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Unformatted text preview: Revised, 2002
R evised, P R E S E N T E D B Y: IOC U. S. NATIONAL OCEANIC & ATMOSPHERIC ADMINISTRATION (NOAA)
UNESCO/INTERGOVERNMENTAL OCEANOGRAPHIC COMMISSION (IOC)
INTERNATIONAL TSUNAMI INFORMATION CENTER (ITIC)
LABORATOIRE DE GEOPHYSIQUE, FRANCE (LDG) and 2200 lives in the 1998 Aitape, Papua New Guinea
tsunamis. Property damage was nearly one billion
United States (U.S.) dollars. Although 80% of the
tsunamis occur in the Paciﬁc, they can also threaten
coastlines of countries in other regions, including the
Indian Ocean, Mediterranean Sea, Caribbean region,
and even the Atlantic Ocean.
At the Richard H. Hagemeyer Paciﬁc Tsunami Warning
Center (PTWC), the operational center of the Tsunami The purpose of this brochure is to
increase awareness and knowledge of
tsunamis. Please share what you learn;
knowing the right information may save
your life and the lives of those you love. Left: Computer model of the initial water surface
changes at the time the July 30, 1995, Chilean
tsunami was generated. A is Antofagasta, Chile.
Right: Computer model of the same tsunami, three
hours after it was generated. The phenomenon we call "tsunami" (soo-NAHmee) is a series of traveling ocean waves of extremely long length generated primarily by earthquakes
occurring below or near the ocean ﬂoor. Underwater
volcanic eruptions and landslides can also generate tsunamis. In the deep ocean, the tsunami waves
propagate across the deep ocean with a speed
exceeding 800 kilometers per hour ([km], ~500 miles
per hour), and a wave height of only a few tens of
centimeters (1 foot [ft]) or less. Tsunami waves are
distinguished from ordinary ocean waves by their
great length between wave crests, often exceeding
Hilo Harbor, Hawaii, April 1, 1946, Aleutian Islands earthquake.
a 100 km (60 miles [mi]) or more in the deep ocean, Photo taken from the vessel Brigham Victory of tsunami breaking
and by the time between these crests, ranging from over Pier 1. The gentleman on the left did not survive. (NOAA)
10 minutes to an hour.
Warning System in the Paciﬁc (TWSP), scientists monAs they reach the shallow waters of the coast, the waves
itor seismological and water level stations throughout
slow down and the water can pile up into a wall of destructhe Paciﬁc Basin, evaluate potentially tsunamigenic
tion tens of meters (30 ft) or more in height. The effect can
earthquakes, monitor tsunami waves, and disseminate
be ampliﬁed where a bay, harbor or lagoon funnels the wave
tsunami warning information. Located near Honolulu,
as it moves inland. Large tsunamis have been known to
Hawaii, PTWC provides tsunami warning information to
rise over 30 meters (100 ft). Even a tsunami 3–6 meters
national authorities in the Paciﬁc Basin. National or
(m) high can be very destructive and cause many deaths
Regional Warning Centers are also operating in Japan,
French Polynesia, Chile, and Russia, in addition to the
Tsunamis are a threat to life and property for all coastal
residents living near the ocean. During the 1990s, over
The International Tsunami Information Center, host4,000 people were killed by 10 tsunamis, including more
ed by the U.S. and located in Honolulu, Hawaii, at
than 1000 lives lost in the 1992 Flores region, Indonesia,
NOAA/National Weather Service Pacific Region
Headquarters, monitors and evaluates the performance
and effectiveness of the TWSP on an everyday basis. 1 sunamis, also called seismic sea wave
or incorrectly tidal waves, are caused
generally by earthquakes, less
commonly by submarine landslides,
infrequently by submarine volcanic eruptions
and very rarely by large meteorite impacts in
the ocean. Submarine volcanic eruptions have
the potential to produce truly awesome tsunami
waves. The Great Krakatau Volcanic Eruption
of 1883 generated giant waves reaching heights
of 40 meters above sea-level, killing more than
30,000 people and wiping out numerous
coastal villages. T All oceanic regions of the world can experience
tsunamis, but in the Paciﬁc Ocean and it's
marginal seas, there is a much more frequent
occurrence of large, destructive tsunamis
because of the many large earthquakes along
the margins of the Paciﬁc Ocean. PLATE TECTONICS
Plate Tectonic theory is based on an earth model characterized by a small number of lithospheric plates, 70 to
250 km (40 to 150 mi) thick, that ﬂoat on a viscous underlayer called the asthenosphere. These plates, which
cover the entire surface of the earth and contain both the
continents and seaﬂoor, move relative to each other at
rates of up to ten cm/year (several inches/year). The
region where two plates come in contact is called a plate
boundary, and the way in which one plate moves relative to another determines the type of boundary: spreading, where the two plates move away from each other;
subduction, where the two plates move toward each
other and one slides beneath the other; and transform,
where the two plates slide horizontally past each other.
