The impact of natural disasters

1. Most natural disasters may cause the destruction of drinking water supply system, which will be the first problem after the disaster, and often lead to the outbreak and epidemic of large-scale intestinal infectious diseases in the early days after the disaster.

2. Fuel shortage. In large-scale natural disasters, fuel shortage is also a common phenomenon, especially among victims trapped by floods. Fuel shortage first forced the victims to drink raw water and eat cold food, which led to the occurrence and spread of intestinal pollution.

3. Floods often pollute water bodies and lead to large-scale epidemics of some water-borne infectious diseases, such as schistosomiasis and leptospirosis. But the impact of flood on water pollution is twofold.

In large-scale floods, especially during travel, due to the dilution of floods, the incidence of such diseases shows no obvious signs of rising. However, when the flood began to fall, many small bodies of water were left in the waterlogged area. If these small water bodies are polluted, it will easily lead to the outbreak and epidemic of such diseases.

The extended data of natural disasters mainly include:

1, tornado

Tornado is the strongest vortex phenomenon in the atmosphere, which often occurs in thunderstorm weather in summer, especially in the afternoon and evening. Although the scope of influence is small, it is extremely destructive.

Tornadoes often pull up trees, overturn vehicles, destroy buildings and so on. They often destroy crops and tens of thousands of fruit trees instantly, interrupt traffic, collapse houses, and cause human and animal lives and economic losses.

2. Tsunami

Tsunami is a destructive wave caused by submarine earthquake, volcanic eruption, submarine landslide or meteorological change. The wave speed of tsunami is as high as 700 ~ 800 kilometers per hour, and it can cross the ocean in a few hours.

Wavelength can reach hundreds of kilometers, can spread thousands of kilometers, and energy loss is small; In the vast ocean, the wave height is less than one meter, but in the shallow sea coast, the wavelength becomes shorter and the wave height increases sharply, reaching tens of meters, forming a "water wall" with great energy.

Tsunami is mainly controlled by seabed topography, coastline geometry and wave characteristics. Roaring waves and ice walls repeat every few minutes or dozens of minutes, destroying banks, flooding land, taking away lives and property, which is extremely destructive. The global tsunami occurrence area is roughly consistent with the earthquake zone. There are about 260 recorded destructive tsunamis in the world, averaging about once every six or seven years.

Earthquakes and tsunamis around the Pacific Ocean account for about 80%. The earthquakes in the Japanese archipelago and its adjacent waters account for about 60% of the Pacific earthquakes and tsunamis, and Japan is the country suffering from the most severe earthquakes and tsunamis in the world.

3. Storm surge

Storm surge is a catastrophic natural phenomenon. Due to severe atmospheric disturbances, such as strong winds and sudden changes in air pressure (usually referring to disastrous weather systems such as typhoons and extratropical cyclones), when the sea water rises and falls abnormally and overlaps with astronomical tides (usually referring to tides), if this superposition happens to be the superposition of high surges formed by strong and low-pressure storm surges and astronomical climaxes, it will form stronger destructive power. It can also be called "storm increasing water", "storm tsunami", "meteorological tsunami" or "tidal wave".

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