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Keywords searched: 8

  1. What is the mathematical formula for the speed of a tsunami?
  2. What was the highest tsunami?
  3. Does a tsunami affect the weather?
  4. What is the current tool used to detect tsunamis?
  5. Is it possible for a tsunami to hit the East Coast? Has it ever happened?
  6. Are tsunamis measured on a scale similar to those of tornadoes and hurricanes?
  7. Do tsunamis lose speed as they approach land?
  8. What type of force is needed to allow a tsunami to travel a long distance?
  9. Could the effects of atomic bombs tested in the Pacific enhance force of waves and tsunamis?
  10. How do you think the new warnings systems will help people in Hawaii, California, Oregon, Washington, and Alaska be better prepared for tsunamis?
  11. What was the reason you started doing research on tsunami patterns? What do you hope to accomplish with this tsunami research and how long will it take? How far do you think you are from your goal?
  12. Are tsunamis more (or less) dangerous on islands or on normal coasts? Is Hawaii hit so often because it's an island or because it's "in the way" of most tsunamis in the Pacific?
  13. Why does the amplitude of the wave rise when the tsunami reaches a beach?
  14. Was the Bourbon tube invented just for the BPR, or is it a commonly used device in physics?
  15. Could you give me a figure of the average slip during an landslide (Is it 1 mm, or more like 10 cm ?...)
  16. What's the cost of a BPR installation?
  17. What is a tsunami?
  18. What causes tsunamis?
  19. Have you ever been in a tsunami?
  20. How long have you been a research scientist for tsunamis?
  21. How do you think the new warning systems will help the people in Hawaii, California, Washington, and Alaska be better prepared for tsunamis?
  22. What was the reason for you to start doing research on tsunami patterns?
  23. What do you hope to accomplish with tsunami research and how long will it take?
  24. How far do you think you are away from the final goal of tsunami research?
  25. How do scientists gather information and detect tsunamis?
  26. Is there more than one way to detect tsunamis?
  27. How does that information help us to create better tsunami warning systems?
  28. Is there anything scientists learned from the Dec 26, 2004 Sumatra tsunami in particular?
  29. Did this last tsunami prove to scientists that current detection and warning systems are effective or not? If not, what are scientists doing now to improve those systems?
  30. What do you think is the worst tsunami ever that was created by a volcanic eruption?
  31. When did you first get interested in tsunamis?
  32. What year was the first tsunami recorded? (I have found more than one answer to this.)
  33. What is the worst tsunami to ever hit the United States ( NOT including Hawaii and Alaska?)
  34. What can we do to prepare for a tsunami and when one strikes?
  35. Where do I find a map showing the location of the tsunami warning centers and the DART buoys?
  36. Atlantic Tsunami?
  37. Crumbling Volcano Threatens Atlantic, Caribbean Coastlines
  38. Guatemala tsunami hazard?
  39. What was the Largest Tsunami recorded in the Northwest?
  40. Scientific American Article on Tsunamis by Frank I. Gonzalez
  41. How can we make a homemade simulation of a tsunami?
  42. What time did the Sumatra tsunami (26 Dec 2004) occur?
  43. How many people were killed in the (26 Dec 2004) Sumatra tsunami?
  44. How do tsunamis differ from other water waves?
  45. What is the average height of a tsunami?
  46. Why is the east coast of North America not affected by tsunamis?
  47. How has the tsunami warning system improved since the Indonesian (Sumatra) tsunami on December 26, 2004?
  48. What was the biggest tsunami? What was the outcome?

  1. What is the mathematical formula for the speed of a tsunami?

    The approximate speed of a tsunami, c, is given by

      c = sqrt(g*h)

      where

      g = 9.8 m/s^2 = acceleration due to gravity
      h = water depth in meters
      c = wave celerity(or speed) in m/s

    The speed is given in m per sec by the rule, so you have to convert to km per hour by multiplying the answer by 3.6. This expression is derived from linear long wave theory, and the approximation is good from about 100 m to the deepest ocean depths.

    The average depth of the ocean is about ~ 4500 m or so, therefore c ~ 210 m/s ~ 756 km/hour

    A tsunami in only 1000 m of water would travel at 99 m per sec = 356 km/hour A tsunami in 5039 m of water would travel at 800 km/hour. A tsunami in 6000 m of water would travel at 873 km/hour.

    So a tsunami travels at different speeds in the ocean, slow in shallow water and fast in deep water. There are many places in the ocean deeper than 5000 m, but you should probably use the average depth, and therefore an average speed of about 750 km per hour.

