1. What is a
The phenomenon we call
tsunami is a series of large waves of extremely long wavelength and
period usually generated by a violent, impulsive undersea
disturbance or activity near the coast or in the ocean. When a
sudden displacement of a large volume of water occurs, or if the sea
floor is suddenly raised or dropped by an earthquake, big tsunami
waves can be formed by forces of gravity. The waves travel out of
the area of origin and can be extremely dangerous and damaging when
they reach the shore.
The word tsunami (pronounced
tsoo-nah'-mee) is composed of the Japanese words "tsu" (which
means harbor) and "nami" (which means "wave"). Often the term,
"seismic or tidal sea wave" is used to describe the same phenomenon,
however the terms are misleading, because tsunami waves can be
generated by other, non seismic disturbances such as volcanic
eruptions or underwater landslides, and have physical
characteristics different of tidal waves.
The tsunami waves are completely
unrelated to the astronomical tides – which are caused by the
extraterrestrial, gravitational influences of the moon, sun, and the
planets. Thus, the Japanese word "tsunami", meaning "harbor wave" is
the correct, official and all-inclusive term.
It has been internationally adopted
because it covers all forms of impulsive wave generation.
2. How do
earthquakes generate tsunamis?
By far, the most destructive tsunamis are generated from large,
shallow earthquakes with an epicenter or fault line near or on the
ocean floor. These usually occur in regions of the earth
characterized by tectonic subduction along tectonic plate
boundaries. The high seismicity of such regions is caused by the
collision of tectonic plates. When these plates move past each
other, they cause large earthquakes, which tilt, offset, or displace
large areas of the ocean floor from a few kilometers to as much as a
1,000 km or more.
The sudden vertical displacements over
such large areas, disturb the ocean's surface, displace water, and
generate destructive tsunami waves. The waves can travel great
distances from the source region, spreading destruction along their
path. For example, the Great 1960 Chilean tsunami was generated by a
magnitude 8.3 earthquake that had a rupture zone of over 1,000 km.
Its waves were destructive not only in
Chile, but also as far away as Hawaii, Japan and elsewhere in the
Pacific. It should be noted that not all earthquakes generate
Usually, it takes an earthquake with a
Richter magnitude exceeding 7.5 to produce a destructive tsunami.
3. How do
volcanic eruptions generate tsunamis?
Although relatively infrequent, violent volcanic eruptions represent
also impulsive disturbances, which can displace a great volume of
water and generate extremely destructive tsunami waves in the
immediate source area. According to this mechanism, waves may be
generated by the sudden displacement of water caused by a volcanic
explosion, by a volcano's slope failure, or more likely by a
phreatomagmatic explosion and collapse/engulfment of the volcanic
One of the largest and most destructive
tsunamis ever recorded was generated in August 26, 1883 after the
explosion and collapse of the volcano of Krakatoa (Krakatau), in
Indonesia. This explosion generated waves that reached 135 feet,
destroyed coastal towns and villages along the Sunda Strait in both
the islands of Java and Sumatra, killing 36, 417 people.
It is also believed that the destruction
of the Minoan civilization in Greece was caused in 1490 B.C. by the
explosion/collapse of the volcano of Santorin in the Aegean Sea.
4. How do
submarine landslides, rock falls and underwater slumps generate
Less frequently, tsunami waves can be generated from displacements
of water resulting from rock falls, icefalls and sudden submarine
landslides or slumps. Such events may be caused impulsively from the
instability and sudden failure of submarine slopes, which are
sometimes triggered by the ground motions of a strong earthquake.
For example in the 1980's, earth moving
and construction work of an airport runway along the coast of
Southern France, triggered an underwater landslide, which generated
destructive tsunami waves in the harbor of Thebes. Major earthquakes
are suspected to cause many underwater landslides, which may
contribute significantly to tsunami generation. For example, many
scientists believe that the 1998 tsunami, which killed thousands of
people and destroyed coastal villages along the northern coast of
Papua-New Guinea, was generated by a large underwater slump of
sediments, triggered by an earthquake.
In general, the energy of tsunami waves generated from landslides or
rock falls is rapidly dissipated as they travel away from the source
and across the ocean, or within an enclosed or semi-enclosed body of
water – such as a lake or a fjord. However, it should be noted, that
the largest tsunami wave ever observed anywhere in the world was
caused by a rock fall in Lituya Bay, Alaska on July 9, 1958.