Subduction zones are characterized by deep ocean
trenches, and the volcanic islands or volcanic mountain chains associated with the
many subduction zones around the Paciﬁc
rim are sometimes called the Ring of Fire. EARTHQUAKES AND
An earthquake can be caused by volcanic
activity, but most are generated by movements along fault zones associated with the
plate boundaries. Most strong earthquakes,
representing 80% of the total energy 2 Tsunami generated by May 26, 1983, Japan Sea earthquake approaching Okushiri Island, Japan. The runup
here was 5.9 m (19 ft), but runups as high as 14 m (45 ft)
were measured in Akita Prefecture 100 km east of the epicenter. Altogether, 100 people lost their lives, including
three people in South Korea where the wave arrived
about 1.5 hours after the earthquake. (Tokai Univ. report) released worldwide by earthquakes, occur in subduction
zones where an oceanic plate slides under a continental
plate or another younger oceanic plate.
Not all earthquakes generate tsunamis. To generate
a tsunami, the fault where the earthquake occurs must be
underneath or near the ocean, and cause vertical movement of the seaﬂoor (up to several meters) over a large
area (up to a hundred thousand square kilometers).
Shallow focus earthquakes (depth less 70 km or 42 mi)
along subduction zones are responsible for most destructive tsunamis. The amount of vertical and horizontal
motion of the sea ﬂoor, the area over which it occurs, the
simultaneous occurrence of slumping of underwater sediments due to the shaking, and the efficiency with which
energy is transferred from the earth’s crust to the ocean
water are all part of the tsunami generation mechanism. TSUNAMI EARTHQUAKES
The September 2, 1992 earthquake (magnitude 7.2)
was barely felt by residents along the coast of Nicaragua.
Located well off-shore, its intensity, the severity of shaking on a scale of I to XII, was mostly II along the coast,
and reached III at only a few places. Twenty to 70 minutes after the earthquake occurred, a tsunami struck the
coast of Nicaragua with wave amplitudes 4 m (13 ft)
above normal sea level in most places and a maximum
runup height of 10.7 m (35 ft). The waves caught coastal
residents by complete surprise and caused many casualties and considerable property damage.
This tsunami was caused by a tsunami earthquake —
an earthquake that produces an unusually large tsuna- mi relative to the earthquake magnitude. Tsunami earthquakes are characterized by a very shallow focus, fault
dislocations greater than several meters, and fault surfaces that are smaller than for a normal earthquake.
They are also slow earthquakes, with slippage along
the fault beneath the sea ﬂoor occurring more slowly than
it would in a normal earthquake. The only known method
to quickly recognize a tsunami earthquake is to estimate
a parameter called the seismic moment using very long
period seismic waves (more than 50 seconds / cycle). Two
other destructive and deadly tsunamis from tsunami earthquakes have occurred in recent years in Java, Indonesia
(June 2, 1994) and Peru (February 21, 1996). The earthquake focus is the point in the
earth where the rupture ﬁrst occurs and
where the ﬁrst seismic waves originate.
The epicenter is the point on the Earth’s
surface directly above the focus. El Transito, Nicaragua, September 1, 1992. Ninemeter high waves destroyed the town, killing 16 and
injuring 151 in this coastal community of 1,000 people. The ﬁrst wave was thought to be small providing time for people to escape the destructive second
and third waves. More than 40,000 people were affected by the loss of their homes or means of income.