    Authority: Dr. Frank Gonzalez, NOAA Center for Tsunami Research

  2. What was the highest tsunami?

    The highest, reliably measured tsunami on record occurred in Lituya Bay, Alaska. This unusual event was caused by a massive landslide that fell into the bay on July 9, 1958. The resulting wave surged up the slope on the opposite side of the narrow bay to a height of 518 m(1,700 ft). Some scientists believe that even higher tsunamis have occurred a long time ago when asteroids, or large meteors, fell into the ocean. Two areas where studies are underway to look for evidence of such tsunamis are Hawaii and the coast of the Gulf of Mexico.

    Usually, a tsunami is generated when an offshore earthquake moves the ocean bottom in the vertical direction. The waves then propagate towards the coast, growing larger as the water becomes more shallow. Measurements in the last 10 years have documented a 32 m maximum wave height in Okushiri, Japan, and 26 m height on Flores Island Indonesia. These were exceptionally high values due to topographic and bathymetric situations that were somewhat special. More typically, the heights of 10 destructive tsunamis in the Pacific since 1990 ranged from about 3 to 15 m; these claimed more than 4000 lives.

    If you want to explore the issue in more detail, I invite you to visit NOAA's National Geophysical Data Center site. The site offers a historical tsunami database that can be searched on-line.

    Authority: NOAA Center for Tsunami Research

  3. Does a tsunami affect the weather?

    No : Tsunamis are very short-lived events that affect water levels but not the weather.

    In terms of unusual temperatures and the other atmospheric phenomena that seem too anomalous this winter, a good source of information is the recent story in the NOAA Magazine that can be found at http://www.noaanews.noaa.gov/stories2005/s2389.htm. (This story links to a number of websites with additional seasonal and climatic information.)

    Authority: Dr. Hal Mofjeld, NOAA Center for Tsunami Research

  4. What is the current tool used to detect tsunamis?

    Tsunamis are detected by open-ocean tsunami buoys and by coastal tide gages. These instruments report their information in real-time to tsunami warning centers (one center in Alaska, another in Hawaii, and a third to be installed soon in Puerto Rico).

    Besides the direct observations, the amplitudes of tsunamis are also estimated from the size and type of earthquake that may have generated them. The warning centers receive earthquake (seismic) data from many sites as well as analyses of this information from earthquake centers. Since seismic waves travel much faster than tsunamis, the earthquake information is often available hours before the tsunamis are able to travel across the ocean. This is much help for people near the earthquake, however, since the local tsunami is there often within minutes. It is that easy to estimate the strength of a tsunami from the character of an earthquake. Hence, there are false alarms. It is hoped that the direct tsunami observations will reduce the number of these.

    Local tsunamis are also generated by underwater landslides and volcanoes. There is some research being done to better understand these types of tsunamis and to develop early detection methods for them.

    Authority: Dr. Frank Gonzalez, NOAA Center for Tsunami Research

    References and more info: DART Tsunami Buoys

  5. Is it possible for a tsunami to hit the East Coast? Has it ever happened?

    In principle, dangerous tsunamis could strike the East Coast. However, there aren't the large number of marine earthquakes in the Atlantic as compared with the Pacific Ocean.Mo

    The two reported tsunamis in the Atlantic are the 1755 Lisbon tsunami (which killed 60,000 people) and the smaller 1929 Grand Banks tsunami that struck eastern Canada (which killed 27). There is also evidence of a prehistoric tsunami in northern Europe that was caused by a gigantic submarine landslide off Norway.

    Authority: Dr. Frank Gonzalez, NOAA Center for Tsunami Research

  6. Are tsunamis measured on a scale similar to those of tornadoes and hurricanes?

    There is a tsunami intensity scale, although it is not used much anymore. Nowadays, tsunamis are usually described by their heights at the shore and the maximum runup of the tsunami waves on the land.

    Authority: Dr. Frank Gonzalez, NOAA Center for Tsunami Research

  7. Do tsunamis lose speed as they approach land?

    Tsunamis do slow down as they approach land because the water is shallower there. As they slow down, conservation of energy requires that the amplitudes of the waves grow larger.

    Authority: Dr. Frank Gonzalez, NOAA Center for Tsunami Research

  8. What type of force is needed to allow a tsunami to travel a long distance?

    Tsunamis are what are called long gravity waves. There are two interacting processes that allow these waves to propagate. The first is the slope of the sea surface caused by the waves, which creates a horizontal pressure force. The second is the piling up (or lowering of sea surface) as water moves with different speeds in the direction that wave form is moving. When these two processes have the right relationship in time, they create propagating waves.

    Authority: Dr. Frank Gonzalez, NOAA Center for Tsunami Research

  9. Could the effects of atomic bombs tested in the Pacific enhance force of waves and tsunamis?

    There is no widely-held belief along scientists that atomic bomb testing has done so. Basically, the energy associated with large earthquakes is many times that released by an atomic bomb. During the Cold War, however, a number of studies were done on the types of local tsunamis that would be generated if a bomb were detonated in the water near cities.