Triggered by an earthquake along the
Fairweather fault, an approximately 40 million cubic meter rock fall
at the head of the bay generated a wave, which reached the
incredible height of 520-meter wave (1,720 feet) on the opposite
side of the inlet. A initial huge solitary wave of about 180 meters
(600 feet) raced at about 160 kilometers per hour (100 mph) within
the bay debarking trees along its path.
However, the tsunami's energy and height
diminished rapidly away from the source area and, once in the open
ocean, it was hardly recorded by tide gauge stations.
asteroids, meteorites or man-made explosions cause tsunamis?
Fortunately, for mankind, it is indeed very rare for a meteorite or
an asteroid to reach the earth. No asteroid has fallen on the earth
within recorded history. Most meteorites burn as they reach the
earth's atmosphere. However, large meteorites have hit the earth's
surface in the distant past. This is indicated by large craters,
which have been found in different parts of the earth.
Also, it is possible that an asteroid
may have fallen on the earth in prehistoric times – the last one
some 65 million years ago during the Cretaceous period. Since
evidence of the fall of meteorites and asteroids on earth exists, we
must conclude that they have fallen also in the oceans and seas of
the earth, particularly since four fifths of our planet is covered
The fall of meteorites or asteroids in the earth's oceans has the
potential of generating tsunamis of cataclysmic proportions.
Scientists studying this possibility have concluded that the impact
of moderately large asteroid, 5-6 km in diameter, in the middle of
the large ocean basin such as the Atlantic Ocean, would produce a
tsunami that would travel all the way to the Appalachian Mountains
in the upper two-thirds of the United States. On both sides of the
Atlantic, coastal cities would be washed out by such a tsunami.
An asteroid 5-6 kilometers in diameter
impacting between the Hawaiian Islands and the West Coast of North
America, would produce a tsunami which would wash out the coastal
cities on the West coasts of Canada, U.S. and Mexico and would cover
most of the inhabited coastal areas of the Hawaiian islands.
Conceivably tsunami waves can also be generated from very large
nuclear explosions. However, no tsunami of any significance has ever
resulted from the testing of nuclear weapons in the past.
Furthermore, such testing is presently
prohibited by international treaty.
6. Where and
how frequently are tsunamis generated?
Tsunamis are disasters that can be generated in all of the world's
oceans, inland seas, and in any large body of water. Each region of
the world appears to have its own cycle of frequency and pattern in
generating tsunamis that range in size from small to the large and
highly destructive events. Most tsunamis occur in the Pacific Ocean
and its marginal seas.
The reason is that the Pacific covers
more than one-third of the earth's surface and is surrounded by a
series of mountain chains, deep-ocean trenches and island arcs
called the "ring of fire" – where most earthquakes occur (off the
coasts of Kamchatka, Japan, the Kuril Islands, Alaska and South
Many tsunamis have also been generated
in the seas which border the Pacific Ocean.
Tsunamis are generated, by shallow earthquakes all around the
Pacific, but those from earthquakes in the tropical Pacific tend to
be modest in size. While such tsunamis in these areas may be
devastating locally, their energy decays rapidly with distance.
Usually, they are not destructive a few hundred kilometers away from
their sources. That is not the case with tsunamis generated by great
earthquakes in the North Pacific or along the Pacific coast of South
America. On the average of about half-a-dozen times per century, a
tsunami from one of these regions sweeps across the entire Pacific,
is reflected from distant shores, and sets the entire ocean in
motion for days.
For example, the 1960 Chilean tsunami
caused death and destruction throughout the Pacific. Hawaii, Samoa,
and Easter Island all recorded runups exceeding 4 m; 61 people were
killed in Hawaii. In Japan 200 people died. A similar tsunami in
1868 from northern Chile caused extensive damage in the Austral
Islands, Hawaii, Samoa and New Zealand.
Although not as frequent, destructive
tsunamis have been also been generated in the Atlantic and the
Indian Oceans, the Mediterranean Sea and even within smaller bodies
of water, like the Sea of Marmara, in Turkey. In 1999, a large
earthquake along the North Anatolian Fault zone, generated a local
tsunami, which was particularly damaging in the Bay of Izmit.
In the last decade alone, destructive
tsunamis have occurred in Nicaragua (1992), Indonesia (1992, 1994,
1996), Japan (1993), Philippines (1994), Mexico (1995), Peru (1996,
2001), Papua-New Guinea (1998), Turkey (1999), and Vanuatu (1999).
