8.8 Earthquake and Pacific Tsunami, February 27, 2010

The pre-dawn magnitude 8.8 earthquake off the coast of Chile on February 27th was one of the most powerful ever recorded. A similar but more powerful quake in 1960 registered a magnitude of 9.5 and generated a deadly tsunami across the Pacific Ocean basin in addition to the immediate damage from the quake itself.

Below is a graphic poster from the US Geological Survey detailing the earthquake.

Click to enlarge image

One of the fears from this most recent quake was that another dangerous tsunami might cross the Pacific. Generally that did not turn out to be the case and wave heights were modest.

The graphics and descriptions below were produced by the NOAA Center for Tsunami Research and provide a picture of the computer driven forecast for this recent event and a comparison to the 1960 tsunami.

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The Chile tsunami was generated by a Mw 8.8 earthquake (35.846°S, 72.719°W ), at 06:34 UTC, 115 km (60 miles) NNE of Concepcion, Chile (according to the USGS). In approximately 3 hours, the tsunami was first recorded at DART® buoy 32412. Forecast results shown below were created with the NOAA forecast method using MOST model with the tsunami source inferred from DART® data. The tsunami waves first arrived at Valparaiso, Chile (approximately 330 km northeast from earthquake epicenter ) earlier than other tide gages, at 0708UTC, about 34 minutes after the earthquake.

The graphics to the left display forecast results, showing qualitative and quantitative information about the tsunami, including tsunami wave interaction with ocean floor bathymetric features, and neighboring coastlines. Tsunami model amplitude information is shown color-coded according the scale bar.

Modeling Results

Energy propagation pattern of the  27 February 2010 tsunami calculated with MOST forecast model. Filled colors show maximum computed tsunami amplitude in cm during 24 hours of wave propagation. Black contours show computed tsunami arrival time.

Another graphical representation of maximum offshore forecast amplitudes

Model amplitudes of the historical 1960 Chilean tsunami from the M 9.5 earthquake calculated with the  MOST forecast model. Filled colors show maximum computed tsunami amplitude in cm during 24 hours of wave propagation. Black contours show computed tsunami arrival time. The source parameters of the earthquake (Mw 9.5) are taken from Kanamori and Ciper [1974].

CREDIT ABOVE: NOAA / PMEL / Center for Tsunami Research

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The edited bulletin below lists the tsunami wave heights at various locations across the Pacific Ocean Basin.

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TSUNAMI BULLETIN NUMBER 018

PACIFIC TSUNAMI WARNING CENTER/NOAA/NWS

ISSUED AT 0012Z 28 FEB 2010

THIS BULLETIN APPLIES TO AREAS WITHIN AND BORDERING THE PACIFIC

OCEAN AND ADJACENT SEAS…EXCEPT ALASKA…BRITISH COLUMBIA…

WASHINGTON…OREGON AND CALIFORNIA.

AN EARTHQUAKE HAS OCCURRED WITH THESE PRELIMINARY PARAMETERS

ORIGIN TIME –  0634Z 27 FEB 2010

COORDINATES –  36.1 SOUTH   72.6 WEST

DEPTH       –   55 KM

LOCATION    –  NEAR COAST OF CENTRAL CHILE

MAGNITUDE   –  8.8

MEASUREMENTS OR REPORTS OF TSUNAMI WAVE ACTIVITY

John Collins

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