    Authority: Dr. Frank Gonzalez, NOAA Center for Tsunami Research

  10. How do you think the new warnings systems will help people in Hawaii, California, Oregon, Washington, and Alaska be better prepared for tsunamis?

    I'm assuming you refer to the new DART buoys we're developing. These will help make the tsunami warnings faster and more accurate. Right now, the warning centers depend on earthquake data and on tide gage data to assess the danger. The earthquake data tells you how big the earthquake was, and the location of the epicenter.

    If the location is:

    1. in a region that has generated tsunamis in the past -- basically, very seismically active regions of the "Ring of Fire" around the Pacific Rim, where plate tectonics drives the Pacific plate under various continental plates, and
    2. if the earthquake is big enough, i.e., about a magnitude 7 or greater, then it is considered a possible tsunami hazard.

    But the warning center still doesn't know if a tsunami was generated, because it doesn't have a way to measure it, until the tsunami propagates into a nearby harbor and registers on the tide gage.

    That may take a while, and:

    1. it's too late to warn the folks in that particular harbor and
    2. you may have lost a lot of time waiting for the tsunami to register on the tide gage.

    So DART systems are being place close to the potential tsunamigenic zones, offshore in deep water. That way, if a tsunami is generated by the earthquake, you get the measurement right away. Not only that, but you know that it is headed out to sea and you can warn communities across the ocean that a tsunami is heading toward them.

    See also:



    Authority: Dr. Frank Gonzalez, NOAA Center for Tsunami Research

  11. What was the reason you started doing research on tsunami patterns? What do you hope to accomplish with this tsunami research and how long will it take? How far do you think you are from your goal?

    Understanding tsunami patterns is very important, because the DART buoys are very expensive to build, deploy and then maintain, so we can't put as many of them out in the ocean as we would like to. That means that when a tsunami is generated, we might only get one or two measurements of the tsunami. So we'll have an incomplete picture of what's going on in other parts of the ocean.

    For example, the DART buoy might be in a part of the ocean where the tsunami is small, but there may be other parts of the ocean without a DART buoy where the tsunami is very big. So we don't get a measurement of the big part of the tsunami. But if we understand tsunami patterns for a whole lot of different earthquake sizes and locations, then we can compare these patterns with the DART measurements we have, and find the pattern that agrees best with the measurements. If we find one that agrees well with the DART measurements, then we have some confidence in using the pattern to predict the wave height in places that we don't have measurements.

    So the numerical model that generates the patterns can be thought of as a tool to "fill in the gaps" that exist in the measurements. However, the tsunami problem is very difficult and complex, so our models, even though they are accurate enough to give us useful guidance, are not perfect. So we have to develop this warning tool as carefully as we can, because peoples lives are at stake, and that takes time. We hope to finish our tsunami pattern development for Hawaii in about 3 years, and we hope to have a network of six DART buoys in about 2 years.

    Authority: Dr. Frank Gonzalez, interviews in 1998, NOAA Center for Tsunami Research

  12. Are tsunamis more (or less) dangerous on islands or on normal coasts? Is Hawaii hit so often because it's an island or because it's "in the way" of most tsunamis in the Pacific?

    I read somewhere that the most dangerous tsunamis for Hawaii are those generated by local earthquakes (on the islands itself). I don't understand: wouldn't the tsunami flee the island if it's generated by it? The article seemed to suggest that an earthquake under one of the islands implied a violent tsunami on hawaiian beaches shortly after.

    Because Hawaii is in the middle of the North Pacific and because this ocean is surrounded by a many earthquake/tsunami generating regions, Hawaii tends to receive many trans-oceanic tsunamis. Also, volcanic islands tend to have steep, unstable slopes where landslides can occur. The southeastern coast of the Island of Hawaii (with active volcanoes and ground movement) has had two major landslides in the past 150 years that have generated dangerous tsunamis.

    While most of the tsunami energy does radiate out to sea, some remains near the coast. There are two reasons for this. The first is that tsunami waves tend to turn toward shallow water and can be trapped near the coast in the form of 'edge waves'; these can propagate right around an island. The second is the reflection of tsunami waves that occurs when the wave encounter the sharp change in water depth between the shallow areas just off the coast and the deep ocean water farther away from the island.

    The reason that the landslide tsunamis reach the beach so quickly is that they have only a short distance to propagate away from the landslide area before they reach the beach.

    Authority: Dr. Frank Gonzalez, interviews in 1998, NOAA Center for Tsunami Research

  13. Why does the amplitude of the wave rise when the tsunami reaches a beach?

    I read that it was because the wave's energy, proportional to (amplitude)2, remained constant. I don't see how this explains anything. What's more, isn't there a kinetic term in the wave's energy?

    What remains constant as a tsunami wave propagates is the energy flux, which is the product of the wave energy density times the group velocity of the wave. One way to understand why the flux is conserved is to imagine a box-shaped area in the ocean through which tsunami waves propagate. Unless the same amount of energy propagates out of the box that propagated in, same wave energy must remain inside the box. However, this is not possible with an open box.

