Categorized | Earthquake, Featured, News

No tsunami threat to Hawaii from 7.5M Alaska earthquake Friday (Jan 4)

Magnitude
7.5
Date-Time
Saturday, January 05, 2013 at 08:58:16 UTC
Friday, January 04, 2013 at 11:58:16 PM at epicenter
Friday, January 04, 2013 at 10:58:19 PM (HST) – Hawaii Standard (Honolulu)
Location
55.238°N, 134.777°W
Depth
9.9 km (6.2 miles)
Region
SOUTHEASTERN ALASKA
Distances
102 km (63 miles) W of Craig, Alaska
303 km (188 miles) WNW of Prince Rupert, Canada
335 km (208 miles) S of Juneau, Alaska
402 km (249 miles) WNW of Terrace, Canada

TSUNAMI INFORMATION STATEMENT NUMBER   2
NWS PACIFIC TSUNAMI WARNING CENTER EWA BEACH HI
1146 PM HST FRI JAN 04 2013

TO - CIVIL DEFENSE IN THE STATE OF HAWAII

SUBJECT - TSUNAMI INFORMATION STATEMENT

THIS STATEMENT IS FOR INFORMATION ONLY. NO ACTION REQUIRED.

AN EARTHQUAKE HAS OCCURRED WITH THESE PRELIMINARY PARAMETERS

   ORIGIN TIME - 1058 PM HST 04 JAN 2013
   COORDINATES - 55.3 NORTH  134.9 WEST
   LOCATION    - SOUTHEASTERN ALASKA
   MAGNITUDE   - 7.6  MOMENT


MEASUREMENTS OR REPORTS OF TSUNAMI WAVE ACTIVITY

 GAUGE LOCATION        LAT   LON    TIME        AMPL         PER
 -------------------  ----- ------  -----  ---------------  -----
 PORT ALEXANDER AK    56.2N 134.6W  0929Z   0.13M /  0.4FT  10MIN
 LAT  - LATITUDE (N-NORTH, S-SOUTH)
 LON  - LONGITUDE (E-EAST, W-WEST)
 TIME - TIME OF THE MEASUREMENT (Z IS UTC IS GREENWICH TIME)
 AMPL - TSUNAMI AMPLITUDE MEASURED RELATIVE TO NORMAL SEA LEVEL.
        IT IS ...NOT... CREST-TO-TROUGH WAVE HEIGHT.
        VALUES ARE GIVEN IN BOTH METERS(M) AND FEET(FT).
 PER  - PERIOD OF TIME IN MINUTES(MIN) FROM ONE WAVE TO THE NEXT.

EVALUATION

 THE WEST COAST AND ALASKA TSUNAMI WARNING CENTER HAS ISSUED A
 REGIONAL TSUNAMI WARNING AND/OR WATCH AND/OR ADVISORY FOR OTHER
 PARTS OF THE PACIFIC LOCATED CLOSER TO THE EARTHQUAKE. BASED ON
 ALL AVAILABLE DATA THERE IS NO DESTRUCTIVE TSUNAMI THREAT TO
 HAWAII.

 HOWEVER... SOME COASTAL AREAS IN HAWAII COULD EXPERIENCE SMALL
 NON-DESTRUCTIVE SEA LEVEL CHANGES AND STRONG OR UNUSUAL CURRENTS
 LASTING UP TO SEVERAL HOURS. THE ESTIMATED TIME SUCH EFFECTS
 MIGHT BEGIN IS

0428 AM HST SAT 05 JAN 2013

THIS WILL BE THE ONLY STATEMENT ISSUED FOR THIS EVENT UNLESS
ADDITIONAL DATA ARE RECEIVED.

Tsunami time travel map. Hawaii could experience small non-destructive sea level changes and strong or unusual currents starting at 4:28 a.m. Saturday (Jan 5).

Tsunami time travel map. Hawaii could experience small non-destructive sea level changes and strong or unusual currents starting at 4:28 a.m. Saturday (Jan 5).


West Coast/Alaska Tsunami Warning Center Bulletin #4

BULLETIN
PUBLIC TSUNAMI MESSAGE NUMBER 4
NWS WEST COAST/ALASKA TSUNAMI WARNING CENTER PALMER AK
158 AM AKST SAT JAN 5 2013

...THE TSUNAMI WARNING IS CANCELLED...


CANCELLATIONS
-------------
 * THE TSUNAMI WARNING IS CANCELED FOR THE COASTAL AREAS OF
   BRITISH COLUMBIA AND ALASKA FROM THE NORTH TIP OF VANCOUVER
   ISLAND BRITISH COLUMBIA TO CAPE FAIRWEATHER ALASKA/LOCATED
   80 MILES SE OF YAKUTAT/


IMPACTS - UPDATED
-----------------
 * A TSUNAMI WAS GENERATED DURING THIS EVENT BUT NO LONGER
   POSES A THREAT.

 * SOME AREAS MAY CONTINUE TO SEE SMALL SEA LEVEL CHANGES.

 * THE DETERMINATION TO RE-OCCUPY HAZARD ZONES MUST BE MADE BY
   LOCAL OFFICIALS.


RECOMMENDED ACTIONS - UPDATED
-----------------------------
 * DO NOT RE-OCCUPY HAZARD ZONES UNTIL LOCAL EMERGENCY OFFICIALS
   INDICATE IT IS SAFE TO DO SO.


OBSERVATIONS OF TSUNAMI ACTIVITY - UPDATED
------------------------------------------
                                  TIME             OBSERVED MAX
 SITE                         OF MEASUREMENT       TSUNAMI HEIGHT
 ---------------------------- ---------------      --------------
 PORT ALEXANDER  AK           1026 UTC  01-05        00.5FT
 SITKA  AK                    1041 UTC  01-05        00.3FT

 HEIGHT - OBSERVED MAX TSUNAMI HEIGHT IS THE WATER LEVEL ABOVE THE
          TIDE LEVEL AT THE TIME OF MEASUREMENT.

 DEEP OCEAN PRESSURE SENSORS DID NOT RECORD A TSUNAMI.


NEXT UPDATE AND ADDITIONAL INFORMATION
--------------------------------------
 * THIS WILL BE THE LAST WEST COAST/ALASKA TSUNAMI WARNING CENTER
   BULLETIN ISSUED FOR THIS EVENT.

 * REFER TO THE INTERNET SITE WCATWC.ARH.NOAA.GOV FOR MORE
   INFORMATION.

 * PACIFIC COASTAL REGIONS OUTSIDE CALIFORNIA... OREGON...
   WASHINGTON... BRITISH COLUMBIA AND ALASKA SHOULD REFER TO THE
   PACIFIC TSUNAMI WARNING CENTER MESSAGES FOR INFORMATION AT
   PTWC.WEATHER.GOV.
Tsunami energy map for 7.5 magnitude Alaska earthquake on Friday (Jan 4).

Tsunami energy map for 7.5 magnitude Alaska earthquake on Friday (Jan 4).

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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