Tsunamis, commonly called tidal waves by the general public, are large sea waves or surges. These waves can carry a lot of energy from one side of the globe to the other, reeking havoc where ever they make landfall, and as shown by the December 26, 2004 SE Asian event, tsunami's can claim thousands of lives and cause millions of dollars worth of damage to property.
* Many people picture large, breaking waves when they hear the word tsunami. This is usually not the case, however.
* Most tsunamis make landfall as little more than a gigantic surge, as if the tide just moved in way too far way too fast.
* This surging nature of tsunamis is mostly due to the extremely long wavelength, generally on the order of 100-200km.
* A tsunami can turn into a locally, large and breaking wave if the wave energy is concentrated, shortening the wavelength and increasing the amplitude.
* This often happens if the wave enters a bay, fjord or similar feature.
* Tsunamis can be regional, like the recent tsunami in SE Asia, or localized, like the megatsunami in Lituya Bay, Alaska in 1958.
* Regional scale tsunamis are general caused by crustal rebound after a large earthquake, usually associated with a subduction zone
* Localized tsunamis are also generally associated with earthquakes, but the physical cause of the wave is usually due to a landslide or pyroclastic flow.
There are several geologic events that can trigger the propagation of a tsunami
* Earthquakes: generally tectonic rebound at or near a subduction zone, when there is a vertical component to crustal movement that displaces a large volume of the overlying water
* Landslides: often earthquake or volcanically triggered, can be purely submarine or the slide could begin on land and slide into the water (i.e. a collapsing volcano)
* Volcanic activity: usually subaerial, could be pyroclastic flows, lahars, nuees ardants, or collapse of the mountain side
* Impact of a large meteor or asteroid
* A tsunami behaves as a shallow water wave.
* Tsunami's travel in much the same way as your garden variety, wind-propagated water waves: with some combination of transverse and longitudinal movement.
Tsunamis caused by the Earthquake leads to flooding along the coastal environment. This damages any homes. Flooding caused new lakes or sag ponds on the land. Increasing groundwater flow from springs and displacing stream channel. ("Flood Consequences")
The tsunami in Thailand that occurred on December 26, 2004, was by far the largest tsunami catastrophe in human history. It was triggered by a magnitude 9.1-9.3 earthquake along the Indian-Australian subduction zone off the northern coast of Sumatra. The tsunami waves traveled primarily in the east to west direction and caused major damage along the coasts of southern Thailand. Unpredictably, it was a violent earthquake beneath the sea that initiated the massive waves and struck more than a dozen countries in Southern Asia. It also destroyed thousands of miles of coastline and even submerged entire islands permanently. Throughout the region, the tsunami killed more than 150,000 people, and a million more were hurt, homeless, and without food or drinkable water, making it perhaps the most destructive tsunami in the modern history. In spite of peninsular Thailand's location facing the northern part of this subduction zone, the lack of any written historical records, together with the lack of any major local seismic activity, the tsunami caused thousands of fatalities and huge economic losses in the popular tourist regions in Thailand. Immediately after the disaster, numerous organizations and individual citizens have helped out and contributed to this devastating tsunami. Indeed, the tsunami in Thailand was a worldwide event, with significant wave action felt around the world. In this context, I am focusing more on the key features of the tsunami’s natural causes, the psychological effects on citizens, the perspective of socio-economic impacts and the consequences of the tsunami calamity.
TOHOKU, Japan, Friday, Mar. 11 -Yesterday, a 9.0 magnitude Earthquake struck the east of Tohoku, Japan. The epicentre of the earthquake was located approximately 72 km east of Tohoku (38.3 degrees North latitude and 142.4 degrees East longitude), or 130 km east of Sendai as shown by the X in figure 3 below. The focus of the earthquake was 24.4 km under the epicentre. The earthquake therefore caused a tsunami due to the displacing of water above the Pacific Plate. The earthquake and tsunami together have caused approximately 20,000 deaths, 6152 injuries and 2500 people missing. Approximately 90% of these deaths were by drowning. Approximately 140,000 people have been displaced and over 500,000 buildings and structures have been destroyed or damaged. The early warning system of Japan stopped many bullet trains, and many residents received texted warnings of the earthquake and tsunami on their mobile phones giving them time to evacuate. Figures 1 and 2 show exactly how destructive the tsunami caused by the Tohoku Earthquake was.
