What is tsunami and its causes pdf
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- A short history of tsunami research and countermeasures in Japan
- Tsunamis Generated By Coastal And Submarine Landslides In The Mediterranean Sea
- 4 Major Reasons for Formation of Tsunami – Explained!
A short history of tsunami research and countermeasures in Japan
Tsunamis are caused by violent seafloor movement associated with earthquakes, landslides, lava entering the sea, seamount collapse, or meteorite impact. The most common cause is earthquakes.
See the percentages on the right for the geological events that cause tsunamis. A disturbance that displaces a large water mass from its equilibrium position can cause a tsunami. In order to understand the role of violent seafloor movement as a major cause of tsunamis, one needs to understand plate tectonics.
They move relative to each other at rates of up to several inches per year. A plate boundary is the area where two plates come into contact. The way one plate moves relative to another determines the type of boundary: spreading, where the two plates move away from each other; subduction, where the two plates move toward each other, with one sliding beneath the other; and transform, where the two plates slide horizontally past each other.
Subduction is the main cause of major tsunami events. There are subduction zones with associated deep-sea trenches off Chile, Alaska, Japan, and Indonesia, for example, that have produced large earthquakes and devastating tsunamis, many of which caused damage and loss of life in the Hawaiian Islands.
Part of the seafloor snaps upward as the tension is released. The entire column of seawater is pushed toward the surface, creating an enormous bulge. As the water flattens out, giant ripples race outward. Landslides, Volcanic Eruptions, MeteoritesSubmarine landslides, which often occur during a large earthquake, can create a tsunami. During a submarine landslide, the equilibrium sea level is altered by sediment moving along the sea floor.
Gravitational forces then propagate the tsunami given the initial perturbation of the sea level. Similarly, a violent marine volcanic eruption can create an impulsive force that displaces the water column and generates a tsunami.
Above water landslides and space borne objects can disturb the water from above the surface. The falling debris displaces the water from its equilibrium position and produces a tsunami.
Unlike ocean-wide tsunamis caused by some earthquakes, tsunamis generated by non-seismic mechanisms usually dissipate quickly and rarely affect coastlines far from the source area.
Tsunamis Generated By Coastal And Submarine Landslides In The Mediterranean Sea
Tsunamis are caused by violent seafloor movement associated with earthquakes, landslides, lava entering the sea, seamount collapse, or meteorite impact. The most common cause is earthquakes. See the percentages on the right for the geological events that cause tsunamis. A disturbance that displaces a large water mass from its equilibrium position can cause a tsunami. In order to understand the role of violent seafloor movement as a major cause of tsunamis, one needs to understand plate tectonics. They move relative to each other at rates of up to several inches per year. A plate boundary is the area where two plates come into contact.
Although tsunami may be caused by landslides, volcanic eruptions or even by the impact of a large meteorite falling on the ocean, most destructive tsunamis are generated by massive undersea earthquakes, occurring at depth less than 50 km with the epicentre or fault line near or on the ocean floor. Image Courtesy : public. A strong undersea earthquake with magnitude greater than 7. Waves are formed as the displaced water attempts to regain its equilibrium under the influence of gravity. It is this vertical movement of the entire water column that generates destructive tsunami waves Fig.
Often a tsunami wave warns of its arrival with roaring and rumbling from the ocean, but sometimes a rising wall of water approaches silently and imperceptibly. A.
4 Major Reasons for Formation of Tsunami – Explained!
The tsunami science and engineering began in Japan, the country the most frequently hit by local and distant tsunamis. The gate to the tsunami science was opened in by a giant local tsunami of the highest run-up height of 38 m that claimed 22, lives. In , the same area was hit again by another giant tsunami. Relocation of dwelling houses to high ground was the major countermeasures. The tsunami forecasting began in
The tsunami that affected the coasts of the Indian ocean on December 26, claimed close to lives, mainly on the island of Sumatra, Indonesia, which suffered overwhelming devastation. This article asks whether a tsunami warning system is needed in the Indian Ocean, where the probability of experiencing a similar catastrophe is very small. In addition, other alternatives, including land use planning and education focused on tsunami risk management, are presented. Their application could considerably reduce financial and human losses if a disaster of this nature was to occur again. Keywords: tsunami, natural hazard, hazard, vulnerability, risk management, warning system, land use planning, education.
The main cause of tsunami generation in the Mediterranean Sea is tectonic activity associated with strong earthquakes. However, tsunami waves are also generated by landslides. From a compilation of 32 reliable cases of landslide tsunamis it comes out that most of them were caused by subaerial landslides or marine slides induced mainly by earthquakes and less frequently by volcanic eruptions.
Known tsunamis of volcanic origin are reviewed and classified according to their causes. Ten causes of volcanic tsunamis are discussed. From the risk point of view, those due to landslides are particularly dangerous.
Although rare, tsunamis have the potential to cause considerable loss of life and injury as well as widespread damage to the natural and built environments. The objectives of this review were to describe the impact of tsunamis on human populations in terms of mortality, injury, and displacement and, to the extent possible, identify risk factors associated with these outcomes. This is one of five reviews on the human impact of natural disasters. Data on the impact of tsunamis were compiled using two methods, a historical review from to mid of tsunami events from multiple databases and a systematic literature review to October of publications. Analysis included descriptive statistics and bivariate tests for associations between tsunami mortality and characteristics using STATA There were , deaths range ,, and 48, injuries range 45,, as a result of tsunamis from to Findings from the systematic literature review indicate that the primary cause of tsunami-related mortality is drowning, and that females, children and the elderly are at increased mortality risk.
Official websites use. Share sensitive information only on official, secure websites. A tsunami can kill or injure people and damage or destroy buildings and infrastructure as waves come in and go out. A tsunami is a series of enormous ocean waves caused by earthquakes, underwater landslides, volcanic eruptions, or asteroids. Tsunamis can:. Happen anywhere along U. Coasts that border the Pacific Ocean or Caribbean have the greatest risk.
The effects of a tsunami on a coastline can range from unnoticeable to devastating. The effects of a tsunami depend on the characteristics of the seismic event that generated the tsunami, the distance from its point of origin, its size magnitude and, at last, the configuration of the bathymetry that is the depth of water in oceans along the coast that the tsunami is approaching. Small tsunamis, non-destructive and undetectable without specialized equipment, happen almost every day as a result of minor earthquakes and other events. They are very often too far away from land or they are too small to have any effect when they hit the shore. When a small tsunami comes to the shoreline it is often seen as a strong and fast-moving tide.
PDF | On 26th of December , Sri Lanka experienced, perhaps its most devastating natural disaster through a impact of a Tsunami. The Tsunami, a | Find.