What are the main natural disasters?
1. Tornado
A tornado is the strongest vortex in the atmosphere. It often occurs during thunderstorms in summer, especially in the afternoon and evening. Small, but extremely destructive.
Wherever a tornado passes, phenomena such as uprooting trees, overturning vehicles, and destroying buildings often occur. It often destroys patches of crops and tens of thousands of fruit trees in an instant, interrupts traffic, and collapses houses. , human and animal life and economic losses were suffered.
2. Tsunami
A tsunami is a destructive wave produced by submarine earthquakes, volcanic eruptions, submarine landslides or meteorological changes. The wave speed of a tsunami is as high as 700 to 800 kilometers per hour. It can cross the ocean within a few hours; the wavelength can reach hundreds of kilometers and can travel thousands of kilometers with very little energy loss; in the vast ocean, the wave height is less than one meter, but when it reaches the shallow waters of the coast, the wavelength is shortened and the wave height is It rises sharply, reaching tens of meters, forming a "water wall" containing huge energy.
Tsunami is mainly controlled by the submarine topography, coastline geometry and wave characteristics. The roaring waves and ice walls repeat every few minutes or tens of minutes, destroying the embankments, flooding the land, and taking away lives and property. Extremely destructive. Tsunami-generating areas around the world roughly coincide with earthquake zones. There are about 260 recorded destructive tsunamis around the world, occurring once every six or seven years on average.
About 80% of earthquakes and tsunamis occur in the Pacific Rim. Earthquakes in the Japanese archipelago and nearby waters account for about 60% of Pacific earthquakes and tsunamis. Japan is the country that suffers the most from earthquakes and tsunamis in the world.
3. Storm surge
Storm surge (Storm Tide) is a disastrous natural phenomenon. The situation occurs when severe atmospheric disturbances, such as strong winds and sudden changes in air pressure (usually referred to disastrous weather systems such as typhoons and extratropical cyclones) cause abnormal rise and fall of sea water, and are superimposed with astronomical tides (usually referred to as tides). If this superposition happens to be The superposition of high swells formed by strong low-pressure storm surges and astronomical high tides will create stronger destructive power. It can also be called "storm water increase", "storm tsunami", "meteorological tsunami" or "wind tide".
4. Flash floods
Flash floods refer to sudden floods that occur in mountainous valleys. Flash floods are sudden, with concentrated water flow, high velocity, and strong erosion and destructive power. The water flow carries sediment and even stones, which often cause localized floods. They are generally divided into heavy rain flash floods, snowmelt flash floods, glacier flash floods, etc. By improving flood control standards, adjusting human activity patterns, and enhancing people's awareness of disaster prevention and avoidance in mountainous areas, we can achieve the purpose of reducing the frequency of flash flood disasters or mitigating their harm.
In the planning of flash flood prevention and control, it is advisable to combine engineering measures and non-engineering measures in the short term, and plant measures in the long term. On October 27, 2006, the State Council officially approved the National Flash Flood Disaster Prevention and Control Planning Report. This is China’s first special plan for the prevention and control of flash flood disasters jointly organized by multiple departments of the State Council.
5. Debris flow
Deadslides refer to landslides caused by heavy rain, snow or other natural disasters in mountainous areas or other areas with deep ravines and steep terrain and carry a large amount of mud. A special torrent of sand and rocks. Debris flows are characterized by suddenness, fast flow speed, large flow, large material capacity and strong destructive power. Debris flows often destroy transportation facilities such as roads and railways and even villages and towns, causing huge losses.