7. How does
tsunami energy travel across the ocean and how far can tsunamis
Once a tsunami has been generated, its energy is distributed
throughout the water column, regardless of the ocean's depth. A
tsunami is made up of a series of very long waves. The waves will
travel outward on the surface of the ocean in all directions away
from the source area, much like the ripples caused by throwing a
rock into a pond.
The wavelength of the tsunami waves and
their period will depend on the generating mechanism and the
dimensions of the source event. If the tsunami is generated from a
large earthquake over a large area, its initial wavelength and
period will be greater. If the tsunami is caused by a local
landslide, both its initial wavelength and period will be shorter.
The period of the tsunami waves may range from 5 to 90 minutes. The
wave crests of a tsunami can be a thousand km long, and from a few
to a hundred kilometers or more apart as they travel across the
On the open ocean, the wavelength of a
tsunami may be as much as two hundred kilometers, many times greater
than the ocean depth, which is on the order of a few kilometers. In
the deep ocean, the height of the tsunami from trough to crest may
be only a few centimeters to a meter or more – again depending on
the generating source.
Tsunami waves in the deep ocean can travel at high speeds for long
periods of time for distances of thousands of kilometers and lose
very little energy in the process. The deeper the water, the greater
the speed of tsunami waves will be. For example, at the deepest
ocean depths the tsunami wave speed will be as much as 800 km/hr,
about the same as that of a jet aircraft. Since the average depth of
the Pacific ocean is 4000 m (14,000 feet), tsunami wave speed will
average about 200 m/s or over 700 km/hr (500 mph).
At such high speeds, a tsunami generated
in Aleutian Islands may reach Hawaii in less than four and a half
In 1960, great tsunami waves generated
in Chile reached Japan, more than 16,800 km away in less than 24
hours, killing hundreds of people.
8. Why aren't
tsunamis seen at sea or from the air?
In the deep ocean, tsunami wave amplitude is usually less than 1 m
(3.3 feet). The crests of tsunami waves may be more than a hundred
kilometers or more away from each other. Therefore, passengers on
boats at sea, far away from shore where the water is deep, will not
feel nor see the tsunami waves as they pass by underneath at high
speeds. The tsunami may be perceived as nothing more than a gentle
rise and fall of the sea surface.
The Great Sanriku tsunami, which struck
Honshu, Japan, on June 15, 1896, was completely undetected by
fishermen twenty miles out to sea. The deep-water height of this
tsunami was only about 40 centimeters when it passed them and yet,
when it arrived on the shore, it had transformed into huge waves
that killed 28,000 people, destroyed the port of Sanriku and
villages along 275 km of coastline. For the same reason of low
amplitude and very long periods in the deep ocean, tsunami waves
cannot be seen nor detected from the air.
From the sky, tsunami waves cannot be
distinguished from ordinary ocean waves.
9. What are
the factors of destruction from tsunamis?
There are three: inundation, wave impact on structures, and erosion.
Strong, tsunami-induced currents lead to the erosion of foundations
and the collapse of bridges and seawalls. Flotation and drag forces
move houses and overturn railroad cars.
Considerable damage is caused by the
resultant floating debris, including boats and cars that become
dangerous projectiles that may crash into buildings, break power
lines, and may start fires. Fires from damaged ships in ports or
from ruptured coastal oil storage tanks and refinery facilities, can
cause damage greater than that inflicted directly by the tsunami.
Of increasing concern is the potential
effect of tsunami draw down, when receding waters uncover cooling
water intakes of nuclear power plants.
determines how destructive a tsunami will be near the origin and at
a distant shore?
Tsunamis arrive at a coastline as a series of successive crests
(high water levels) and troughs (low water levels) – usually
occurring 10 to 45 minutes apart. As they enter the shallow waters
of coastlines, bays, or harbors, their speed decreases to about
50-60 km/hr. For example, in 15 m of water the speed of a tsunami
will be only 45 km/hr. However 100 or more kilometers away, another
tsunami wave travels in deep water towards the same shore at a much
greater speed, and still behind it there is another wave, traveling
at even greater speed.
As the tsunami waves become compressed
near the coast, the wavelength is shortened and the wave energy is
directed upward – thus increasing their heights considerably. Just
as with ordinary surf, the energy of the tsunami waves must be
contained in a smaller volume of water, so the waves grow in height.
