Hawaii County Civil Defense audio message at 1:15 a.m. Tuesday (Jan 23)
TSUNAMI MESSAGE NUMBER 3 NWS PACIFIC TSUNAMI WARNING CENTER EWA BEACH HI 110 AM HST TUE JAN 23 2018 TO - EMERGENCY MANAGEMENT IN THE STATE OF HAWAII SUBJECT - TSUNAMI WATCH CANCELLATION THE TSUNAMI WATCH IS CANCELLED FOR THE STATE OF HAWAII EFFECTIVE AT 0110 AM HST. AN EARTHQUAKE HAS OCCURRED WITH THESE PRELIMINARY PARAMETERS NOTE REVISED EARTHQUAKE MAGNITUDE ORIGIN TIME - 1132 PM HST 22 JAN 2018 COORDINATES - 56.0 NORTH 149.2 WEST LOCATION - GULF OF ALASKA MAGNITUDE - 7.9 MOMENT MEASUREMENTS OR REPORTS OF TSUNAMI WAVE ACTIVITY GAUGE LOCATION LAT LON TIME AMPL PER ------------------- ----- ------ ----- --------------- ----- DART 46403 52.6N 156.9W 1024Z 0.03M / 0.1FT 08MIN DART 46410 57.6N 143.8W 1008Z 0.04M / 0.1FT 06MIN DART 46409 55.3N 148.5W 0944Z 0.12M / 0.4FT 04MIN 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. NOTE - DART MEASUREMENTS ARE FROM THE DEEP OCEAN AND THEY ARE GENERALLY MUCH SMALLER THAN WOULD BE COASTAL MEASUREMENTS AT SIMILAR LOCATIONS. EVALUATION BASED ON ALL AVAILABLE DATA THERE IS NO TSUNAMI THREAT TO THE STATE OF HAWAII. THEREFORE... THE TSUNAMI WATCH FOR HAWAII IS NOW CANCELLED. THIS WILL BE THE FINAL MESSAGE ISSUED FOR THIS EVENT UNLESS ADDITIONAL DATA ARE RECEIVED.
Note that warnings/watches/advisories may continue for areas closer to the earthquake’s epicenter. View notices here: wcatwc.arh.noaa.gov
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.