(Harry Yeh, Univ. of Washington) The magnitude is the logarithm of the maximum amplitude of one the seismic waves
(P, S, Rayleigh or Love surface waves)
recorded by the seismometer; an increase
in one unit of magnitude corresponds to
a factor of 10 increase in amplitude. 3 TSUNAMI: THE RELATION
WITH THE SEISMIC SOURCE FOCUS n the deep ocean, destructive tsunamis can be small – often
only a few tens of centimeters or less in height – and cannot
be seen nor felt on ships at sea. But as the tsunami reaches
shallower coastal waters, wave height can increase rapidly.
Sometimes, coastal waters are drawn out into the ocean just
before the tsunami strikes. When this occurs, more shoreline may
be exposed than even at the lowest tide. This major withdrawal
of the sea should be taken as a warning of the tsunami waves that
will follow. I Tsunami Speed is reduced in shallow water as wave height increases rapidly.
10.6 km 213 km 23 km 10 m
50 m 4000 m Depth Velocity Wave length (meters) (km/h) (km) 7000
10.6 In the open ocean a tsunami is less than a few tens of centimeters (1 ft) high
at the surface, but its wave height increases rapidly in shallow water.
Tsunami wave energy extends from the surface to the bottom in even the
deepest waters. As the tsunami attacks the coastline, the wave energy is
compressed into a much shorter distance and a much shallower depth, creating destructive, life-threatening waves. PACIFIC-WIDE AND REGIONAL TSUNAMIS
The last large tsunami that caused widespread death and destruction throughout the
Paciﬁc was generated by an earthquake located off the coast of Chile in 1960. It caused
loss of life and property damage not only
along the Chile coast but in Hawaii and as far
away as Japan. The Great Alaskan
Earthquake of 1964 produced deadly tsunami waves in Alaska, Oregon and California.
In July 1993, a tsunami generated in the
Sea of Japan killed over 120 people in Japan.
Damage also occurred in Korea and
Russia but not in other countries since
the tsunami wave energy was conﬁned
within the Sea of Japan. The 1993 Japan
Sea tsunami is known as a "regional
event" since its impact was conﬁned to
a relatively small area. For people living along the northwestern coast of
Japan, the tsunami waves followed the
earthquake within a few minutes.
During the 1990s, destructive regional tsunamis also occurred in Nicaragua,
Indonesia, the Philippines, Papua New
Guinea, and Peru, killing thousands of
people. Others caused property damage in Chile and Mexico. Some damage
also occurred in the far field in the Marquesas Islands (French Polynesia) from
the July 30, 1995, Chilean and February 21,
1996, Peruvian tsunamis.
In less than a day, tsunamis can travel
from one side of the Paciﬁc to the other.
However, people living near areas where
large earthquakes occur may ﬁnd that the
tsunami waves will reach their shores within
minutes of the earthquake. For these reasons, the tsunami threat to many areas, e.g.,
Alaska, the Philippines, Japan and the U.S.
West Coast, can be immediate (for tsunamis
from nearby earthquakes which take only a
few minutes to reach coastal areas) or less
urgent (for tsunamis from distant earthquakes
which take from three to 22 hrs to reach
coastal areas). Pagaraman, Babi Island, Indonesia, December 12, 1992.
Tsunamis washed away everything leaving only white beach
sand. Seven hundred people were killed by the earthquake
and ensuing tsunami. (Harry Yeh, Univ. of Washington) 4 120° E 150° E
180° E 150° W 120° W 90° W HOW FAST? HOW BIG? Epicenter Where the ocean is over
6,000 m deep, unnoticed
tsunami waves can travel at the speed of a commercial jet plane, over
800 km per hour (~500
mi per hour). They can
move from one side of
the Paciﬁc Ocean to the
other in less than a day.
This great speed makes
it important to be aware
of the tsunami as soon
as it is generated.
Scientists can predict
when a tsunami will
arrive at various places
by knowing the source
characteristics of the
Calculated tsunami travel times for an earthquake occurring
earthquake that generoff the coast of Chile. Each concentric curve represents one
ated the tsunami and
hour of tsunami travel time.
the characteristics of the
seaﬂoor along the paths to those places. Tsunamis travel much slower in shallower
coastal waters where their wave heights begin to increase dramatically.