    If one side of the box is in deep water H_0 and the opposite side is in shallow water H_1 , then the group velocity c = (gH)^1/2 is less on the shallow side. Since the flux is proportional to c A^2 , the amplitude must increase as the waves move into shallower water.

    The issue of conservation of energy is subtle when it comes to waves. Actually, when a group of waves enters an area that was previously still, the background water level drops (releasing potential energy) while the wave group propagates through the area and rises back to its original level (regaining potential energy) after the wave group has passed. This is a different process than what goes on to conserve energy flux.

    Authority: Dr. Frank Gonzalez, NOAA Center for Tsunami Research

  14. Was the Bourbon tube invented just for the BPR, or is it a commonly used device in physics?

    The Bourbon tube is a commonly used device in physics that was adapted for use in ocean pressure measurements. It is used to convert changes in pressure into some other quantities, such as an angle of rotation for a mirror or a frequency of oscillation of a crystal, that can be recorded. Note: BPR is bottom pressure recorder, used in measuring the height of a tsunami wave in the open water.

    Authority: Dr. Frank Gonzalez, NOAA Center for Tsunami Research

  15. Could you give me a figure of the average slip during an landslide (Is it 1 mm, or more like 10 cm ?...)

    Landslides slips are typically hundreds to thousands of meters. This is in contrast to earthquake slips which are tens of centimeters (not causing dangerous tsunamis) to several meters.

    Authority: Dr. Frank Gonzalez, NOAA Center for Tsunami Research

  16. What's the cost of a BPR installation?

    The cost of a DART/BPR (Bottom Pressure Recorder) installation to obtain data in real-time is $100,000-200,000, plus the cost of periodically replacing the equipment. Self-recording systems for use in research are cheaper Note: BPR means bottom pressure recorder, used to measure the height of a tsunami in the ocean.

    Authority: Dr. Frank Gonzalez, interviews in 1998, NOAA Center for Tsunami Research

    References and more info: DART buoy

  17. What is a tsunami?

    A tsunami is a wave in the ocean or in a lake that is created by a geologic event. They used to be called tidal waves or seismic sea waves.

    Authority: Dr. Hal Mofjeld, NOAA Center for Tsunami Research

  18. What causes tsunamis?

    Tsunamis are most often caused by earthquakes and landslides. These push the water upward, sideways or downward to create the tsunami waves. Volcanic eruptions can also cause tsunamis. There is evidence than in the distant past, asteroids and comets striking the Earth have created enormous tsunamis.

    Authority: Dr. Hal Mofjeld, NOAA Center for Tsunami Research

  19. Have you ever been in a tsunami?

    Many years ago, I was camped on a beach along the coast of Washington State. The 1964 Alaska Earthquake created a tsunami which struck the West Coast at night. If it had been high enough where I was and if the tide had been higher, I would have had real problems. However, nothing happened and I only heard about the tsunami a day or two later.

    My wife was once in Hawaii when a tsunami evacuation was called. After a number of hours, it was determined that the wave was too small to be dangerous; and people were allowed to go back to their hotels.

    Authority: Dr. Hal Mofjeld, NOAA Center for Tsunami Research

  20. How long have you been a research scientist for tsunamis?

    I've been doing tsunami research for about ten years. Before then, I did teach classes at the University of Washington in which one of the topics was tsunamis

    Authority: Dr. Hal Mofjeld, interview in 1998, NOAA Center for Tsunami Research

  21. How do you think the new warning systems will help the people in Hawaii, California, Washington, and Alaska be better prepared for tsunamis?

    The tsunami mapping project will give emergency managers a better idea of which evacuation routes to pick and the places where people can go to be safe from a tsunami. Signs are being put up along these routes to show the way to the evacuation sites. The new buoy systems will quickly give the tsunami warning centers better information about the tsunamis.

    These centers will then be able to send out more accurate warning information as to which areas may be in danger from a tsunami. Hopefully, this will decrease the number of false alarms. Tide gages will measure the heights of later waves in tsunamis. This information will be very useful for guiding rescue operations and for calling the all-clear.

    Many people assume that the tsunami is over after the first wave or two, but this is not true. Later waves, especially at high tide, can be very dangerous.

    See also:



    Authority: Dr. Hal Mofjeld, NOAA Center for Tsunami Research

  22. What was the reason for you to start doing research on tsunami patterns?

    The tsunami mapping effort began because it was realized that only a few coastal communities had any information about how tsunamis might affect them. This work is being part of the National Tsunami Hazard Mitigation Program, in which Federal agencies work with states to decrease the impacts of tsunamis. The program focuses on three areas: better maps, better warnings and education. There is a similar program for earthquakes.

