Categorized | Earthquake, News

Very strong 7.0M quake near Alaska, no tsunami threat to Hawaii

TSUNAMI BULLETIN NUMBER 002
PACIFIC TSUNAMI WARNING CENTER/NOAA/NWS
ISSUED AT 1643Z 30 AUG 2013

THIS BULLETIN APPLIES TO AREAS WITHIN AND BORDERING THE PACIFIC OCEAN AND ADJACENT SEAS…EXCEPT ALASKA…BRITISH COLUMBIA… WASHINGTON…OREGON AND CALIFORNIA.

… TSUNAMI INFORMATION BULLETIN …

THIS BULLETIN IS FOR INFORMATION ONLY. THE EARTHQUAKE LOCATION AND MAGNITUDE ARE UPDATED IN THIS MESSAGE.

THIS BULLETIN IS ISSUED AS ADVICE TO GOVERNMENT AGENCIES. ONLY NATIONAL AND LOCAL GOVERNMENT AGENCIES HAVE THE AUTHORITY TO MAKE DECISIONS REGARDING THE OFFICIAL STATE OF ALERT IN THEIR AREA AND ANY ACTIONS TO BE TAKEN IN RESPONSE.

AN EARTHQUAKE HAS OCCURRED WITH THESE PRELIMINARY PARAMETERS

ORIGIN TIME – 1625Z 30 AUG 2013
COORDINATES – 51.5 NORTH 175.2 WEST
DEPTH – 33 KM
LOCATION – ANDREANOF ISLANDS ALEUTIAN IS. ALASKA
MAGNITUDE – 7.0

EVALUATION

A WIDESPREAD DESTRUCTIVE TSUNAMI THREAT DOES NOT EXIST BASED ON HISTORICAL EARTHQUAKE AND TSUNAMI DATA.

THE WEST COAST AND ALASKA TSUNAMI WARNING CENTER WILL ISSUE INFORMATION REGARDING ANY LOCAL TSUNAMI THREAT TO COASTS NEAR THE EARTHQUAKE EPICENTER.

THIS WILL BE THE ONLY BULLETIN ISSUED FOR THIS EVENT UNLESS ADDITIONAL INFORMATION BECOMES AVAILABLE.

THE WEST COAST/ALASKA TSUNAMI WARNING CENTER WILL ISSUE PRODUCTS FOR ALASKA…BRITISH COLUMBIA…WASHINGTON…OREGON…CALIFORNIA.

Hawaii County Civil Defense audio message

USGS: How large does an earthquake have to be to cause a tsunami?

Magnitudes below 6.5
Earthquakes of this magnitude are very unlikely to trigger a tsunami.

Magnitudes between 6.5 and 7.5
Earthquakes of this size do not usually produce destructive tsunamis. However, small sea level changes may be observed in the vicinity of the epicenter. Tsunamis capable of producing damage or casualties are rare in this magnitude range but have occurred due to secondary effects such as landslides or submarine slumps.

Magnitudes between 7.6 and 7.8
Earthquakes of this size may produce destructive tsunamis especially near the epicenter; at greater distances small sea level changes may be observed. Tsunamis capable of producing damage at great distances are rare in the magnitude range.

Magnitude 7.9 and greater
Destructive local tsunamis are possible near the epicenter, and significant sea level changes and damage may occur in a broader region.

Note that with a magnitude 9.0 earthquake, the probability of an aftershock with a magnitude exceeding 7.5 is not negligible. To date, the largest aftershock recorded has been magnitude 7.1 that did not produce a damaging tsunami.

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