60° Offshore and coastal features can determine the size and impact of tsunami waves. Reefs,
bays, entrances to rivers, undersea features and the slope of the beach all help to modify the tsunami as it attacks the coastline. When the tsunami reaches the coast and moves
inland, the water level can rise many meters. In extreme cases, water level has risen to
more than 15 m (50 ft) for tsunamis of distant origin and over 30 m (100 ft) for tsunami
waves generated near the earthquake’s epicenter. The ﬁrst wave may not be the largest
in the series of waves. One coastal community may see no damaging wave activity while
in another nearby community destructive waves can be large and violent. The ﬂooding
can extend inland by 300 m (~1000 ft) or more, covering large expanses of land with water
and debris. Tide Stations Hourly Contour Intervals HOW FREQUENT?
Since scientists cannot predict when earthquakes will occur, they cannot determine exactly when a tsunami will be generated. However, by looking at past historical tsunamis, scientists know where tsunamis are most likely to be generated. Past tsunami height measurements are useful in predicting future tsunami impact and ﬂooding limits at speciﬁc coastal
locations and communities. Historical tsunami research may prove helpful in analyzing
the frequency of occurrence of tsunamis. During each of the last ﬁve centuries, there were
three to four Paciﬁc-wide tsunamis, most of them generated off the Chilean coasts.
May 26, 1983
train of shortperiod waves.
report) During post-tsunami ﬁeld surveys, inundation and runup measurements are taken to describe the tsunami effects. Inundation
is deﬁned as the maximum horizontal distance inland that a tsunami penetrates. Runup is the maximum vertical height above mean
sea level that the sea surface attains during a tsunami. Actual
tsunami wave heights can be measured from the amplitude of
the wave signals seen on sea level or tide gauge instruments. 5 Kodiak, Alaska. The March 27, 1964, tsunami
caused 21 deaths and $30 million U.S. dollars
in damage in and near the city of Kodiak. International Tsunami Information Center (ITIC)
ITIC, supported in part by the IOC, monitors and evaluates the performance
and effectiveness of the TWSP. This effort encourages the most effective
data collection, data analysis, tsunami impact assessment, and warning dissemination to all TWSP participants, and ensures continuing efforts in tsunami awareness and training, in part through its Tsunami Newsletter, Bulletin
Board listserve, Visiting Experts Program, and the ITSU/ITIC Tsunami
Information Web Portal. ITIC also provides technical assistance to support
the development of and improvements to national tsunami warning systems. The Wave. Painting by Lucas Rawah of Aitape, done to commemorate the July 17, 1998, Papua New Guinea event. A magnitude 7.1
earthquake is thought to have triggered a submarine landslide generating a tsunami that destroyed entire villages along the Aitape coast. 6 TSUNAMI WARNING CENTERS
The Richard H. Hagemeyer Paciﬁc Tsunami Warning
Center (PTWC) serves as the international warning
center for tsunamis that pose a Paciﬁc-wide threat.
This international warning effort became a formal
arrangement in 1965 when PTWC assumed responsibility as the operational center for the Tsunami
Warning System in the Paciﬁc (TWSP). The ICG/ITSU,
a subsidiary body of the IOC comprised of 25 international Member States, oversees TWSP operations
and facilitates coordination and cooperation in all other
international tsunami mitigation activities.
The initial objective of PTWC is to detect, locate
and determine the seismic parameters of potentially
tsunamigenic earthquakes occurring in the Paciﬁc
Basin or its immediate margins. To accomplish this,
it continuously receives seismographic data from more
than 150 stations around the Paciﬁc through cooperative data exchanges with the U.S. Geological Survey,
Incorporated Research Institutions for Seismology,
International Deployment of Accelerometers, GEOSCOPE, the U.S. West Coast/Alaska Tsunami
Warning Center (WC/ATWC), and other international agencies running seismographic stations and networks.
If the earthquake location, depth, and magnitude
criteria needed to generate a tsunami are met, a
tsunami warning is issued to warn of an imminent
tsunami hazard. Initial warnings apply only to areas
the tsunami could reach within a few hours and bulletins include the predicted tsunami arrival times at
selected coastal communities within those areas.
