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NOAA NCTR research product
Not an official forecast

The July 29, 2021, Perryville, Alaska tsunami was generated by a Mw 8.2 earthquake (55.325°N 157.841°W), at 2021-07-29 06:15:47 UTC (according to the USGS). The earthquake generated a tsunami that arrived approximately 15 minutes later at the closest DART 46403, located approximately 300 km away from the epicenter. The proximity of DART 46403 to the epicenter resulted in the tsunami signal being contaminated by seismic noise. While DART 46403 has DART 4G capabilities, meaning it should have been able to filter the tsunami signal from the seismic noise, those capabilities were not activated at the time of the event. The next available DART buoy to detect the tsunami was DART 46414, showing a maximum wave amplitude in deep water of just below 5 cm approximately 20 minutes after the earthquake. A DART inversion was performed with data from DART 46414, DART 46409 and DART 46402. The largest coastal tsunami amplitude was ~50 cm and was detected at the Sand Point tide station 3 hours 50 minutes after the earthquake. Model results shown below were created with the NOAA forecast method using the MOST model via inversion of the source with NOAA's TFS (Tsunami Forecast System).

The graphics display preliminary modeling analysis, 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 to the scale bar.

Modeling Results

Maximum wave amplitude distribution
Model amplitudes calculated with the MOST forecast model.
Click to see large image
Propagation animation
Propagation animation
Click for animation.

Preliminary Model

Comparison of the July 29, 2021 Perryville, Alaska tsunami recorded at tsunameter/DARTs and tide gauges with model results computed using the DART-inverted source (red) is presented in the graphics. The DART model time series are obtained from the pre-computed generation/propagation forecast database in real time, after fitting models to tsunami records from the DARTs.

It is noted that all above model results are preliminary. The tsunami source is estimated from inversion of observed waveforms at DARTs using a limited number of unit sources. The discrepancies between model results and tide gauge observation are mostly due to the limited knowledge of the earthquake/tsunami source configuration at this point.

Disclaimer: The models on these pages show the results of ongoing research to enhance tsunami science and to improve NOAA operational tsunami forecasts. These products were developed during or shortly after the tsunami event, are intended for research use, and are not an official forecast. They should not be used as the basis of any public or private policy decisions. Please contact NCTR to find if there are more detailed follow-on analysis results.

Media Contacts

NOAA Public Affairs Monica Allen - 301-734-1123
NWS Public Affairs Susan Buchanan - 301-713-0622

When using information from this page, please credit NOAA / PMEL / Center for Tsunami Research

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