    Authority: Dr. Hal Mofjeld, interview in 1998, NOAA Center for Tsunami Research

  23. What do you hope to accomplish with tsunami research and how long will it take?

    This research is meant to fulfill the goals of the national program, aiming to reduce the loss of life and property due to tsunamis. The first set of maps has been produced and about half of the tsunami buoys are in place. Much of the work will be completed in two years. The maps that have been done so far are for the communities that are most at risk from tsunamis. Maps for other coastal areas will also be produced as time permits.

    Authority: Dr. Hal Mofjeld, interview in 1998, NOAA Center for Tsunami Research

    References and more info: NOAA Tsunami Website

  24. How far do you think you are away from the final goal of tsunami research?

    Producing the tsunami maps will be an ongoing process. One thing that is missing right now is the estimate of how strong the water currents are during a tsunami. That is, the maps only tell us how high the water might get but not how fast it is moving. However, these currents do a lot of the damage. It will take some time to develop a reliable method for predicting the tsunami currents. Once the first array of buoys is in place, the next issue is how to get other countries to put in buoys of their own. Then we will have much better coverage of areas, like Russia and Japan, where tsunamis are formed that are dangerous to the United States. This may be years off. In the meantime, we will make use of island tide gages.

    See also:



    Authority: Dr. Hal Mofjeld, interview in 1998, NOAA Center for Tsunami Research

  25. How do scientists gather information and detect tsunamis?

    Tsunami scientists gather data from tide gages and do field surveys in areas hit by tsunamis to better understand the behavior of real tsunamis. This information is then used to tune computer models that can be applied to other areas. I'm assuming you refer to the new DART buoys we're developing. These will help make the tsunami warnings faster and more accurate. Right now, the warning centers depend on earthquake data and on tide gage data to assess the danger. The earthquake data tells you how big the earthquake was, and the location of the epicenter.

    If the location is:

    1. in a region that has generated tsunamis in the past -- basically, very seismically active regions of the "Ring of Fire" around the Pacific Rim, where plate tectonics drives the Pacific plate under various continental plates, and
    2. if the earthquake is big enough, i.e., about a magnitude 7 or greater, then it is considered a possible tsunami hazard.

    But the warning center still doesn't know if a tsunami was generated, because it doesn't have a way to measure it, until the tsunami propagates into a nearby harbor and registers on the tide gage.

    That may take a while, and:

    1. it's too late to warn the folks in that particular harbor and
    2. you may have lost a lot of time waiting for the tsunami to register on the tide gage.

    So DART systems are being place close to the potential tsunamigenic zones, offshore in deep water. That way, if a tsunami is generated by the earthquake, you get the measurement right away. Not only that, but you know that it is headed out to sea and you can warn communities across the ocean that a tsunami is heading toward them.

    See also:



    Authority: Dr. Hal Mofjeld, NOAA Center for Tsunami Research

  26. Is there more than one way to detect tsunamis?

    Tsunamis are detected and measured by coastal tide gages and by tsunami buoys in the deep ocean. The tide gages measure the tsunami wave directly. In the deep ocean, sensors on the ocean floor detect the pressure signature of tsunami waves as they pass by. Sometimes by chance a satellite that can measure water levels passes over a tsunami and detects it; this was the case during the tsunami in the Indian Ocean.

    See also:



    Authority: Dr. Hal Mofjeld, NOAA Center for Tsunami Research

  27. How does that information help us to create better tsunami warning systems?

    For improved tsunami warning systems, the data collected immediately after a tsunami is generated will be used as input into computer models to forecast the heights of the tsunami when it reaches the shore. The data are presently being used to verify that a tsunami has been generated. This is important since sometimes large earthquakes do not generate dangerous tsunamis but other times they do.

    See also:



    Authority: Dr. Hal Mofjeld, NOAA Center for Tsunami Research

  28. Is there anything scientists learned from the Dec 26, 2004 Sumatra tsunami in particular?

    Scientists are presently doing field surveys and setting up computer models, with the expectation that much will be learned from this research. Once this work is done, we'll know a lot more about the details of the earthquake and tsunami. The one surprise that the fieldwork has shown so far is that the height of the tsunami at Banda Aceh, Sumatra, was much higher than was expected.

    Authority: Dr. Hal Mofjeld, NOAA Center for Tsunami Research

  29. Did this last tsunami prove to scientists that current detection and warning systems are effective or not? If not, what are scientists doing now to improve those systems?

    There was no warning system in the Indian Ocean The tsunami did show the value of having one, and many governments are stating that one like the system in the Pacific Ocean needs to be put into the Indian Ocean.

    Scientists are working to expand the coastal and deep ocean measurement systems, improve the global earthquake measurement array, do more detailed tsunami modeling using computer models, help to educate the public on looking for natural signals of tsunamis (earthquake shaking, withdrawal of water from shore, roaring sounds from the ocean), and improving communication systems to warn people quickly in potentially affected areas.

