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Keywords searched: 16

  1. What is a tsunami?
  2. What year was the first tsunami recorded? (I have found more than one answer to this.)
  3. What is the worst tsunami to ever hit the United States (including Hawaii and Alaska)?
  4. Crumbling Volcano Threatens Atlantic, Caribbean Coastlines
  5. How do landslides, volcanic eruptions and cosmic collisions generate tsunamis?
  6. Where can I find information about historical tsunamis, including their frequency and location?
  7. What are tsunamis?
  8. What causes tsunamis?
  9. Where are tsunamis most common?
  10. Can a tsunami be prevented?
  11. What is the worst part of a tsunami?
  12. How can someone tell when a tsunami is coming?
  13. What was the biggest tsunami? What was the outcome?
  14. How did you get interested in studying tsunamis?
  15. What is a person supposed to do when a tsunami comes?

  1. What is a tsunami?

    A tsunami (pronounced soo-nah-mee) is a series of waves of extremely long wave length and long period generated in a body of water by an impulsive disturbance that vertically displaces the water.

    The term tsunami was adopted for general use in 1963 by an international scientific conference. Tsunami is a Japanese word represented by two characters: "tsu" and "nami." The character "tsu" means harbor, and the character "nami" means wave. In the past, tsunamis were often referred to as "tidal waves." The term "tidal wave" is a misnomer. Tides are the result of gravitational influences of the moon, sun, and planets. Tsunamis are not caused by the tides and are unrelated to the tides; although a tsunami striking a coastal area is influenced by the tide level at the time of impact. See The Tsunami Story and the NOAA Tsunami Basics for for detailed explanations.

    More information can be found at The WC/ATWC page on Physics of Tsunamis , the FEMA Tsunami Fact sheet , Tsunami the Great Waves.

    Authority: NOAA Center for Tsunami Research

  2. What year was the first tsunami recorded? (I have found more than one answer to this.)

    There is geological evidence that large tsunamis have occurred thousands of years ago. In terms of the earliest tsunami in the historical record, a volcano erupted on Santorini Island, Greece and created a large tsunami. The years I've found for this event are 1628 BC and 1410 BC. This tsunami is thought to have so large that it destroyed an entire civilization. The Chinese and Japanese have a long history of recording tsunamis, but I didn't find any dates for the earliest ones of these.

    Authority: Dr. Hal Mofjeld, interview in February 25, 2005, NOAA Center for Tsunami Research

  3. What is the worst tsunami to ever hit the United States (including Hawaii and Alaska)?

    Including Hawaii and Alaska, the worst tsunami to strike the United States was the 1946 Alaska tsunami that killed 165 people (almost all of these in Alaska and Hawaii).

    Authority: Dr. Hal Mofjeld, interview in February 25, 2005, NOAA Center for Tsunami Research

  4. Crumbling Volcano Threatens Atlantic, Caribbean Coastlines

    Scientists from University College London issued warnings that the flank of a volcanic island in the eastern Atlantic is at risk of collapsing and generating a wave up to 160 feet high that could swamp the coastlines of the Caribbean and eastern Florida.

    Simon Day of the college's Hazard Research Center wrote in New Scientist that a huge chunk of La Palma, the most volcanically active island in the Canaries, is now unstable. "If the flank of the volcano slides into the ocean, the mass of moving rock will push the water in front of it, creating a tsunami wave far larger than any seen in history," said Day. "The wave would then spread out across the Atlantic at the speed of a jet airliner until it strikes coastal areas all around the North Atlantic."

    Day identified scores of volcanic vents in the 7,957-foot-high Cumbre Vieja Volcano that comprises the southern half of the island of La Palma. He determined that the western flank of the mountain, a mass of approximately 500 billion tons of rock, is slowly detaching itself as volcanic activity forces magma to the top of the volcano. A major volcanic explosion could cause the flank to detach and fall into the sea with catastrophic effects.

    Simon Day - (s.day@ucl.ac.uk)
    The Benfield Hazard Research Centre,
    Research School of Geological and Geophysical Sciences
    University College London
    -- Currently (2005.01.03) --
    Visiting associate researcher at University of California Santa Cruz.
    Tel +1-831-459-5143
    Fax +1-831-459-3074
    Email sday@es.ucsc.edu

    For more information about Atlantic tsunamis please contact:
    Paula Dunbar,
    NOAA, National Geophysical Data Center, E/GC2
    325 BROADWAY
    BOULDER, CO 80305-3328
    PH: (303)497-6084
    FAX:(303)497-6513
    Internet Address: paula.dunbar@noaa.gov



    Authority: NOAA Center for Tsunami Research

  5. How do landslides, volcanic eruptions and cosmic collisions generate tsunamis?

    Any disturbance that displaces a large water mass from its equilibrium position can generate a tsunami. Generally tsunamis caused by landslides or volcanic eruptions dissipate more quickly than Pacific-wide tsunamis caused by some earthquakes and rarely affect coastlines distant from the source. See also: Tsunami the Great Waves

    Authority: NOAA Center for Tsunami Research

  6. Where can I find information about historical tsunamis, including their frequency and location?

    The National Geophysical Data Center maintains a historical tsunami event and runup database. We have been reviewing and quality-controlling the records in the database over the past 5-6 years. It is an ongoing project but most of the data have been verified. The data are available online via text forms and arcims maps. I have listed the URLs below. Let me know if you have questions.


