A tsunami is a series of water waves caused by the displacement of a large volume of a body of water, generally an ocean or a large lake. Earthquakes, volcanic eruptions and other underwater explosions(including detonations of underwater nuclear devices), landslides, glacier calvings, meteorite impacts and other disturbances above or below water all have the potential to generate a tsunami. Tsunami waves do not resemble normal sea waves, because their wavelength is far longer. Rather than appearing as a breaking wave, a tsunami may instead initially resemble a rapidly rising tide, and for this reason they are often referred to as tidal waves.
Tsunamis generally consist of a series of waves with periods ranging from minutes to hours, arriving in a so-called “wave train”. Wave heights of tens of metres can be generated by large events. Although the impact of tsunamis is limited to coastal areas, their destructive power can be enormous and they can affect entire ocean basins; the 2004 Indian Ocean tsunami was among the deadliest natural disasters in human history with over 230,000 people killed in 14 countries bordering the Indian Ocean.
The Greek historian Thucydides suggested in his late 5th century BC, History of the Peloponnesian War, that tsunamis were related to submarine earthquakes, but the understanding of a tsunami’s nature remained slim until the 20th century and much remains unknown. Major areas of current research include trying to determine why some large earthquakes do not generate tsunamis while other smaller ones do; trying to accurately forecast the passage of tsunamis across the oceans; and also to forecast how tsunami waves would interact with specific shorelines.
A tsunami is a series of ocean waves that sends surges of water, sometimes reaching heights of over 100 feet (30.5 meters), onto land. These walls of water can cause widespread destruction when they crash ashore.
Tsunami are waves caused by sudden movement of the ocean due to earthquakes, landslides on the sea floor, land slumping into the ocean, large volcanic eruptions or meteorite impact in the ocean. Earthquakes
Most tsunami are caused by large earthquakes on the seafloor when slabs of rock move past each other suddenly, causing the overlying water to move. The resulting waves move away from the source of the earthquake event. Landslides
Underwater landslides can cause tsunami as can terrestrial land which slumps into the ocean. View our landslide generation animation which demonstrates how a landslide induces a tsunami. Volcanic eruptions
Less common are tsunami initiated by volcanic eruptions. These occur in several ways: destructive collapse of coastal, island and underwater volcanoes which result in massive landslides pyroclastic flows, which are dense mixtures of hot blocks, pumice, ash and gas, plunging down volcanic slopes into the ocean and pushing water outwards a caldera volcano collapsing after an eruption causing overlying water to drop suddenly.
An earthquake is the shaking of the earth that occurs after pieces of the crust of the Earth suddenly shift. The term earthquake describes the sudden slip on a fault and includes the ground shaking and radiating seismic energy that is caused by the slip. Volcanic activity, or other geologic processes, may cause stress changes in the earth that can also result in an earthquake. Earthquakes can occur anywhere in the world although some areas of the globe are more likely to experience an earthquake than others.
Earthquakes occur in all types of weather, in all climate zones, in all seasons of the year, and at any time of day making it impossible to predict with any certainty when an earthquake is likely to occur. The best seismologists (scientists who study earthquakes) can do is to look at the historical record of earthquake activity for any geographical area and use this data to calculate the probability of an earthquake occurring in the future. Earthquake prediction is still in the future.
A tsunami is a series of sea waves that can be caused by earthquakes or landslides at or beneath the sea floor. The displacement of the sea floor that occurs during certain large submarine earthquakes and landslides causes displacement of large volumes of the sea water above it producing large, fast moving waves. When a coast line experiences a tsunami it can be due to an earthquake near the coast or due to a quake occurring in a distant part of the ocean. Coastal areas may experience little or no damage from an earthquake but can be devastated by the resulting tsunami.
2010 Haiti Earthquake
Haiti suffered one of the largest earthquakes in more than 200 years in 2010. The 7.0 magnitude earthquake was centered about 10 miles from Port-au-Prince and set off a swarm of tsunamis that killed three people and destroyed several homes. The waves were averaged to be about 10 feet high.
2010 Sumatra Earthquake/Tsunami
he October 2010 Sumatra earthquake occurred on the same fault as the 2004 Indian Ocean earthquake. The second time wasn’t as disastrous but there was still substantial damage. This time around the earthquake was 7.7 on the Richter scale and developed a tsunami that struck the Mentawai Islands. The tsunami, which had a wave of 9 feet, destroyed many of the villages on the island. It displaced more than 20,000 people and reportedly killed 435.
2010 Chile Earthquake/Tsunami
A 8.8 magnitude earthquake struck Chile on February 27, 2010 with intense shaking that lasted for about three minutes. It triggered a tsunami that destroyed several coastal towns in south-central Chile. The tsunami raced through the Pacific Ocean that 53 countries had to post warning, though there was little damage as it moved past Hawaii, Australia and Japan. The death toll was 521 victims.
