What is a tsunami?

A tsunami is a powerfully destructive wave. The waves caused by this wave movement are turbulent and turbulent, and the waves they roll up can reach tens of meters in height. This "water wall" contains a huge amount of energy and is invincible after rushing onto land, often causing serious damage to life and property. The waves formed by the Chilean tsunami traveled tens of thousands of kilometers without losing strength, which shows its huge power.

A tsunami is a catastrophic wave, usually caused by an undersea earthquake with a source within 50 kilometers under the sea and a magnitude of 6.5 or above on the Richter scale. Tsunamis can also be caused by underwater or coastal landslides or volcanic eruptions. After a shock, shock waves spread over great distances in ever-expanding circles on the sea surface, just like the waves produced by a pebble dropped into a shallow pool. The wavelength of a tsunami is greater than the maximum depth of the ocean, and its orbital motion is not greatly hindered near the seafloor. The wave can propagate regardless of the depth of the ocean.

Shortly after the violent shaking, huge waves roared, crossing the coastline and fields with overwhelming force, rapidly attacking the cities and villages on the shore. In an instant, people disappeared in the huge waves. All the facilities and collapsed buildings in the port were swept away by the violent waves. Afterwards, the beach was in a mess, with broken wood and dead bodies everywhere. Earthquakes and tsunamis bring huge disasters to mankind. At present, humans can only prevent or reduce the losses caused by sudden disasters such as earthquakes, volcanoes, and tsunamis through prediction and observation, but they cannot yet control their occurrence.

A tsunami is a powerfully destructive wave. The waves caused by this wave movement are turbulent and surging, and the waves they roll up can reach tens of meters in height. This "water wall" contains a huge amount of energy and is invincible after rushing onto land, often causing serious damage to life and property. The waves formed by the Chilean tsunami traveled tens of thousands of kilometers without losing strength, which shows its huge power.

A tsunami is a powerfully destructive wave. A tsunami is a catastrophic wave, usually caused by an undersea earthquake with a source within 50 kilometers under the sea and a magnitude of 6.5 or above on the Richter scale. The waves caused by this wave movement are turbulent and turbulent. The waves it stirs up can reach tens of meters in height. This "water wall" contains a huge amount of energy and is invincible after rushing onto land, often seriously destroying lives and causing property damage. The waves formed by the Chilean tsunami traveled tens of thousands of kilometers without losing strength, which shows its huge power.

They are very different from the waves or tides generated by the wind. The breeze blows across the ocean, creating relatively short waves. The resulting water flow is limited to shallow water bodies. Strong winds can roll up waves with a height of more than 3 meters in the vast ocean, but they cannot shake the water in the depths. Tides sweep across the world twice a day. The currents it generates can penetrate deep into the bottom of the ocean like tsunamis, but tsunamis are not caused by the gravity of the moon or the sun. They are generated by underwater earthquakes, or by volcanic eruptions, meteorite impacts, or underwater landslides. Tsunami waves can reach speeds of more than 700 kilometers per hour in the deep ocean and can easily keep pace with a Boeing 747 aircraft. Although it is fast. But tsunamis are not dangerous in deep water. A single wave of less than a few meters can be more than 750 kilometers long in the open ocean. The tilt of the sea surface caused by this effect is so subtle that such waves usually occur inadvertently in deep water. It's over. Tsunamis move silently and imperceptibly through the ocean, but if unexpectedly in shallow water they can reach catastrophic heights.

Howling is a powerful and destructive wave. Tsunamis can be caused by underwater earthquakes, volcanic eruptions, or geodetic activity such as underwater collapses and landslides.

When an earthquake occurs, the seafloor strata fracture and some strata rise or sink suddenly, causing the entire water layer from the seafloor to the sea surface to "tremble" violently. This "jitter" is very different from the waves you usually see. Waves generally only rise and fall near the sea surface, and the depth involved is not large. The amplitude of the waves attenuates quickly with the water depth. The "shaking" of seawater caused by earthquakes is the fluctuation of the entire water body from the bottom of the sea to the sea surface, and the energy contained in it is amazing.

The rough waves set off by tsunamis can reach heights ranging from more than 10 meters to dozens of meters, forming a "water wall". In addition, tsunamis have large wavelengths and can travel thousands of kilometers with very little energy loss. Due to the above reasons, if a tsunami reaches the shore, the "water wall" will rush onto the land, posing a serious threat to human life and property.

There are two types of earthquakes and tsunamis

Tsunamis can be divided into 4 types. That is, storm surges caused by meteorological changes, volcanic tsunamis caused by volcanic eruptions, landslide tsunamis caused by submarine landslides, and earthquake tsunamis caused by submarine earthquakes. According to materials provided by the China Earthquake Administration, earthquakes and tsunamis are when an earthquake occurs on the seafloor, and the seafloor terrain rises and falls sharply, causing strong disturbances in the seawater. There are two types of mechanisms: "down" tsunamis and "uplift" tsunamis.

"Descent" tsunami: Certain tectonic earthquakes cause a large-scale sharp decline in the seafloor crust. The seawater first rushes into the suddenly displaced and sunken space, and a large-scale accumulation of seawater occurs above it. When the inrush occurs, After the advancing seawater encounters resistance on the seabed, it turns back to the sea surface to generate compression waves, forming long waves and large waves, which spread and spread around. The tsunami caused by this downward movement of the seafloor crust first manifests as an abnormal low tide phenomenon on the coast. The 1960 Chile earthquake and tsunami fell into this category.

"Uplift type" tsunami: Certain tectonic earthquakes cause a large-scale sharp rise in the seafloor crust. Seawater also rises along with the uplift area, and large-scale seawater accumulation occurs above the uplift area. Under the influence of gravity, Under the pressure, seawater must maintain an equipotential surface to achieve relative equilibrium, so seawater spreads from the wave source area to the surroundings, forming turbulent waves. The tsunami wave formed by this uplifted seafloor crustal movement first appears as an abnormal high tide on the coast. On May 26, 1983, the tsunami caused by the 7.7-magnitude earthquake in the Sea of ??Japan was of this type