    See also:



    Authority: Dr. Hal Mofjeld, NOAA Center for Tsunami Research

  30. What do you think is the worst tsunami ever that was created by a volcanic eruption?

    The worst tsunami created by a volcanic eruption was the one in 1883 that occurred when the volcano Krakatoa had an explosive eruption. Over 36,000 people were killed by this tsunami near Java, Indonesia, where Krakatoa is located; many villages and towns were also destroyed.

    Authority: Dr. Hal Mofjeld, NOAA Center for Tsunami Research

  31. When did you first get interested in tsunamis?

    I became interested in tsunamis in the mid-1980's when this became an important research area at the Pacific Marine Environmental Laboratory where I work.

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

  32. 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

  33. What is the worst tsunami to ever hit the United States ( NOT including Hawaii and Alaska?)

    The 1918 tsunami that struck Puerto Rico killed 42 people. In terms of the U.S. Mainland, the 1964 tsunami from Alaska that struck Washington State, Oregon and California caused the most loss of life (11 people in Crescent City, California) and property damage.

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

  34. What can we do to prepare for a tsunami and when one strikes?

    "Are You Ready?" - FEMA Disaster Preparedenss Booklet (pdf)

    Surviving a Tsunami - Lessons from Chile, Hawaii, and Japan / U.S. Geological Survey

    CBS News Disaster Links - A comprehensive site of disaster-related links

    Explanation of Tsunami Bulletins - Information, Warning, Watch, Advisory

    See also:



    Authority: NOAA Center for Tsunami Research

  35. Where do I find a map showing the location of the tsunami warning centers and the DART buoys?

    Operational responsibility for the DART network was transferred from PMEL to the National Data Buoy Center (NDBC) in 2001. As such, all realtime data are displayed on the NDBC web site.

    A map showing the locations of the 6 U.S. operated buoys appears on the NDBC site as well. A 7th buoy is in operation off the coast of Chile. This buoy is sited at 19 deg 42.498 min South, 74 deg 49.14 West and is owned and operated by the Chilean Government.

    The two U.S. NWS tsunami warning centers are 1) West Coast/Alaska Tsunami Warning Center (WCATWC) located in Palmer, Alaska, and 2) located in Ewa Beach, Hawaii. A crude map of their locations appears as part of the DART animation accessible from the DART Mooring System page.

    Authority: Marie Eble, January 5, 2005, NOAA Center for Tsunami Research

  36. Atlantic Tsunami?

    Usually, tsunamis are generated by underwater earthquakes; sometimes the earthquake will trigger an underwater landslide that can add to the height of a tsunami. For example, in 1929, a magnitude 7.2 earthquake near the Grand Banks triggered an underwater landslide and tsunami that caused 51 fatalities in Newfoundland. Such earthquakes on the east coast are rare. Recently, scientists did discover evidence that underwater landslides MAY have occurred off the east coast in the past. If true, this suggests that such slides may also occur in the future, perhaps triggered by a rare east coast earthquake, and perhaps accompanied by a tsunami. So such an event may be possible, and prudence demands the hazard assessment that the east coast scientists plan to conduct, even though the probability of such an event is still considered very low

    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: Dr. Frank Gonzalez, NOAA Center for Tsunami Research

  37. 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

  38. Guatemala tsunami hazard?

    Offshore of Central America lies the Middle America trench that marks the site of where the continental land collides with, and overrides, the seafloor in a process called "subduction." The zone of subduction extends beneath Guatemala and is the source of many of the large destructive earthquakes in the country. When large earthquakes occur in the shallowest parts of the subduction zone, either beneath the sea or near the shore, the seafloor can be disturbed enough to generate a local tsunami. Another possibility is that the earthquake may cause a landslide under the sea. This can also generate a local tsunami.

    In the last 100 years there have been at least 2 earthquakes that caused local tsunamis in Guatemala. One in February 1902, centered more off El Salvador, caused much damage and took 185 lives in Guatemala and El Salvador. Another magnitude 7.1 earthquake in October 1950, located off the coast of Guatemala, generated a small tsunami that ranged up to 2 meters in run up on the Guatemalan coast.

    As far as I know, there is no formal national or regional tsunami warning system for Guatemala or Central America. The only protection one can have from a local tsunami is to take immediate action to go to a place of refuge, preferably someplace that's at least 10 meters above the sea, as soon as possible after feeling an earthquake. In the worst case that may not even be enough but generally it is. As far as "feeling an earthquake" is concerned, I mean either 1) a strong earthquake where it is difficult to stand and buildings are starting suffer damage, or 2) a gentle rocking motion that continues for over a few minutes. A third clue would be a recession of the sea far below the normal low tide. In this case you may not feel an earthquake. It may be that a lesser-sized earthquake has caused a landslide off shore that generated the tsunami. This, of course, would be difficult to detect at night on a sparsely populated coast.