Even though the wavelength shortens near the coast, a tsunami will
typically have a wavelength in excess of ten kilometers when it
comes ashore. Depending on the water depth and the coastal
configuration, the waves may undergo extensive refraction – another
process that may converge their energy to particular areas on the
shore and thus increase the heights even more.
Even if a tsunami wave may have been 1
meter of less in the deep ocean, it may grow into a huge 30-35 meter
wave when it sweeps over the shore. Thus, tsunami waves may smash
into the shore like a wall of water or move in as a fast moving
flood or tide – carrying everything on their path. Either way, the
waves become a significant threat to life and property. If the
tsunami waves arrive at high tide, or if there are concurrent storm
waves in the area, the effects will be cumulative and the inundation
and destruction even greater.
The historic record shows that there
have been many tsunamis that have struck the shores with devastating
force, sometimes reaching heights of more than 30-50 meters. For
example, the 1946 tsunami generated by an earthquake off Unimak
island in Alaska's Aleutian Islands, reached heights of more than 35
meters, which destroyed a reinforced concrete lighthouse and killed
Finally, the maximum height a tsunami reaches on shore is called the
runup. It is the vertical distance between the maximum height
reached by the water on shore and the mean sea level surface. Any
tsunami runup over a meter is dangerous. The flooding by individual
waves will typically last from ten minutes to a half-hour, so the
danger period can last for hours. Tsunami runup at the point of
impact will depend on how the energy is focused, the travel path of
the tsunami waves, the coastal configuration, and the offshore
Small islands with steep slopes usually
experience little runup – wave heights there are only slightly
greater than on the open ocean. This is the reason that islands with
steep-sided fringing or barrier reefs are only at moderate risk from
tsunamis. However, this is not the case for islands such as the
Hawaiian or the Marquesas. Both of these island chains do not have
extensive barrier reefs and have broad bays exposed to the open
For example, Hilo Bay at the island of
Hawaii and Tahauku Bay at Hiva Oa in the Marquesas are especially
vulnerable. The 1946 Aleutian tsunami resulted in runup, which
exceeded 8 m at Hilo and 10 m at Tahauku; 59 people were killed in
Hilo and two in Tahauku. Similarly, any gap in a reef puts the
adjacent shoreline at risk. The local tsunami from the Suva
earthquake of 1953 did little damage because of Fiji's extensive
However, two villages on the island of
Viti Levu, located on opposite gaps in the reef, were extensively
damaged and five people were drowned.
11. What are
some of the largest historical tsunamis?
Destructive tsunamis have occurred in all of the world's oceans and
seas. In the last half of the 20th Century, Pacific-wide,
destructive tsunamis occurred in 1946, 1952, 1957, 1960, and 1964.
(Many more tsunamis in inland seas around the periphery of the
Pacific, where extremely destructive locally and claimed thousands
Such localized tsunamis occurred in
1975, 1983, 1985, 1992, 1993, 1995, 1998, 1999 and 2001.
The 1 April 1946 Aleutian Earthquake and
One of the most destructive Pacific-wide tsunamis was generated
by a magnitude 7.8 earthquake near Unimak Island in Alaska's
Aleutian Island Chain. A huge wave of 35 meters destroyed
completely the U.S. Coast Guard's Scotch Cap lighthouse on
Unimak and killed all five of its occupants.
The lighthouse was a
steel-reinforced concrete structure standing about 30 meters
above sea level. Without warning, destructive tsunami waves
reached the Hawaiian Islands, five hours later, causing
considerable damage and loss of life. The waves completely
obliterated Hilo's waterfront on the island of Hawaii, killing
159 people there. Altogether a total 165 people lost their lives
from this tsunami, including children attending school at
Hawaii's Laupahoehoe Point, where waves reaching up to 8 m
destroyed also a hospital. Damage was estimated at $26 million
(in 1946 dollars).
In 1948, and as a result of this
tsunami, the U.S. established a Pacific Tsunami Warning Center
The 4 November 1952 Kamchatka
Earthquake and Tsunami
A strong earthquake (magnitude 8.2) off the coast of Kamchatka
Peninsula generated a great destructive Pacific-wide tsunami.
