS IN EFFECT WHICH INCLUDES THE COASTAL AREAS OF CALIFORNIA - OREGON - WASHINGTON - BRITISH COLUMBIA AND ALASKA FROM THE CALIFORNIA-MEXICO BORDER TO ATTU ALASKA...

Wave heights in Oregon, at this point, are not expected to be much more that a foot at most and it looks like they will arrive at about low tide on our coast, early this afternoon. Wave heights at Port Orford, OR are estimated to be 0.3M/1.0 FT, with wave heights expected to peak approximately two hours after initial arrival.

This From NWS/WCATWC:

RECOMMENDED ACTIONS:
A TSUNAMI HAS BEEN GENERATED WHICH COULD IMPACT THE ADVISORY REGIONS LISTED IN THE HEADLINE. PERSONS IN LOW-LYING COASTAL AREAS SHOULD BE ALERT TO INSTRUCTIONS FROM THEIR LOCAL EMERGENCY OFFICIALS. EVACUATIONS ARE ONLY ORDERED BY EMERGENCY RESPONSE AGENCIES - PERSONS IN TSUNAMI ADVISORY AREAS SHOULD MOVE OUT OF THE WATER, OFF THE BEACH AND OUT OF HARBORS AND MARINAS.

A TSUNAMI ADVISORY MEANS THAT A TSUNAMI CAPABLE OF PRODUCING STRONG CURRENTS OR WAVES DANGEROUS TO PERSONS IN OR VERY NEAR THE WATER IS IMMINENT OR EXPECTED. SIGNIFICANT WIDESPREAD INUNDATION IS NOT EXPECTED FOR AREAS UNDER AN ADVISORY. CURRENTS MAY BE HAZARDOUS TO SWIMMERS... BOATS... AND COASTAL STRUCTURES AND MAY CONTINUE FOR SEVERAL HOURS AFTER THE INITIAL WAVE ARRIVAL.

THE WAVES WILL FIRST REACH LA JOLLA CALIFORNIA AT 002 PM PST ON FEBRUARY 27. ESTIMATED TSUNAMI ARRIVAL TIMES AND MAPS ALONG WITH SAFETY RULES AND OTHER INFORMATION CAN BE FOUND ON THE WEB SITE: HTTP://www.WCATWC.ARH.NOAA.GOV

AT 1034 PM PACIFIC STANDARD TIME ON FEBRUARY 26 AN EARTHQUAKE WITH PRELIMINARY MAGNITUDE 8.8 OCCURRED NEAR THE COAST OF CENTRAL CHILE. THIS EARTHQUAKE HAS GENERATED A TSUNAMI WHICH COULD CAUSE DAMAGE TO REGIONS IN A WARNING OR ADVISORY.

More information on the tsunami can be found at the NOAA Center for Tsunami Research website: http://nctr.pmel.noaa.gov/chile20100227/


James Roddey
Earth Sciences Information Officer
Oregon Dept. of Geology and Mineral Industries
800 NE Oregon Street, Suite 965, Portland, OR 97232
(971) 673-1543 (direct line) / (503) 807-8343 (cell)
mailto:james.roddey@dogami.state.or.us
http://www.oregongeology.org