    If the situation is such that there is no refuge above the height of 10 meters, then the best that can be done is to get as far away from the ocean as one can. If the peninsula is a kilometer or so wide, then getting over to the shore of the estero may be all right. If its much narrower, getting in boats and crossing the estero or driving off the peninsula could possibly be considered. The main thing is to have a plan of escape from the tsunami in place before it strikes. This is not an easy thing to do for such rare but dangerous events.

    The final suggestion is to try to relocate permanently a kilometer or two away from the coast or a couple of tens of meters above sea level. I realize this may not be possible but it is the safest.

    Authority: International Tsunami Information Center, itic@itic.noaa.gov:, NOAA Center for Tsunami Research

  39. What was the Largest Tsunami recorded in the Northwest?

    The Global Historical Tsunami Database (from the National Geophysical Data Center) shows that largest tsunami wave recorded in the Northwest is a 30m (98 feet) wave on Vancouver Island; it was generated by an Alaska earthquake in 1946.

    The largest one listed for Washington, Oregon and California is a 6.3m (21 feet) wave at Crescent City, California; it was generated by the 1964 Alaska earthquake.



    Authority: Dr. Frank Gonzalez, NOAA Center for Tsunami Research

  40. Scientific American Article on Tsunamis by Frank I. Gonzalez

    TSUNAMI!

    Frank I. Gonzalez
    Pacific Marine Environmental Laboratory
    National Oceanic and Atmospheric Administration
    Seattle, Washington

    Scientific American, 280, 56-65 (1999)
    Copyright © 1999 Scientific American, Inc.
    All rights reserved. Further electronic distribution is not allowed.

    Its awesome fury cannot be diminished, but lesson learned from a rash of disasters this decade --- and a new way to track these killer waves --- will help save lives.



    Authority: NOAA Center for Tsunami Research

  41. How can we make a homemade simulation of a tsunami?

    Here's an idea that's very similar to laboratory
    models that are often used to study tsunamis.
    
         Water Tank or Trough (a couple of feet long)
         Not to scale
    
     Generator                                        Beach
     |           __________                                |
     |          /          \  wave -->                     |
     |_________/            \______________________________|
     |                                                    /|
     | \                                                 / |
     |  \  <- Hinged plastic plate      Fixed Incline-> /  |
     |   \    that pivots up                           /   |
     |____\___________________________________________/____|
    
    The Generating Plate simulates the upward motion of the
    earth, creating a "bump" in the water. The resulting wave
    propagating away toward the beach, or impact area. The
    wave builds in height as the water gets shallower toward
    the beach (due the the Fixed Incline) and hits the shore.
    This will probably work best if the the Generating Plate
    is about a foot long and the water is relatively shallow.
    It can be moved up rapidly using a strong string attached
    to the side away from the pivot, which can be made with
    duck tape. The Fixed Incline should be a gentle slope.
    
    more details:
    
    The basic idea behind tsunami simulations is to show the three 
    stages of tsunami waves: their generation (usually because the 
    ocean bottom moved up or down, or a landslide hit the water), 
    the propagation of the waves from the source region to the impact 
    site (the shallower the water, the slower and more clearer this shows), 
    and the runup on land (usually with a sloping incline, possibly with 
    a small model house for effect). There is a trade-off in size between 
    having the wave model large enough so people can see what's going on 
    but small enough to be portable.
    
    If the instructions for science projects allow, I'd make the model 
    out of clear lucite (perhaps coloring the water light blue), 24 inches 
    long, 6 inches high, and 3 inches wide. The model will work even better 
    if it can be longer, say an additional 6 or 12 inches in length. I'd 
    use clear aquarium glue to put the pieces together, so the seams will 
    hold water.
    
    Some science classes require the use of metric units, like centimeters, 
    instead of English units. In this case, multiplying the values in 
    inches by 2.5 will give a reasonable equivalent in centimeters.
    
    The source end can be vertical if the source is a moving bottom 
    or steeply sloping (one-to-one slope) for a landslide. For the 
    sloping source-end, the end-piece would be 8.5 inches long. The 
    moving bottom can be a 2 inch by 6 inch piece of lucite that has 
    strings attached to each corner (so it can be pulled upward quickly 
    to start the tsunami wave). There may need to be some thin spacers 
    attached under the moving bottom to prevent it from forming a strong 
    suction with the real bottom. You can use a strong plastic bag of 
    sand or sugar sliding into the water to simulate a landslide.
    