Its waves struck the Kamchatka Peninsula, the Kuril Islands and
other areas of Russia's Far East, causing considerable damage
and loss of life. The tsunami was widely observed and recorded
in Japan, but there was no loss of life or damage there.
There was considerable damage in the
Hawaiian Islands and some damage in Peru and Chile. The tsunami
was recorded or observed throughout the islands of the Pacific.
In New Zealand waves reached height of 1m. In Alaska, in the
Aleutian Islands and in California waves of up to 1.4 meters
were observed or recorded.
By far the largest waves outside the generating area were
observed in the Hawaiian Islands. Fortunately, no human lives
were lost in Hawaii from this tsunami, but damage was extensive,
estimates ranging from $800,000- $1,000,000 (in 1952 dollars).
The tsunami caused damage on Midway Island. Elsewhere in the
Hawaiian island chain, the waves destroyed boats and piers,
knocked down telephone lines, and caused extensive beach
erosion. In some locations, tsunami waves were destructive in
certain locations but hardly noticeable at others.
The north shore of the Island of
Oahu experienced higher waves of up to 4.5 meters. On the south
shore of the island, the tsunami was powerful enough to throw a
cement barge in the Honolulu Harbor into a freighter. The island
of Hawaii experienced run up to 6.1 meters. In Hilo, a small
bridge connecting Coconut Island to the shore was destroyed by
one of the tsunami waves lifting it off its foundation, then
smashing it down. The effects of the tsunami in the generating
area in Kamchatka, varied significantly.
From Kamchatka Peninsula to
Kronotsky Peninsula the wave heights ranged from zero to 5
meters. From Kronotsky Peninsula to Cape Shipursky the heights
ranged from 4-13 meters. The highest wave of 13 meters was the
third and was observed at Olga Bay, where it caused considerable
damage. Travel time of the first tsunami wave to Olga Bay was
approximately 42 minutes after the earthquake. From Cape
Shipursky to Cape Povorotny, the tsunami waves ranged from 1 to
10 meters and caused considerable loss of life and damage.
At Avachinskaia Bay the tsunami
height was 1.2 meters and its travel time was about 30 minutes.
From Cape Povorotny to Cape Lopatkka the waves ranged from 5 to
15 meters. At Khodutka Bay a cutter was thrown 500 meters back
from shore. On the West coast of Kamchatka Peninsula, the
maximum tsunami runup at Ozernoe was 5 meters. At Alaid Island
of the Kuril Island group, run up was 1.5 meters. At Shumshu
Island it ranged from 7-9 meters. At Paramushir Island the waves
ranged from 4-18.4 meters.
At Severo – Kurilsk on Paramushir
Island, the second wave was the highest reaching maximum run up
of 15 meters. It destroyed most of the town and caused
considerable loss of life. At Onekotan Island tsunami run up was
9 meters, while at Shiashkoton Island it was 8 meters and at
Iturup Island 2.5 meters. Waves of up to 2 meters were observed
at the Komandorsk Islands and at Okhotsk.
At Sakhalin – Korsakov a 1-meter
tsunami wave was observed.
The 9 March 1957 Aleutian
Earthquake and Tsunami
On March 9, 1957, an 8.3 magnitude earthquake south of the
Andreanof Islands, in the Aleutian Islands of Alaska – in the
same general area as that of April 1, 1946 – generated a
Pacific-wide tsunami. Although no lives were lost, there was
extensive destruction of property in the Hawaiian Islands, with
damage estimated at approximately $5 million (1957 dollars).
The waves were particularly high on
the north shore of the island of Kauai where they reached a
maximum height of 16 meters, flooding the highway and destroying
houses and bridges. This was twice the height of the 1946
tsunami. At Hilo, Hawaii, the tsunami runup reached 3.9 m and
there was damage to numerous buildings along the waterfront.
Within Hilo Bay, Coconut Island was
covered by 1 m of water and the bridge connecting it to the
shore, as in 1952, was again destroyed.
The 22 May 1960 Chilean Earthquake
The largest earthquake ( magnitude 8.6) of the 20th century
occurred on May 22, 1960 off the coast of south central Chile.
It generated a Pacific-wide tsunami, which was destructive
locally in Chile and throughout the Pacific Ocean.
The tsunami killed an estimated
2,300 people in Chile. There was tremendous loss of life and
property in the Hawaiian Islands, in Japan and elsewhere in the
Pacific. Destructive waves in Hilo, Hawaii, destroyed the
waterfront and killed 61 people.