2011 Tohoku Earthquake/Tsunami
The 9.0-magnitude megathrust earthquake that hit the Tohoku region of Japan on March 11, 2011 was the largest earthquake to have ever hit the country. Japanese Prime Minister Naoto Kan even called it “the toughest and most difficult crisis for Japan” since the end of World War II. The tsunami that traveled along the Pacific coast of Japan’s northern islands was measured to be at least 9.8 feet high. Entire towns and cities were swept away and about 5,692 are said to be dead, with 9,522 missing and 2,409 injured.
1771 Great Yaeyama Tsunami
On April 24, 1771, the Yaeyama Great Earthquake caused the formation of the
1771 Great Yaeyama Tsunami. The tsunami hit both the Ishigaki and Miyakojima Island of Japan and killed a total of 12,000 people. Agriculture was severely damaged and the population decreased about one-third of what it was. The tsunami at Ishigaki reportedly reached a height of 262 feet.
1792 Mount Unzen
The 1792 eruption of Mount Unzen in western Kyushu, Japan is the most deadliest volcanic eruption ever in Japan. It caused a megatsunami that reached up to 330 feet and killed 15,030 people.
1896 Meiji-Sanriku Earthquake
The 1896 Meiji-Sanriku earthquake hit Japan on a day when the country was celebrating both the return of soldiers from the Sinto Japanese War and a Shinto holiday. The 7.2 magnitude earthquake that took place was small but the tsunami that struck the coast of Sanriku 35 minutes later was much greater. Waves as high as 125 feet were measured and nearly 9,000 homes were destroyed. 22,070 were reported dead and an unusually high count of victims with fractured skulls and broken or missing limbs. Hawaii also suffered some destruction from the tsunami as waves of 30 feet were measured there.
1868 Arica Earthquake/Tsunami
The estimated 8.5 to 9.0 magnitude earthquake near Arica (then part of Peru, now part of Chile) in 1868 nearly destroyed all of Arica and its surrounding cities. The tsunami it produced almost completely destroyed the port city of Pisco. It also caused some damage in Hawaii, New Zealand and Japan. About 25,674 casualties were reported. Aug. 27, 1883: Eruptions from the Krakatoa volcano fueled a tsunami that drowned 36,000 people in the Indonesian Islands of western Java and southern Sumatra.
The strength of the waves pushed coral blocks as large as 600 tons onto the shore. June 15, 1896: Waves as high as 100 feet (30 meters), spawned by an earthquake, swept the east coast of Japan. Some 27,000 people died. April 1, 1946: The April Fools tsunami, triggered by an earthquake in Alaska, killed 159 people, mostly in Hawaii. July 9, 1958:Regarded as the largest recorded in modern times, the tsunami in Lituya Bay, Alaska was caused by a landslide triggered by an 8.3 magnitude earthquake. Waves reached a height of 1,720 feet (576 meters) in the bay, but because the area is relatively isolated and in a unique geologic setting the tsunami did not cause much damage elsewhere.
It sank a single boat, killing two fishermen. May 22, 1960: The largest recorded earthquake, magnitude 8.6 in Chile, created a tsunami that hit the Chilean coast within 15 minutes. The surge, up to 75 feet (25 meters) high, killed an estimated 1,500 people in Chile and Hawaii. March 27, 1964: The Alaskan Good Friday earthquake, magnitude between 8.4, spawned a 201-foot (67-meter) tsunami in the Valdez Inlet. It traveled at over 400 mph, killing more than 120 people.
Ten of the deaths occurred in Crescent City, in northern California, which saw waves as high as 20 feet (6.3 meters). Aug. 23, 1976: tsunami in the southwest Philippines killed 8,000 on the heels of an earthquake. July 17, 1998:A magnitude 7.1 earthquake generated a tsunami in Papua New Guinea that quickly killed 2,200. Dec. 26, 2004: A colossal earthquake with a magnitude between 9.1 and 9.3 shook Indonesia and killed an estimated 230,000 people, most due to the tsunami and the lack of aid afterward, coupled with deviating and unsanitary conditions.
The quake was named the Sumatra-Andaman earthquake, and the tsunami has become known as the 2004 Indian Ocean tsunami. Those waves traveled the globe – as far as Nova Scotia and Peru. March 11, 2011: A massive 8.9-magnitude earthquake struck northern Japan, triggering tsunamis that reportedly swept up cars, buildings and other debris. The Japan Meteorological Society has forecast more major tsunamis in the area, with some expected to reach more than 30 feet (10 m) off the coast of Hokkaido, Japan’s second largest island. A tsunami was also generated off the coast of Hawaii, one that could cause damage along the coastlines of all islands in the state of Hawaii, according to the Pacific Tsunami Warning Center. Tsunami warnings are in effect across Hawaii as well.