The area where the earthquake occurred is where the Pacific Ocean floor is subducting or being pushed downwards under Alaska. Examples of tsunami originating at locations away from convergent boundaries include Storegga about 8, years ago, Grand Banks , Papa New Guinea The Grand Banks and Papua New Guinea tsunamis came from earthquakes which destabilised sediments, causing them to flow into the ocean and generate a tsunami.
They dissipated before traveling transoceanic distances. The cause of the Storegga sediment failure is unknown. Possibilities include an overloading of the sediments, an earthquake or a release of gas hydrates methane etc. In the s, it was discovered that larger tsunamis than had previously been believed possible could be caused by giant submarine landslides. These rapidly displace large water volumes, as energy transfers to the water at a rate faster than the water can absorb.
Their existence was confirmed in , when a giant landslide in Lituya Bay, Alaska, caused the highest wave ever recorded, which had a height of meters over feet.
The wave did not travel far, as it struck land almost immediately. Two people fishing in the bay were killed, but another boat amazingly managed to ride the wave. Another landslide-tsunami event occurred in when a massive landslide from Monte Toe went into the Vajont Dam in Italy. The resulting wave overtopped the m ft. Around 2, people died. Scientists named these waves mega tsunami. Scientists discovered that extremely large landslides from volcanic island collapses may be able to generate mega tsunamis that can cross oceans.
In general, landslides generate displacements mainly in the shallower parts of the coastline, and there is conjecture about the nature of truly large landslides that end in water. This is proven to lead to huge effect in closed bays and lakes, but an open oceanic landslide large enough to cause a tsunami across an ocean has not yet happened since before seismology has been a major area of scientific study, and only very rarely in human history.
Susceptible areas focus for now on the islands of Hawaii and La Palma in the Canary Islands, where large masses of relatively unconsolidated volcanic shield on slopes occur.
Considerable doubt exists about how loosely linked these slopes actually are. Some meteorological condition, especially deep depressions such as tropical cyclones, can generate a type of storm surge called ameteotsunami which raises water heights above normal levels, often suddenly at the shoreline.
In the case of deep tropical cyclones, this is due to very low atmospheric pressure and inward swirling winds causing an uplifted dome of water to form under and travel in tandem with the storm. There have been studies and at least one attempt to create tsunami waves as a tectonic weapon or whether human behavior may trigger tsunamis, e. There has been considerable speculation on the possibility of using nuclear weapons to cause tsunamis near to an enemy coastline. Even during World War II consideration of the idea using conventional explosives was explored.
Operation Cross roads fired two 20 kilotonnes of TNT 84 TJ bombs, one in the air and one underwater, above and below the shallow 50 m ft. Fired about 6 km 3. The smashing force of a wall of water travelling at high speed, and the destructive power of a large volume of water draining off the land and carrying a large amount of debris with it, even with waves that do not appear to be large.
While everyday wind waves have a wavelength from crest to crest of about meters ft. Such a wave travels at well over kilometers per hour mph , but owing to the enormous wavelength the wave oscillation at any given point takes 20 or 30 minutes to complete a cycle and has an amplitude of only about 1 meter 3.
This makes tsunamis difficult to detect over deep water, where ships are unable to feel their passage. As the tsunami approaches the coast and the waters become shallow, wave shoaling compresses the wave and its speed decreases below 80 kilometers per hour 50 mph. Its wavelength diminishes to less than 20 kilometers 12 mi and its amplitude grows enormously. Since the wave still has the same very long period, the tsunami may take minutes to reach full height.
Except for the very largest tsunamis, the approaching wave does not break, but rather appears like a fast-moving tidal bore. Open bays and coastlines adjacent to very deep water may shape the tsunami further into a step-like wave with a steep-breaking front. Run up is measured in meters above a reference sea level. A large tsunami may feature multiple waves arriving over a period of hours, with significant time between the wave crests. The first wave to reach the shore may not have the highest run up.
They are caused by earthquakes, landslides, volcanic explosions, glacier calvings, and bolides. An illustration of rhythmic drawback of surface water associated with a wave that follows a very large drawback may herald the arrival of very large wave. All waves have a positive and negative peak, i. In the case of a propagating wave like a tsunami, either may be the first to arrive.
If the first part to arrive at shore is the ridge, a massive breaking wave or sudden flooding will be the first effect noticed on land. However, if the first part to arrive is a trough, a drawback will occur as the shoreline recedes dramatically, exposing normally submerged areas.