Communities located outside those areas are put into
either a tsunami watch or advisory status. Information about the IOC Warning center scientists then monitor incoming
sea level data to determine whether a tsunami has
occurred. If a signiﬁcant tsunami with long-range
destructive potential is detected, the tsunami warning
is extended to the entire Paciﬁc Basin. PTWC receives
sea level data from more than 100 stations through
cooperative data exchanges with the U.S. National
Ocean Service, WC/ATWC, the University of Hawaii
Sea Level Center, Chile, Australia, Japan, Russia,
and other international sources. Tsunami warnings,
watches, and information bulletins are disseminated
to appropriate emergency officials and the general
public by a variety of communication methods.
In addition, individual countries may operate National
or Regional Warning Centers to provide warning information on regional or local tsunami threats. The Japan
Meteorological Agency provides tsunami warnings to
Japan, and additionally to Korea and Russia for events
occurring in the Sea of Japan or East Sea. The Centre
Polynesien de Prevention des Tsunamis provides
warnings in French Polynesia, and Chile (Sistema
Nacional de Alarma de Maremotos) and Russia
(Russian Hydrometeorological Service) operate
national warning systems.
In the United States, WC/ATWC provides tsunami
warnings to the U.S. West Coast and Canada, and
PTWC provides tsunami warnings to Hawaii and to
all other U.S. interests in the Paciﬁc. Other countries,
including Australia, Colombia, Nicaragua, Peru, and
Korea, are also developing warning capabilities. 7 The Intergovernmental Oceanographic Commission
(IOC), a body with functional autonomy within the United
Nations Educational, Scientiﬁc and Cultural Organization
(UNESCO), was established to promote marine scientiﬁc
investigations and related ocean services with a view
to learning more about the nature and resources of the
ocean through the concerted actions of its members.
In general terms, the functions of the IOC among
others are: to develop, recommend and coordinate
international programs for scientiﬁc investigation of
the oceans and related ocean services; to promote and
make recommendations for the exchange of
oceanographic data and the publication and
dissemination of results of scientiﬁc investigation of
the oceans; to promote and coordinate the development
and transfer of marine science and its technology; to
make recommendations to strengthen education and
training and to promote scientiﬁc investigation of the
oceans and application of the results thereof for the
beneﬁt of all mankind. 129 Member States are currently
part of the IOC. The Assembly meets every two years
at the UNESCO headquarters in Paris, France.
The IOC consists of an Assembly, an Executive
Council, a Secretariat and such subsidiary bodies as it
may establish. Under this last concept, the Commission
creates, for the examination and execution of speciﬁc
projects, committees or other subsidiary bodies
composed of Member States interested in such projects.
This is the case for the International Coordination Group
for the Tsunami Warning System in the Pacific
(ICG/ITSU). T DEEP-OCEAN ASSESSMENT AND
REPORTING ON TSUNAMIS (DART System)
VIA SATELLITE WARNING
MODULE IC L
SENSOR April 1, 1946. People ﬂee as a tsunami attacks
downtown Hilo, Hawaii (Bishop Museum) NOAA/PMEL INDEPENDENT 3 COMPONENT
BROAD -BAND SEISMIC STATION Warning Dissemination
- Tsunami warnings, watches, and information bulletins issued by PTWC and other Regional Centers
are disseminated to local, state, national, and international users as well as the media. These users,
usually government authorities, in turn disseminate
the tsunami information to the public, generally over
commercial radio and television channels.
- With the help of modern communication facilities,
direct broadcast of tsunami information is urgently provided to the public. DASE/LDG 8 - 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. RUN-UP MAXIMUM The seismic moment Mo is related by: Mo=µ S D where µ is
the rigidity, S the fault area and D the mean dislocation. 9 ONA
B UKU is not accurate above 7.5, the seismic moment
and the source duration are now used to better deﬁne the amount of energy released and
the tsunami generation potential. Real-time
determination of the depth of the earthquake,
type of faulting, and extent of slippage will
signiﬁcantly improve the warning centers’ ability to identify the likelihood of a threatening
Tsunami generation is initiated by threedimensional deformation of the ocean bottom
due to movement of the fault. Better characterizations of the earthquake fault mechanism will produce more realistic numerical models of propagation,
runup, and inundation. Currently, numerical models of
propagation generally use an implicit-in-time ﬁnite difference method.