    The impact slope should be a foot long and glued at an angle from 
    the top where the side walls end diagonally down to the bottom. 
    This provides a slope of about 27 degree (one-to-two). You'll need 
    to experiment with the amount of water in the model. I'll say it 
    would be good to start with one inch (or 2.5 cm) of water to start. 
    The shallower the water, the slower the waves will travel. If the 
    water is too deep or moving too fast when it hits the far impact end, 
    it may splash out of the model. You can lay a short cover shield over 
    the top of that end if this is a problem. Having paper towels 
    around is not a bad idea, nor is having a funnel to use when pouring 
    the water back into the carrying container.
    
    It's a good idea when doing a tsunami demonstration to mention the way 
    that the way water sloshes back and forth after the first wave hits 
    the impact site is very much like real tsunamis behave. These tsunamis 
    slosh back and forth in harbors, so the tsunami danger isn't over 
    after the first wave.
    


    Authority: Dr. Hal Mofjeld, NOAA Center for Tsunami Research

  42. What time did the Sumatra tsunami (26 Dec 2004) occur?

    The tsunami was generated by a magnitude 9.0 earthquake of the west coast of Northern Sumatra at 00:58:53 UTC Sunday 26 December 2004. The India tectonic plate subducted beneath the Burma plate along the Sunda trench. This megathrust earthquake created a vertical displacement of water, thereby creating the subsequent tsunami.

    The USGS Earthquake Hazards Program provides detailed information on the earthquake including the time of the event in other time zones.

    Our program's event page provides modeled animations of the tsunami and a list of related links.

    January 27, 2005

    Authority: NOAA Center for Tsunami Research

  43. How many people were killed in the (26 Dec 2004) Sumatra tsunami?

    The number of people who where killed is still being updated (as of Feb. 18, 2005).

    Indian Ocean Earthquake & Tsunami Emergency Update
    The Center of Excellence in Disaster Management and Humanitarian Assistance (COE).

    The United Nations News Service is also a resources for more information on loss of life due to the tsunami.

    USGS News Release: 2004 deadliest in nearly 500 years for earthquakes.



    Authority: NOAA Center for Tsunami Research

  44. How do tsunamis differ from other water waves?

    Tsunami waves are shallow-water waves with long periods and wave lengths. (A wave is classified a shallow-water wave when the ratio between the water depth and its wavelength gets very small. The speed of a shallow-water wave is equal to the square root of the product of the acceleration of gravity (32ft/sec/sec or 980cm/sec/sec) and the depth of the water.) Shallow water waves are different from wind-generated waves (the waves many of us have observed on the beach). Wind-generated waves usually have period (time between two succesional waves) of five to twenty seconds and a wavelength (distance between two successional waves) of about 50 to 600 feet (15 to 200 meters) A tsunami can have a period in the range of 10 minutes to 1 hour and a wavelength in excess of 700 km (430 miles).

    Authority: NOAA Center for Tsunami Research

  45. What is the average height of a tsunami?

    Most tsunamis are very weak and have heights of only a few inches (or centimeters). However, once in a while there is tsunami that is really dangerous. Near the place where they are created, these larger tsunamis may have heights of many feet (meters). As they spread out or move into the deep ocean, their heights decrease to a foot or less. However their heights increase again as the tsunami waves reach shallow water near impact areas. Computer models for tsunamis along the coasts of California, Oregon and Washington State are showing that the expected heights for these larger tsunamis is around 30-70 feet.

    Authority: Dr. Hal Mofjeld, interview in 1998, NOAA Center for Tsunami Research

  46. Why is the east coast of North America not affected by tsunamis?

    Most tsunamis are earthquake generated so they occur in oceans where significant seismic, or earthquake, activity is common. There are earthquakes in the Atlantic, and some tsunamis have been generated in the past, but the greatest risk is for Pacific communities. Seismic activity is greatest in the Pacific Ocean, due to movement of the Earth's plates creating many subduction zones around the Pacific Ocean Basin known as the 'Ring of Fire'. The Pacific Tsunami Warning Center explains where tsunamis occur in a frequently asked question section. Go to http://www.prh.noaa.gov/ptwc/faq.php and read the answer to question #8.

    Authority: NOAA Center for Tsunami Research

  47. How has the tsunami warning system improved since the Indonesian (Sumatra) tsunami on December 26, 2004?

    The tsunami warning system has improved dramatically, particularly in the Pacific, following the 2004 Indian Ocean event. A good example of that is the increase in the number of DART® buoys (tsunami sensors) deployed in ocean waters. This number has gone from 8-9 buoys in 2004 to 37 in October 2009 in the Pacific Ocean alone. Additional buoys up to a total of 48 have been deployed in the Indian and Atlantic Oceans as well. The improvements to the warning system have not been only in the form of additional instrumentation. More sophisticated data analysis techniques, incorporating real time numerical simulations (while the tsunami is propagating) have been developed by the NOAA Center for Tsunami Research (NCTR) in Seattle and are currently undergoing testing and evaluation by the NOAA Tsunami Warning Centers in Alaska and Hawaii.

    Authority: NOAA Center for Tsunami Research

  48. 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