Geoscience Reference
In-Depth Information
Response to the Chilean-Earthquake
Generated Tsunami:
The Hawaii Case Study
EVENT TIMELINE
On Friday, February 26, 2010, at 20:34:14 Hawaii Standard Time (HST) (Saturday, February 27,
2010, at 06:34:14Z; Figure J.1) a magnitude 8.8 earthquake occurred offshore of Maule, Chile, in
position 35.909°S, 72.733°W, approximately 35 km below the surface of the earth.
1
The Paciic
Tsunami Warning Center (PTWC) transmitted its irst tsunami information message to the Civil
Defense in the State of Hawaii (see Figure J.2) 15 minutes after the earthquake at 20:49 HST
(February 27 at 06:49Z)
2
and issued its irst tsunami warning bulletin to the Intergovernmental
Oceanographic Commission (IOC) at 20:46 HST (February 27 at 06:46Z). The West Coast/Alaska
Tsunami Warning Center (WC/ATWC) issued its irst tsunami information statement at 20:49 HST
(February 27 at 06:49Z). The irst tsunami waves arrived at Valparaiso, Chile, approximately
34 minutes after the initial earthquake.
3
Around 06:00 HST (16:35Z) on February 27, evacuation alarms were sounded in low-lying
counties in Hawaii. The irst waves reached Hawaii shortly after 11:35 HST (21:35Z), approxi-
mately 14.5 hours after the initial earthquake. Life in Hawaii started to return to normal at ap-
proximately 14:00 HST (February 28, 00:35Z) when the tsunami warning was lifted.
DESCRIPTION OF TSUNAMI WARNING CENTER MESSAGES
TRANSMITTED TO CIVIL DEFENSE IN THE STATE OF HAWAII
2
The PTWC transmitted its irst tsunami message to Civil Defense in Hawaii at 20:49 HST on
February 26. The message introduced a tsunami advisory, stated that the PTWC had issued an
“expanding regional tsunami warning and watch for parts of the Paciic located closer to the
earthquake” and advised that the earliest arrival of any tsunami wave would be 11:19 HST on
February 27. Updated messages were released approximately every hour. Measurements and
reports of tsunami wave activity were introduced in Message 3 and were continually updated
through Message 20.
Message 6 issued a tsunami warning at 00:46 HST (approximately 11.5 hours before the
forecast arrival of the tsunami). Message 12 (Box J.1) introduced the irst forecasts of combined
wave arrival times and amplitudes (crest to trough) for Hawaii. No additional forecasts were
provided in Messages 13-16. Updated forecasts were provided in Message 17. Message 18 re-
ported the arrival of the tsunami in Hawaii. Message 20 canceled the tsunami warning and was
the inal message issued for the tsunami generated by the Chilean earthquake.