    Authority: Paula Dunbar, NGDC, NOAA Center for Tsunami Research

  7. What are tsunamis?

    Tsunamis (pronounced soo-nah-mee) are a series of long period shallow water waves that are generated by the sudden displacement of water due to subsea, or underwater, disturbances such as earthquakes, submarine landslides, or volcanic eruptions. Less commonly, a meteor impact to the ocean or meteorological forcing can generate a tsunami. The first wave may not be the largest and successive waves may be spaced many minutes apart and continue to arrive at a coastline for several hours.

    The word tsunami is Japanese and comes from the Japanese character "tsu" meaning harbor, and the character "nami" meaning wave. Many people confuse the “harbor wave” translation as meaning “tidal wave” but this is not correct because tsunamis are caused by unpredictable motion of the earth while tides occur predictably from the gravitational influences of the moon, sun, and planets.

    Authority: NOAA Center for Tsunami Research

  8. What causes tsunamis?

    Tsunamis are most often caused by earthquakes and landslides. These natural events push the water upward, sideways or downward to generate the tsunami waves. Volcanic eruptions can also cause tsunamis. There is evidence that in the distant past, asteroids and comets striking the Earth created enormous tsunamis. In the case of an earthquake, the most common way tsunamis are generated, a portion of the seafloor is moved relative to another portion that is not moved. In other words, certain types of earthquakes cause the seafloor to drop or raise in some places. The drop causes the water above it to also drop which sets up a wave. Not all earthquakes generate tsunamis, and not all tsunamis are generated from earthquakes. For instance, submarine landslides may also generate a tsunami.

    Authority: NOAA Center for Tsunami Research

  9. Where are tsunamis most common?

    Tsunamis are most common in the Pacific Ocean Basin. The entire Pacific Ocean is ringed by areas known as subduction zones, where the tectonic plates of the earth are moving relative to one another. Subduction zones are where two or more plates are colliding and one is going underneath another. This is where there are ocean trenches. There are a lot of earthquakes daily around the Pacific in these regions, which is why the coastal areas around the Pacific is called the Ring of Fire.

    Authority: NOAA Center for Tsunami Research

  10. Can a tsunami be prevented?

    No, there is no way to prevent a tsunami because there is no way to stop the earth’s plates from moving and causing earthquakes.

    Authority: NOAA Center for Tsunami Research

  11. What is the worst part of a tsunami?

    Most people would say that the worst part of a tsunami is the flooding when it hits land or the impact it has on people’s lives. If the tsunami waves are large, the water destroys what is in its path. People who do not get to high ground fast enough can either drown or be killed by any of the large objects that are being carried by the waves.

    Authority: NOAA Center for Tsunami Research

  12. How can someone tell when a tsunami is coming?

    Some earthquakes generate tsunamis and some don’t. If a tsunami is generated far away from where a person is, models and local emergency officials will probably notify the people who are in danger. If the tsunami is generated close to where a person is, they will probably feel the earthquake and even though they might not know for sure right away, they should know that a tsunami is possible and run to high ground immediately. If there is no one to tell a person on the coast about a tsunami coming or if a tsunami is generated close by, the water might let the person know. Tsunamis are waves with a high part (crest) of each wave and a low part of each wave (trough). Frequently the low part of tsunami waves arrive first so a person would see a draw down or what looks to be a very low tide. A person seeing this should think a tsunami is coming and run to high ground. So, water going out further than ever seen before is a sign that a tsunami is coming.

    Authority: NOAA Center for Tsunami Research

  13. What was the biggest tsunami? What was the outcome?

    The highest, reliably measured tsunami on record occurred in Lituya Bay, Alaska on 9 July 1958. This was an uncommon event caused by a landslide when a very large area of material from a slope above the Bay broke away and fell abruptly into the Bay. The resulting tsunami washed up the slope on the opposite side of the narrow bay to a height of 518 m (1,700 ft). It is believed by some scientists that larger tsunamis have occurred from asteroids or meteors falling into the ocean in the geologic past.

    The Lituya Bay tsunami was not generated by an earthquake and it was contained within the Bay so it didn't travel across the Pacific Ocean. The outcome of this tsunami was the death of 3 people and deforestation of Lituya Bay slopes.

    Authority: NOAA Center for Tsunami Research

  14. How did you get interested in studying tsunamis?

    My interest in tsunamis developed really quite accidentally. I was always interested in math and physics so when I was in college I looked at options to apply these subjects to real world phenomena. I learned about ocean tides, currents, and internal waves in some of the oceanography courses I took and decided to study the physics of the ocean in graduate school. After graduate school I worked for a consulting company modeling currents and then took a job with the tsunami group at the NOAA Pacific Marine Environmental Laboratory. Tsunamis are particularly interesting and rewarding to study because there is an opportunity to have a real affect on the lives of people that might some day be impacted by a tsunami.

    Authority: NOAA Center for Tsunami Research

  15. What is a person supposed to do when a tsunami comes?

    People in danger from a tsunami should run to high ground immediately. Many people have died thinking they can out run a tsunami but no one really can.

    Authority: NOAA Center for Tsunami Research