Total damage was estimated at more
than $500 million (1960 dollars).
The 28 March 1964 Alaska Earthquake
The largest earthquake of the 20th Century in the northern
hemisphere, with a magnitude 8.4, affected an area in Alaska
that was almost 1600 km long and more than 300 km wide –
extending from Valdez to the Trinity Islands, southwest of
Kodiak Island in the Gulf of Alaska. The earthquake caused areas
to be lifted by as much as 15 m (50 feet) in certain areas,
while many other areas subsided greatly.
In addition to many local tsunamis
generated within the Prince William Sound, vertical crustal
displacements averaging 1.8 m (6 ft.) over an area of about
300,000 square kilometers (115,000 square miles) extending in
the Gulf of Alaska's continental shelf, generated a Pacific-wide
tsunami. Its waves were very destructive in southeastern Alaska,
in Vancouver Island (British Columbia), and in the U.S. States
of Washington, California and Hawaii.
The tsunami killed more than 120
people and caused more than $106 million in damages, making it
the costliest ever to strike the Western United States and
Canada. Five of Alaska's seven largest communities were
devastated by the combination of earthquake and tsunami wave
damage. Alaska's fishing industry and most seaport facilities
were virtually destroyed. Tsunami waves at Kodiak Island washed
away a total of 158 houses and buildings within two blocks of
Fishing boats were carried hundreds
of meters inland. The 1964 tsunami waves caused also extensive
damage in Vancouver Island (British Columbia), and in the states
of Washington, California and Hawaii, in the United States. The
waves affected the entire California coastline, but were
particularly high from Crescent City to Monterey ranging from
2.1 - 6.3 meters (7-21 feet). Hardest hit was Crescent City,
California, where waves reaching as much as 6 meters (20-21
feet) destroyed half of the waterfront business district.
Eleven persons lost their lives
there. At Santa Cruz Harbor, the tsunami waves reached as high
as 3.3 meters (11 feet) causing some damage. There was extensive
damage in San Francisco Bay, the marinas in Marin County and at
the Noyo, Los Angeles and Long Beach harbors.
Estimated losses in California were
between $1,500,000 and $2,375,000 (1964 dollars), while at
Crescent City tsunami damage was estimated at $7,414,000.
12. Why are locally
generated tsunamis so dangerous?
A locally generated tsunami may reach a nearby shore in less than
ten minutes. There is not sufficient time for the Pacific Tsunami
Warning Center or for local authorities to issue a warning. For
people living near the coast, the shaking of the ground is a warning
that a tsunami may be imminent.
For tsunamis from more distant sources,
however, accurate warnings of when a tsunami might arrive are
possible because tsunamis travel at a known speed.
13. Where can
I find more tsunami related FAQs?
Geoscience Australia's Tsunami Factsheet
- These questions are answered on this factsheet:
What is a tsunami?
How do tsunamis occur?
Do tsunamis reach Australia?
How are tsunami warnings issued?
Oahu Civil Defense Agency
Tsunami Questions and Answers
- These questions are answered by the Oahu Civil Defense Agency:
What is a tsunami?
What areas of Oahu are
vulnerable to tsunamis?
How will I know that a tsunami
What should I do when watches,
warning or tsunami evacuation advisories/orders are issued?
How can I get to a safe area or
shelter if I have no transportation?
Will residents and property
owners be allowed to enter tsunami evacuation zones?
What if a tsunami warning is
issued while my child is in school?
How can I obtain emergency
How can I obtain more
information about tsunami hazards and preparedness?
Pacific Tsunami Museum FAQs
- These questions are answered on the Pacific Tsunami Museum
Where is Hilo, Hawaii?
What does the word tsunami mean?
What causes a tsunami?
How is a tsunami wave different
from a normal wave?
What is run-up?
Do all oceans have tsunamis?
How are tsunami wave heights
How long does it take a tsunami
to reach land?
What is the Tsunami Warning
What is the difference between a
Tsunami Watch and a Tsunami Warning?
How many warnings have been
issued by the Pacific Tsunami Warning Center since it was
What should I do or not do in a
Can the arrival time of a
tsunami be accurately predicted?
What has been the most
destructive tsunami to strike the Hawaiian Islands in recent
How many Pacific-wide tsunamis
have struck the Hawaiian Islands in recent history?
