Tsunami and Its Causes

Causes of Tsunami, Tsunami and Its Causes ,Tsunami, What is Tsunami, How Tsunami Works, Consequences of Tsunami, Warning and Mitigation

Tsunami and its causes

Tsunami is a Japanese word which means ‘Harbour Wave’. It is a series of travelling ocean waves of extremely long length. Which is generated by disturbances  associated primarily with earthquakes occurring below or near the ocean floor. Underwater volcanic eruptions and landslides can also generate tsunamis. It is a threat to life and property to anyone living near the ocean. Large tsunamis have been known to rise over 100 feet, while tsunamis 10 to 20 feet height can be very destructive and cause many deaths and injuries.

Causes of Tsunami

Tsunamis generally are caused by earthquakes. Not all earthquakes generate it. To generate it earthquakes must occur underneath or near the ocean, be large and create movements in the sea floor. All oceanic regions of the world can experience it, but in the Pacific Ocean there is a much more frequent occurrence of large, destructive tsunamis because of the many large earthquakes along the margins of the Pacific Ocean. Other less common causes of earthquakes are submarine landslides, submarine volcanic eruptions and very rarely a large meteorite impact the ocean.

Propagation of Tsunami

In the open Ocean is tsunami is less than a few feet high at the surface, but its wave height increases rapidly in shallow water. Tsunamis wave energy extends from the surface to the bottom in the deepest waters. As the tsunami attacks the coastline, the wave energy is compressed into a much shorter distance creating destructive, life threatening waves.

Where the ocean is over 20,000 feet deep, unnoticed waves can travel at the speed of a commercial jet plane, nearly 600 miles per hour. They can move from one side of the Pacific Ocean to the other in less than a day. The great speed makes it important to be aware of the tsunami as soon as it is generated. Scientists can predict when a tsunami will arrived since the speed of the waves very with the square root of the water depth. It is travel much slower in shallower coastal water where there wave heights begin to increase dramatically.

Offshore and coastal features can determine the size and impact of tsunami waves. Reefs, bays, entrances to rivers, under sea features and the slope of the beach all help to modify the tsunami as it attacks the coastline. When the tsunami reaches the coast and moves inland, the water level can rise many feet in extreme cases, water level has risen to more than 50 feet for tsunamis of distant origin and over 100 for tsunami waves generated near the earthquakes epicentre.

Consequences of Tsunami

The consequences vary from loss of livelihood for fisherman to unknown damages to coral reefs and flora and fauna. It may takes years for the coral reefs to get back the balance and mangrove stands and coastal tree plantations can be destroy or get severely affect. With so much sea water coming inland, salination is another effect. Which not only mix the soil less fertile to support vegetation but also increases vulnerability to erosion, the impacts of climate change and food insecurity. For humans, on the other hand, fisheries, housing an infrastructure are the worst affect sectors.

Early Warning and Mitigation

1. Pacific Tsunami Warning Centre (PTWC)

The tsunami warning system in the Pacific, comprised of 26 participating International Member States, has the functions of monetary seismological and tidal stations throughout the Pacific basin to evaluate potentially tsunami genic earthquakes and disseminating tsunami warning information. The Pacific tsunami warning centre is the operational centre of the Pacific TWS. Located near Honolulu, Hawaii, PTWC provides tsunami warning information to national authorities in the Pacific Basin.

2. The Alaska Tsunami Warning Centre  (ATWC)

In Palmer, Alaska, serves as the regional Tsunami Warning Centre for Alaska, British Columbia, Washington, Oregon and California.

3. Indian Tsunami Early Warning System (ITEWS)

The Indian Tsunami Early Warning System has the responsibility to provide tsunami advisories Indian Mainland and Island regions. Acting as one of the regional Tsunami Advisory service Providers (RTSPs) for the Indian Ocean region. ITEWS also provide Tsunami advisories to the Indian Ocean Rim countries along with Australia and Indonesia.

Tsunami and its causes

Does Earthquakes actually trigger Tsunami

In order to confirm whether the earthquakes actually triggered a tsunami, it is essential to measure the change in water level as near to the fault zone with highly accuracy. There are two basic types of sea level gages: coastal tide gages and open ocean buoys.

Coastal Tide Gages

It is generally located at the land-sea interface, usually in locations somewhat protected from the heavy seas. Which are occasionally create by stone systems. Tide gages initially detect tsunami waves provide little advanced warning at the actual location of the gage, but can provide coastal residents where the waves have not get reached and indication that is tsunami does exist, it speed and its approximate strength.

Open Ocean Buoys

Its systems equipped with bottom pressure sensors are now a reliable technology. Which can provide advance warning to coastal areas that will be first impacted by a tsunami, before the waves reach them and nearby tide gages. Open Ocean buoys often provide a better forecast of the tsunami strength than tide gages at distant location.

Apart from technology we can also use natural barriers to mitigate the effect of tsunamis. Coral reefs act as natural breakwaters, providing a physical barrier that reduces the force of a wave. As it reaches the shore, by mangrove for forests act as natural shock absorber. They also soaking up destructive wave energy and buffering against coastal erosion.

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