In general, if you think a tsunami may be coming, the
ground shakes under your feet or you hear there is a
warning, you should move
quickly to higher ground.
If you are on land:
- If you are at home and hear there is a tsunami
warning, you should make sure your family is
aware of the warning. Your family should evacuate
your house if you live in an evacuation zone.
Move to the
evacuation site or to any safe place outside your
evacuation zone. Follow the advice of local emergency
and law enforcement.
- If you are at the beach or near the ocean and you
feel the ground shake, move immediately to higher
ground, DO NOT wait for a warning to be
announced. Stay away from rivers and streams that
lead to the ocean as you would stay away from the
beach and ocean. A regional
tsunami from a local earthquake could strike some
areas before a tsunami warning could be announced.
- Tsunamis generated in distant locations will
generally give people enough time to move to higher
ground. For locally-generated tsunamis, where you
might feel the ground shake, you may only have a few
minutes to move to higher ground.
If you are on a boat:
Since tsunami wave activity is unperceptible
do not return to port if you are at sea and
a tsunami warning has been issued for your area.
Tsunamis can cause huge changes in water level.
If there is time to move your boat or ship from port to
deep water (after a tsunami warning has been issued),
you should take the following considerations:
- Most large harbors and ports are under the control
of a harbor authority and/or a vessel traffic system.
They direct operations during periods of
increased readiness (should a tsunami be expected),
including the forced movement of vessels if deemed
necessary. Keep in contact with the authorities should
a forced movement of vessel be directed.
- Smaller ports may not be under the control of a
harbor authority. If you are aware there is a tsunami
warning and you have time to move your vessel to deep
water, then you may want to do so in an orderly manner,
in consideration of other vessels. Owners of small
boats may find it safest to leave their boat at the
pier and physically move to higher ground,
particularly in the event of a locally-generated
tsunami. Concurrent severe weather conditions
(rough seas outside of safe harbor) could present a
greater hazardous situation to small boats, so
physically moving yourself to higher ground may be
the only option.
Overview of the Tsunami Warning
System
The Tsunami Warning System (TWS) in the Pacific,
comprised of 26 participating international
Member States, has the
functions of monitoring seismological and tidal
stations throughout the Pacific Basin to evaluate
potentially tsunamigenic earthquakes and disseminating
tsunami warning information. The Pacific Tsunami
Warning Center (PTWC) is the operational center of the
Pacific TWS. Located near Honolulu, Hawaii, PTWC
provides tsunami warning information to national
authorities in the Pacific Basin.
Tsunami Warning Centers
As part of an international cooperative effort to save
lives and protect property, the National Oceanic and Atmospheric Administration
's (NOAA)
National Weather Service operates two tsunami
warning centers. The Alaska Tsunami Warning Center
(ATWC) in
Palmer, Alaska, serves as the regional Tsunami Warning
Center for Alaska, British Columbia, Washington, Oregon,
and California.
The Pacific Tsunami Warning Center in Ewa Beach, Hawaii,
serves as the regional Tsunami Warning Center for
Hawaii and as a national/international warning center
for tsunamis that pose a Pacific-wide threat.
This international warning effort became a formal
arrangement in 1965 when PTWC assumed the international
warning responsibilities of the Pacific Tsunami
Warning System (PTWS). The PTWS is composed of 26
international Member States
that are organized as the International Coordination
Group for the Tsunami Warning System in the Pacific.
Tsunami Watch and Warning
Determination
The objective of the PTWS is to detect, locate,
and determine the magnitude of potentially
tsunamigenic earthquakes occurring in the Pacific
Basin or its immediate margins. Earthquake information
is provided by seismic stations operated by PTWC, ATWC,
the U.S. Geological Survey's
National
Earthquake Information Center and international
sources. If the location and magnitude of an
earthquake meet the known criteria for generation
of a tsunami, a tsunami warning is issued to warn of
an imminent tsunami hazard. The warning includes
predicted tsunami arrival times at selected coastal
communities within the geographic area defined by the
maximum distance the tsunami could travel in a few
hours. A tsunami watch with additional predicted
tsunami arrival times is issued for a geographic area
defined by the distance the tsunami could travel in
a subsequent time period.
If a significant tsunami is detected by sea-level mo
nitoring instrumentation, the tsunami warning is
extended to the entire Pacific Basin. Sea-level
(or tidal) information is provided by NOAA's
National Ocean Service, PTWC, ATWC,
university monitoring networks and other
participating nations of the PTWS. The
International Tsunami
Information Center, part of the Intergovernmental
Oceanographic Commission, monitors and evaluates the
performance and effectiveness of the Pacific Tsunami
Warning System. This effort encourages the most
effective data collection, data analysis, tsunami
impact assessment and warning dissemination to all
TWS participants.
Tsunami Warning Dispathching
Tsunami watch, warning, and information bulletins are
dispatched to appropriate emergency officials and
the general public by a variety of communication
methods.
- Tsunami watch, warning and information bulletins
issued by PTWC and
ATWC are
disseminated to local, state, national and
international users as well as the media. These users,
in turn, dispatch the tsunami information to the
public, generally over commercial radio and television
channels.
- The NOAA Weather Radio System, based on a large
number of VHF transmitter sites, provides direct
broadcast of tsunami information to the public.
- The
US Coast Guard also broadcasts urgent marine
warnings and related tsunami information to coastal
users equipped with medium frequency (MF) and very
high frequency (VHF) marine radios.
- Local authorities and emergency managers are
responsible for formulating and executing evacuation
plans for areas under a tsunami warning. The public
should stay-tuned to the local media for evacuation
orders should a tsunami warning be issued. And, the
public should NOT RETURN to low-lying areas until the
tsunami threat has passed and the "all clear" is
announced by the local authorities.
Information from: http://www.geo.mtu.edu/department/classes/ge404/tsunami/