Out of all the natural disasters that we talk about in class, the most deadly would have to be a Tsunami. Compared to earthquakes, Tsunamis have cause more deaths since 1945. A Tsunami is likely to strike anywhere on the west coast, including Santa Cruz in California – United States – North America – 36:58:24N 122:02:09W. A Tsunami is a giant “wave” of water that is caused by a sudden shift in the sea floor. The wave is a result of the water attempting to regain its equilibrium, which is driven by gravity. The size of the wave is determined by how much the sea floor is moved vertically, and how quickly it shifts. A greater water depth helps as well. They can travel up to five hundred miles an hour and have wave heights of one hundred feet. Earthquakes are the leading cause of Tsunamis. People who live in California are well aware of earthquakes that are frequently caused by the San Andreas Fault. However, not many are aware of the results of earthquakes that occur out in the Pacific Ocean. Tsunamis have also been referred to in the past as seismic sea waves, but Earthquakes aren’t the only cause of this phenomenon. Landslides, nuclear explosions, volcanic eruptions, and extra terrestrial impacts also have great water displacement results.
Earthquakes are caused by tectonic plates moving in the earth's crust. They either move apart or pull together at faults. Two forms of faults are normal faulting where the hanging wall moves downward causing rocks to be pulled apart by tension and reverse faulting, which is the opposite where the hanging wall moves upward casuing rocks to be forced together by tension. These movements cause tectonic plate boundaries called divergent boundaries, convergent boundaries and transform boundaries. Each boundary is different and play a
Then According to Indian Ocean Tsunami: Then and now “The violent upward thrust of the ocean floor at 07:58 local time (00:58 GMT) displaced billions of tonnes of seawater, which then raced towards shorelines at terrifying speeds.” The book says racing but that is just an understatement terrifying speeds means 500 mph. Also In How Scientists and Victims Watched Helplessly.
The change in climate also affect the ocean currents and heat up the land under the water causing tsunamis. For example, The Japan earthquake and tsunami which took place on march 11, 2011.
The National Geographic Society is good source of information, and no person can argue the artistry of its presentation, however, the magazine, and its television and internet productions are directed toward a curious, but mostly naive audience. If searching for an overview, a middle man one may say, National Geographic does provide a history and account of the event in “The Deadliest Tsunami in History” (National Geographic News, Jan 7, 2005). Organized and succinct, the article begins with a few simple facts about the wave making process and tsunami characteristics, even dispelling myths that a tsunami is a single destructive tidal wave, but actually a series of wave building processes resulting from the shifting of the earth undersea due to seismic activity. The article goes on to include human interest stories, not overlooking an account where an Indian man after remembering a National Geographic program, saves the li8ves of more than 1,500 of his fellow villagers. Lastly, the article discusses potential residual hazards of the event, presenting issues such as famine and disease epidemics due to the lack of clean water and food supplies diminished from the disaster.
Tsunamis occur more frequently in the Pacific Ocean as compared to the Atlantic Ocean. The main reason behind this is the “Ring of Fire.”
The 2004 Indian Ocean earthquake and tsunami took place on December 26th, 2004 and had a magnitude of 9.15. The cause of the Sumatra Tsunami was due to the sliding of two tectonic plates. Sumatra, an island in Indonesia, is situated on the boundary of the two plates; part of Sumatra is situated on the India/Australian plate and the other part is on the Eurasian plate. The Indian/Australian plate and Eurasian plate connect on the ocean floor at the boundary, a little over 100 miles off the short of Sumatra. Sumatra was one among the many countries that was impacted by these natural disasters. To fully understand the Sumatra Tsunami one must examine the events that led up to it, what a tsunami is, and the damage caused.
Additionally, this earthquake occurred on a thrust fault. This fault was a subduction zone slip which occurred primarily beneath the ocean were the Pacific plate plunges underneath the North American plate. This sudden upward movement of the sea floor along the rupturing fault generated a massive tsunami. This vertical deformation
Less than an hour after the earthquake, the first of many tsunami waves hit Japan's coastline. The tsunami waves reached run-up heights (how far the wave surges inland above sea level) of up to 128 feet (39 meters) at Miyako city and traveled inland as far as 6 miles (10 km) in Sendai. The tsunami flooded an estimated area of approximately 217 square miles (561 square kilometers) in Japan.
An earthquake occurs abruptly and causes severs damage to people, property, landscape and more. A great mega-thrust earthquake, known as the Great Tohoku Earthquake has shaken Japan at 5:46:24 UTC on March 11, 2011. It caused a severe disaster, including tsunami and nuclear radiation exposure.. This mega-quake located at the latitude 38.297 degree North and longitude of 142.372 degree East, near the east coast of Honshu, Japan (USGS, 2013). An earthquake and tsunami waves caused widespread damage to many areas of Japan. People in Japan are still recovering from the damages.
“Explainer: After an Earthquake, How Does a Tsunami Happen?” Stuff.co.nz, Fairfax New Zealand Limited, 11 Sept. 2017,