Tsunami inundation models, deﬁning the extent of
coastal ﬂooding, are an integral aspect of tsunami hazard and preparedness planning. Using worst case inundation scenarios, these models are critical to deﬁning
evacuation zones and routes so that coastal communities can be evacuated quickly when a tsunami warning
has been issued. TAH
A With the broad availability of relatively inexpensive yet
powerful computers and desktop workstations, there is
growing interest and activity in tsunami research. Using
the latest in computer technology, scientists are able to
numerically model tsunami generation, open ocean propagation, and coastal runup.
Ocean-bottom pressure sensors, able to measure
tsunamis in the open ocean, are providing important data
on the propagation of tsunamis in deep water, and satellite communications have enabled these data to be used
in real time to detect and conﬁrm that a tsunami has been
generated in the deep ocean. NOAA’s Paciﬁc Marine
Environmental Laboratory has pioneered the development of these tsunami detection buoys, and by the end
of 2003, seven DART buoys will be in operation in the
northern and eastern Paciﬁc and available for use by the
tsunami warning centers. Better equipment and numerical modeling methods are helping scientists to better
understand the mechanism of tsunami generation.
Seismologists, studying the dynamics of earthquakes
with broad band seismometers (20 to 0.003 Hertz), are
formulating new methods to analyze earthquake motion
and the amount of energy released. Where the traditional Richter (surface wave) magnitude of earthquakes BAY Tsunami Research Activities LEFT: July 30, 1995,
Model results showing the maximum runup and inundation relative to the normal
sea level and shoreline (white line) at
Tahauku Bay, Hiva
Hoa, in the
Two small boats sunk
in Tahauku Bay as a
result of this event.
BELOW: Model of the
tsunami in the southeast Paciﬁc, nine hrs
after its generation. 5 WHAT YOU SHOULD DO
- Tsunamis that strike coastal locations in the Paciﬁc Ocean
Basin are almost always caused by earthquakes. These
earthquakes might occur far away or near where you live.
- Some tsunamis can be very large. In coastal areas their
height can be as great as 10 m or more (30 m in extreme
cases), and they can move inland several hundred meters.
- All low lying coastal areas can be struck by tsunamis.
- A tsunami consists of a series of waves with crests arriving
every 10 to 60 minutes. Often the ﬁrst wave may not be the
largest. The danger from a tsunami can last for several hours
after the arrival of the ﬁrst wave. Tsunami waves typically do
not curl and break, so do not try to surf a tsunami!
- Tsunamis can move faster than a person can run.
- Sometimes a tsunami initially causes the water near shore
to recede, exposing the ocean ﬂoor.
- The force of some tsunamis is enormous. Large rocks
weighing several tons, along with boats and other debris, can
be moved inland hundreds of meters by tsunami wave activity, and homes and buildings destroyed. All this material and
water move with great force, and can kill or injure people.
- Tsunamis can occur at any time, day or night.
- Tsunamis can travel up rivers and streams from the ocean.
- Tsunami can easily wrap around islands and be just as dangerous on coasts not facing the source of the tsunami. Be aware of tsunami facts.
This knowledge could save your life!
Share this knowledge with your
relatives and friends.
It could save their lives!
- If you are in school and you hear there is a tsunami warning, you should follow the advice of teachers and other school personnel.
- If you are at home and hear there is a tsunami
warning, you should make sure your entire family
is aware of the warning. Your family should evacuate your house if you live in a tsunami evacuation
zone. Move in an orderly, calm, and safe manner
to the evacuation site or to any safe place outside
your evacuation zone. Follow the advice of local
emergency and law enforcement authorities.
- If you are at the beach or near the ocean and you
feel the earth shake, move immediately to higher
ground. DO NOT wait for a tsunami 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 if there is a tsunami. A regional tsunami from a local earthquake could strike some
areas before a tsunami warning can 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. 10 - High, multi-story, reinforced concrete hotels are
located in many low-lying coastal areas. The upper
ﬂoors of these hotels can provide a safe place to
ﬁnd refuge should there be a tsunami warning and
you cannot move quickly inland to higher ground.
Local Civil Defense procedures may, however, not
allow this type of evacuation in your area. Homes
and small buildings located in low lying coastal
areas are not designed to withstand tsunami
impacts. Do not stay in these structures should
there be a tsunami warning.