How many locally generated
tsunamis have occurred in the Hawaiian Islands in recent
What is the "wrap-around"
How many waves are there in a
How does a tsunami behave as it
How are inundation/evacuation
Since I don't live in an
inundation area why should I be concerned?
If I would like more information
on tsunamis who should I contact?
PMEL's Tsunami: FAQs
- At this site you can find questions answered by PMEL tsunami
West Coast/Alaska Tsunami Warning Center FAQs
http://wcatwc.arh.noaa.gov/frequently.htm - Questions
What does the West Coast and
Alaska Tsunami Warning Center do?
When is a warning issued?
If you feel a large earthquake,
should you wait for a warning or evacuate?
How are tsunami generated?
Do all large earthquakes,
greater than magnitude 7.0 generate dangerous tsunamis?
What was the biggest earthquake
Does Alaska have a history as a
dangerous tsunami source region?
What does the word 'tsunami'
Can a tsunami sink a ship?
TsuInfo Alert Newsletter
And in case your question falls within the range of "Infrequently"
Asked Questions, try looking at the online issues of TsuInfo Alert
Newsletter. Each issue usually has a column of questions compiled by
Lee Walkling of Washington's Division of Geology and Earth Resources
Example question: If you hiked Mt. St.
Helens, could you find evidence of a tsunami?
14. What is a
mega-tsunami and can it happen today?
The following is a position paper that was issued by the Tsunami
Society concerning the occurrence of Mega-Tsunamis:
The mission of the Tsunami Society
includes "the dissemination of knowledge about tsunamis to
scientists, officials, and the public". We have established a
committee of private, university, and government scientists to
accomplish part of this goal by correcting misleading or invalid
information released to public about this hazard.
We can supply both valid, correct
and important information and advice to the public, and the
names of reputable scientists active in the field of tsunami,
who can provide such information.
Most recently, the Discovery Channel has replayed a program
alleging potential destruction of coastal areas of the Atlantic
by tsunami waves which might be generated in the near future by
a volcanic collapse in the Canary Islands. Other reports have
involved a smaller but similar catastrophe from Kilauea volcano
on the island of Hawaii.
They like to call these occurrences
"mega tsunamis". We would like to halt the scaremongering from
these unfounded reports. We wish to provide the media with
factual information so that the public can be properly informed
about actual hazards of tsunamis and their mitigation.
Here are a set of facts, agreed on by
committee members, about the claims in these reports:
While the active volcano of Cumbre
Vieja on Las Palmas is expected to erupt again, it will not send
a large part of the island into the ocean, though small
landslides may occur. The Discovery program does not bring out
in the interviews that such volcanic collapses are extremely
rare events, separated in geologic time by thousands or even
millions of years.
No such event – a mega tsunami – has
occurred in either the Atlantic or Pacific oceans in recorded
The colossal collapses of Krakatau
or Santorin (the two most similar known happenings) generated
catastrophic waves in the immediate area but hazardous waves did
not propagate to distant shores. Carefully performed numerical
and experimental model experiments on such events and of the
postulated Las Palma event verify that the relatively short
waves from these small, though intense, occurrences do not
travel as do tsunami waves from a major earthquake.
The U.S. volcano observatory,
situated on Kilauea, near the current eruption, states that
there is no likelihood of that part of the island breaking off
into the ocean.
These considerations have been
published in journals and discussed at conferences sponsored by
the Tsunami Society.
Some papers on this subject include:
"Evaluation of the threat of Mega
Tsunami Generation From ....Volcanoes on La Palma ... and
Hawaii", George Pararas-Carayannis, in Science of Tsunami
Hazards, Vol 20, No.5, pages 251-277, 2002.
"Modeling the La Palma Landslide
Tsunami", Charles L. Mader, in Science of Tsunami Hazards, Vol.
19, No. 3, pages 160-180, 2001.
"Volcano Growth and the Evolution of
the Island of Hawaii", J.G. Moore and D.A.Clague, in the
Geologic Society of America Bulletin, 104, 1992.
Committee members for this report
include (all can comment on this or other tsunami matters):
Mr. George Curtis, Hilo, HI
(Committee Chairman) 808-963-6670
Dr. Tad Murty, Ottawa, Canada,
Dr. Laura Kong, Honolulu, HI,
Dr. George Pararas-Carayannis,
Honolulu, HI, 808-943-1150
Dr. Charles L. Mader, Los Alamos,
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