tsunami

 Definition of tsunami

     The name tsunami is taken from the Japanese language and means harbor wave, and the idiomatic tsunami wave is a large, violent, very large wave caused by the movement of large volumes of sea water as a result of a sudden phenomenon or event.  Like an earthquake, a tsunami can be compared to a giant wave forming in a pond. These waves are different from normal waves caused by wind motion and have nothing to do with some motion-induced phenomena. Therefore, experts do not like to use the term tsunami as tsunami.

     Tidal phenomena do not affect the generation of tsunamis, but they do become an influencing factor when they reach coastal areas. When a tsunami occurs during high tide, the intensity of the tsunami increases and can inundate more land. Tsunamis have tremendous strength and speed, as waves can travel at speeds of up to 804 kilometers during a tsunami. An example reflecting these wave velocities in AD 1960 is the tsunami that reached the coast of Japan from the coast of Chile. 22 hours and 15 hours to Hawaii.

     Cause of Tsunami

     There are various causes of tsunamis. These causes generate waves that are generated when large amounts of water are pushed out into the oceans and oceans, and the likelihood of tsunami generation varies from region to region depending on the nature of the plates that make up the region.  The area around the Pacific Basin is considered the most vulnerable area, and the reasons that may lead to the occurrence of this phenomenon are:

Earthquakes: Earthquakes are the main cause of most tsunamis around the world. As a result of the tectonic plates in the crust moving towards each other, when an earthquake occurs on the ocean floor, a large amount of water rises upwards, sometimes generating a tsunami.  Not all earthquakes that occur lead to tsunamis, and when they do, they do not necessarily cause catastrophic damage or have a large impact. Scientists have shown that only one in 15 tsunamis causes significant destruction and damage. caused many people to die. The area reached by the tsunami was Japanese territory as it reached 10 kilometers inland, and this tsunami wave rose to about 40 meters.

Volcanoes: Volcanic eruptions are one source of tsunamis. An example is Krakatoa, which erupted in Indonesia in 1883. 120,000 people.

Landslides: Undersea and ocean landslides can cause tsunamis, and the 1958 tsunami at Lituya Bay, Alaska is an example of a tsunami caused by a large landslide rising high over the bay. In addition to huge waves.  Tsunamis can reach over 520 meters on both sides and reach heights of up to 30 meters, and tsunamis are not limited to landslides, but can occur as a result of tsunamis. Part of the glacier collapsed underwater.

Tsunami characteristics

     Tsunami strength and impact on coastal areas depend on various characteristics of coastal areas. It can have a small impact in some areas, but can be very devastating in others. It has frequency, and what is known as velocity. These concepts and their respective characteristics are described below.

     Wavelength: Wavelength is defined as the distance between two points of similarity between two consecutive waves. Normal ocean waves have wavelengths in the range of 100 to 200 meters, but tsunamis have much longer wavelengths as they can reach 500 kilometers.

     Wave Height: Wave height refers to the distance between the trough and crest of a wave.

     Wave Amplitude: Describes the distance between the bottom of the wave and a fixed waterline. The amplitude of a tsunami wave varies with water depth, and the wave amplitude is usually equal to half its height.

     Wave Frequency: Wave frequency is defined as the time required for a wave to repeat. A normal ocean wave takes 5-20 seconds to reappear, while a tsunami takes 1-10 minutes. It takes 2 hours to repeat.

Wave speed: The speed at which waves move, which can reach 950 km/h compared to jet aircraft, but the normal speed of waves in the ocean is about 90 km/h. Tsunami Risk Tsunami events can pose many risks and damages to people, property and others. Debris carried by waves can become projectiles, collisions with this debris can lead to the collapse of coastal infrastructure, and tsunamis can disrupt and destroy gas and electricity supplies.  This can lead to fires and tsunamis can threaten people's food security by destroying crops.