- Offshore reefs and shallow areas may help break
the force of tsunami waves, but large and dangerous waves can still be a threat to coastal residents
in these areas. Staying away from all low-lying
coastal areas is the safest advice when there is a
tsunami warning. Oga Aquarium,
flooded stranding car during
the May 26,
Japan) IF YOU ARE ON A SHIP OR BOAT
- Since tsunami wave activity is imperceptible in
the open ocean, do not return to port if you are at
sea and a tsunami warning has been issued for
your area. Tsunamis can cause rapid changes
in water level and unpredictable dangerous currents in harbors and ports.
- If there is time to move your boat or ship from
port to deep water (after you know a tsunami warning has been issued), you should weigh the following considerations:
- Most large harbors and ports are under the control of a harbor authority and/or a vessel traffic
system. These authorities 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
vessels 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 the harbor) could present a greater hazardous situation
to small boats, so physically moving yourself to
higher ground may be the only option.
- Damaging wave activity and unpredictable currents can affect harbors for a period of time following the initial tsunami impact on the coast.
Contact the harbor authority before returning to port
making sure to verify that conditions in the harbor are safe for navigation and berthing. Aonae, Okushiri Island, Japan. Total destruction of houses and other buildings resulting from the tsunami of July 12, 1993, in the Sea of Japan.
Numerous ﬁres broke out following the tsunami adding to the property loss
and misery. Over 120 people were killed by the tsunami in Japan. July 30, 1995 , Chilean Tsunami. Left: An observation of the tsunami
effects behind the breakwater at Tahauku Bay in the Marquesas Islands,
French Polynesia, several thousand kilometers away from the tsunami
source. Right: Currents in Tahauku Bay based on numerical modeling of the Chilean tsunami. The modeling reproduces the same kinds
of ocean currents seen in the photo. 11 Ala Wai Yacht
water caused by
by earthquake of
November 4, 1952,
Russia. The spectators in this picture are needlessly risking their
lives and should
be evacuating to
(Camera Hawaii) s dangerous as tsunamis are, they do not
happen very often. You should not let this
natural hazard diminish your enjoyment of the
beach and ocean. But, if you think a tsunami may be
coming, the ground shakes under your feet or you hear
there is a warning,
tell your relatives
and friends, and A North Shore of
During the tsunami
generated by the
March 9, 1957,
for ﬁsh on the
unaware that tsunami waves would
return in minutes to
inundate the shoreline. (Honolulu StarBulletin) Move
Ground! 12 ACKNOWLEDGMENTS
THE PREPARATION OF THIS BROCHURE WAS SUPPORTED BY:
U.S. Department of Commerce, National Oceanographic and Atmospheric Administration, National Weather Service
UNESCO, Intergovernmental Oceanographic Commission
International Tsunami Information Center
Laboratoire de Geophysique, France
TECHNICAL GUIDANCE PROVIDED BY:
International Tsunami Information Center
Laboratoire de Geophysique, France
U.S. National Weather Service
Richard H. Hagemeyer Pacific Tsunami Warning Center, http://www.prh.noaa.gov/ptwc/
West Coast / Alaska Tsunami Warning Center, http://wcatwc.arh.noaa.gov
U.S. National Ocean Service, http://www.nos.noaa.gov
U.S. National Geophysical Data Center, http://www.ngdc.noaa.gov
U.S. Pacific Marine Environmental Laboratory, http://www.pmel.noaa.gov/pmel
Servicio Hidrografic y Oceanografic, Chile, http://www.shoa.cl
School of Ocean & Earth Science & Technology, University of Hawaii, http://www.soest.hawaii.edu
FURTHER INFORMATION ON THE TSUNAMI WARNING SYSTEM IN THE
PACIFIC, ICG/ITSU, ITIC, AND TSUNAMIS MAY BE OBTAINED FROM:
International Tsunami Information Center
737 Bishop St., Suite 2200, Honolulu, HI 96813 USA
Tel: 808-532-6422, fax: 808-532-5576
EMAIL: [email protected]
UNESCO, Intergovernmental Oceanographic Commission
1, rue Miollis
75732 Paris Cedex 15
EMAIL: [email protected]
Illustrations and Layout by Joe Hunt Design, Honolulu, Hawaii, and ITIC
Background images and wave logo courtesy of Aqualog, France
Revised and Reprinted, May, 2002 ...
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- Spring '08
- Tsunami, International Tsunami Information Center