Drawback can exceed hundreds of meters, and people unaware of the danger sometimes remain near the shore to satisfy their curiosity or to collect fish from the exposed seabed. A typical wave period for a damaging tsunami is about 12 minutes.
This means that if the drawback phase is the first part of the wave to arrive, the sea will recede, with areas well below sea level exposed after 3 minutes. During the next 6 minutes the tsunami wave trough builds into a ridge, and during this time the sea is filled in and destruction occurs on land.
During the next 6 minutes, the tsunami wave changes from a ridge to a trough, causing flood waters to drain and drawback to occur again. This may sweep victims and debris some distance from land. The process repeats as the next wave arrives. As with earthquakes, several attempts have been made to set up scales of tsunami intensity or magnitude to allow comparison between different events. The first scales used routinely to measure the intensity of tsunami were the Sieberg- Ambraseys scale, used in the Mediterranean Sea and the Imamura-Iida intensity scale, used in the Pacific Ocean.
The latter scale was modified by Soloviev, who calculated the Tsunami intensity I according to the formula: In , following the intensively studied tsunamis in and , a new 12 point scale was proposed, the Integrated Tsunami Intensity Scale ITIS , intended to match as closely as possible to the modified ESI and EMS earthquake intensity scales.
The first scale that genuinely calculated a magnitude for a tsunami, rather than an intensity at a particular location was the ML scale proposed by Murty and Loomis based on the potential energy. Difficulties in calculating the potential energy of the tsunami mean that this scale is rarely used. They must be large earthquakes that occur under or near the ocean, and create movement under the sea floor.
When these earthquakes occur at a submarine level, the vibrations cause the ocean water to ripple and move. And the bigger the earthquake.. A tsunami is, in essence, an enormous wave. Or, to be more specific, a series of giant waves.
They most often occur in the Pacific Ocean due to the amount of ocean trenches, mountain chains, and volcanoes that line the ocean floor. The problem with tsunamis is the fact that their effects are somewhat unpredictable. They can strike hundreds of kilometers away from where the initial earthquake took place. Generally, places such as Alaska, Japan, the Philippines, and the west coast of the United States are at the greatest risk. Tsunamis reach coastal areas the quickest, landing enormous waves on the shore in a manner that can tear buildings apart and sweep people and vehicles away.
They flood areas quickly and have an energy that is often equivocated to the energy from multiple blasts of TNT. This rise or fall in sea level is the initial formation of tsunami wave. Unlike surface waves that affect only a shallow amount of water, a tsunami stretches all the way to the sea floor, as rises to the land, so does the wave.
Arriving at shore, such waves can grow suddenly by dozens of feet. The satellite imaging did not provide a depth for the waves that hit ashore. In deep water, a tsunami can travel at km per hour. But in shallow water near coast, it get slower and water mass rises up to 50 meters. A tsunami is very much destructive. It can strip coasts of land, uproot trees, wipe out towns.
The records of tsunami deaths or disaster are generally not available as they are commonly fixed with earthquake deaths. In the year on 1st Nov. August 27, was another day of disaster. The eruptions from Krakatoa volcano fuelled a tsunami that drowned 36, in western Java and southern Sumatra.
- Australia & The World Tsunami essay The Boxing Day Tsunami in the Asian region was a devastating event for the Region and the World alike and will go down in history as one of the worst widespread events the World has seen in recent years.
Tsunami is generated when ocean floods shift vertically, usually due to an earthquake. When a shift in the ocean floor displaces the water above, the water body travels as a huge wave to regain equilibrium.
"The word Tsunami means 'harbor wave' which references the giant waves' ability to penetrate the protected harbors along Japan's coast" (Koenig, Science). Although these natural disasters are not as common as others, people need to be aware that Tsunamis can be very devastating and destructive, more so than tornados or other storms. Tsunami is commonly referred to as a sea monster. It cuts across the sea with an awesome speed. On reaching land, it sucks most of the water out of the harbor; then, the creature may rise more than feet tall and flatten whole villages.3/5(3).
Essay # 5. Causes of Tsunami: A tsunami is a large ocean wave that is caused by sudden motion on the ocean floor. This sudden motion could be an earthquake, a powerful volcanic eruption, or an underwater landslide. The impact of a large meteorite can also cause a tsunami. Essay on The Tsunami Disaster Words | 4 Pages. The Tsunami Disaster At GMT on 26 December , a magnitude earthquake ripped apart the seafloor off the coast of northwest Sumatra. Over years of accumulated stress was released in the second biggest earthquake in recorded history.