     Beware of tsunami

     People on the beach can predict an upcoming tsunami when they notice possible anomalies on the beach. When a strong roar similar to that of an airplane or train is heard, when the sea level drops abnormally, when the water rises like a wall, or when a strong earthquake is felt, a tsunami occurs in coastal areas where people live.  Regarding tsunami prediction by scientists and experts, there are many systems that can be used to predict the occurrence of tsunamis and these systems are:

Tidal measurement

     This gauge is known as a tide gauge and this system is used to measure sea level and tide level. These sensors emit sound pulses inside the tube, and the water sends these sound pulses back to the sensor after passing some distance through the tube. Sea level can be measured by calculating the time it takes for an acoustic pulse to be emitted and bounce back, and the system measures changes in water level height of up to 1 mm.

 satellite

Tsunami waves can be predicted by satellite technology, which relies on the principle of knowing the height of the water level by dropping electromagnetic pulses from a satellite onto the ocean or sea surface and measuring the time it takes for the electromagnetic pulses to arrive. . The problem with using this system is that satellites are used to cover many areas. In some areas, water levels may only be measured once a month.

 arrow system

     DART stands for Deep Ocean Assessment and Reporting of Tsunami Waves, and the system works through a series of deep-sea stations. These stations measure seafloor pressure and transmit the results to floating buoys, which in turn transmit the results to specialized tsunami warning centers. It was initiated by the National Oceanic and Atmospheric Administration (NOAA).

most famous tsunami

     There have been many devastating tsunamis throughout history, from ancient times to the present day. The tsunami that occurred in AD 365 impacted various parts of the Mediterranean, stretching from the western Aegean islands to the coast of what is now Spain, and even to the coast of Alexandria. Egypt, and killed dozens of people. Thousands of people and many crops were destroyed.

     The Krakatoa volcano eruption in 1883 AD flooded the island of Rakata and triggered a huge tsunami that reached many islands in the East Indies. It reached Hawaii and then Japan, killing 183 people in both. region.

     This is considered one of the largest tsunami disasters in 2004 AD. Its devastating wave reached the eastern coasts of Sri Lanka, India, Thailand, Maldives, Somalia, Malaysia, Myanmar and Bangladesh, in addition to the Indonesian island of Sumatra, near where the quake struck, creating a massive tsunami. , and this disaster claimed the lives of more than 200,000 people, and the world continued to witness devastating waves.Besides the tsunami, we also witnessed massive destruction caused by tsunamis caused by undersea earthquakes, and nuclear power plants. A certain power also damaged the Fukushima power plant.

     What to do if a tsunami hits

     A person may be in an area with a higher tsunami risk than others, and if one is in that area and a tsunami occurs, there are many steps and measures that can be taken to escape the danger of this disaster, Measures include:

•      This procedure should also be followed if strong earthquakes occur in these areas and move to high coastal areas instead of low coastal areas. A tsunami may occur.

•      Until the competent authorities make a decision to eliminate the risk of tsunamis that may occur several times in a row, please stay away from dangerous areas.

• Watch out for signs that may indicate a tsunami, such as a significant drop or rise in water levels. At first glance, it looks like a small tsunami, but in the coastal areas, the tsunami reaches several kilometers.

•      The Pacific coastal area is prone to tsunami damage and caution is required. However, some areas are not dangerous.

•      Do not go to sea during a tsunami. More tsunamis can cross than people flee. Cooperate with authorities involved in disaster management.

• Building exits in low coastal areas. Being in such a building can be deadly, so if you can't get out or reach high places, you can hide in the upper floors of a solid cement building.

• It is recommended to go to depths of 180 meters or more. If the boat or boat has people on board during a tsunami, leave the boat or boat and head to the next location if the weather conditions do not allow it. It is recommended to go to higher areas.

• Tsunamis can create many waves and swells for some time, so do not return your boat or motorboat to shore before it is safe to do so.

•      Always follow the media and weather news for any news that may be announced about the tsunami outbreak.