Natural disasters are abnormal phenomena that occur in nature on which humans depend. The harm caused by natural disasters to human society is often shocking. Among them are earthquakes, volcanic eruptions, mudslides, tsunamis, Sudden disasters such as typhoons and floods; there are also gradual disasters such as land subsidence, land desertification, drought, and coastline changes that will gradually appear over a long period of time; there are also human activities such as changes in the ozone layer, water pollution, soil erosion, and acid rain. Environmental disasters. There are complex interrelationships between these natural disasters and environmental damage. It is an important task of the international community for humans to understand the occurrence and development of these disasters and minimize the harm they cause. ***Same topic.
Natural variations on the earth, including those induced by human activities, occur all the time and everywhere. When such variations bring harm to human society, they constitute natural disasters. . Because it brings varying degrees of damage to human production and life, including the relationship between humans and nature through labor, and the related relationships between humans, disasters are negative or damaging. Therefore, natural disasters are a manifestation of the contradiction between man and nature. They have both natural and social attributes and are one of the most severe challenges that mankind has faced in the past, present and future.
Major sudden natural disasters around the world include: droughts, floods, typhoons, storm surges, freeze damage, hailstorms, tsunamis, earthquakes, volcanoes, landslides, mudslides, forest fires, agricultural and forestry pests and diseases, etc.
Edit this paragraph The formation and development of natural disasters
All kinds of events that harm animals and plants are called disasters. Throughout human history, it can be seen that there are two main reasons for disasters: First, nature. Variation, and the second is human influence. Therefore, disasters that are mainly caused by natural variation are usually called natural disasters, such as earthquakes, storms, and tsunamis; disasters that are mainly caused by human influence are called man-made disasters, such as fires caused by humans. , traffic accidents, acid rain, etc.
The process of natural disasters may be long or short, slow or urgent. Some natural disasters will occur within a few days when the changes in disaster-causing factors exceed a certain intensity. Disasters manifest themselves within hours or even minutes or seconds, such as volcanic eruptions, earthquakes, floods, hurricanes, storm surges, hail, etc. Such disasters are called sudden natural disasters, droughts, crop and forest diseases, etc. Although pests, weeds, etc. generally take a few months to cause disasters, the formation and end of the disaster are still relatively fast and obvious, so they are also included in sudden natural disasters. There are also some natural disasters. When disaster-causing factors develop over a long period of time, disasters gradually appear, such as land desertification, soil erosion, environmental degradation, etc. Such disasters usually take several years or longer to develop, and are called slow-onset natural disasters. .
Many natural disasters, especially those with high levels and intensity, often trigger a series of other disasters to occur one after another. This phenomenon is called the earliest disaster chain. Disasters caused by disasters are called primary disasters; disasters induced by primary disasters are called secondary disasters. After the occurrence of natural disasters, the harmonious conditions for human survival are destroyed, which can also lead to a series of other disasters, which are generally called derivative disasters. For example, after a severe drought, there is an extreme shortage of surface and shallow fresh water, forcing people to drink deep groundwater with high fluoride content, which leads to fluoride disease. These are called derivative disasters.
Of course, the process of disasters is often very complicated. Sometimes a disaster can be caused by several disasters, or a disaster can cause several different disasters at the same time. At this time, the determination of the disaster type must be based on the leading cause of the disaster and its main manifestations.
Edit this paragraph Characteristics of natural disasters
Sudden and unpredictable. Natural disasters are often violent and extremely destructive. The duration may be long or short. Disasters involve many factors that can cause injuries and deaths, extensive property damage, and considerable chaos. The longer a disaster event lasts, the greater the threat to victims and the greater the impact of the event.
Another major characteristic that affects the severity of a disaster is whether people get enough warning.
Natural disasters have many important characteristics. They are sudden, powerful, uncontrollable, cause destruction and chaos, are usually short-lived, have a lowest point, and can sometimes be predicted.
Edit this paragraph about the impact of natural disasters
Disasters affect behavior and mental health in many ways:
⑴ Disasters can cause substantial trauma and Mental disorders;
⑵Most pain disappears within one or two years after the disaster, and people can adjust themselves;
⑶Chronic mental disorders caused by disasters are very rare;
⑷The overall impact of some disasters may be positive because it may increase social cohesion;
⑸Disasters disrupt organizations, families, and individual lives.
Natural disasters can cause stress, anxiety, depression, and other emotional and perceptual problems. The timing of the effects and why some people don't adapt sooner remains unknown. After floods, tornadoes, hurricanes, and other natural disasters, victims exhibit thoughts of thoughts, anxiety, depression, and other emotional problems that can last up to a year.
The lasting effects of an extreme disaster, called post-traumatic stress disorder, are persistent, unnecessary, uncontrollable thoughts about unrelated events after experiencing the trauma, and a strong avoidance of mentioning them. Event wishing, sleep disturbance, social withdrawal, and anxiety disorder with intense vigilance.
Edit this paragraph China’s natural disasters
Our country is the country with the most types of natural disasters in the world, among which there are seven major categories of natural disasters that have the greatest impact on our country.
1. Meteorological disasters
There are more than 20 kinds of meteorological disasters, mainly including the following types:
(1) Heavy rain: flash floods, river flooding, urban accumulation Water;
(2) Rain: waterlogging, waterlogging;
(3) Drought: drought in agriculture, forestry, and grasslands, water shortage in industry, cities, and rural areas;
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(4) Hot and dry winds: drought winds, foehn winds;
(5) High temperatures and heat waves: extreme heat, human diseases, burns, and ripening of crops;
(6) Tropical cyclones: strong winds, heavy rains, floods;
(7) Cold damage: damage to crops, livestock, and fruit trees due to strong cooling and low temperatures;
(8) Freezing damage: Frost, freezing damage to crops and livestock, freezing damage to water pipes and oil pipes;
(9) Freezing rain: freezing of wires, branches, and roads;
(10) Freezing: rivers, lakes, The sea surface freezes and the roads freeze after rain and snow;
(11) Snow damage: blizzard, snow; (12) Hail damage: destroy crops and houses;
(13) Wind damage: fallen trees, houses, overturned cars and boats;
(14) Tornado: local destructive disaster;
(15) Lightning: casualties caused by lightning strikes;
(16) Continuous rain (unpleasant rain): adverse to crop growth and development, food mildew, etc.;
(17) Dense fog: human diseases, traffic obstruction;
(18) Low-altitude wind shear: (aircraft) aviation crash;
(19) Acid rain: damage to crops, etc.
2. Marine disasters
Marine disasters mainly include the following types:
(1) Storm surge: including typhoon storm surge and temperate storm surge;
(2) Tsunami: divided into two types: remote tsunami and local tsunami;
(3) Waves: including wind waves, swells and nearshore waves, which are divided into three types in terms of their causes Wind waves, cyclone waves;
(4) Sea water;
(5) Red tide;
(6) Coastal disasters: such as coastal erosion, landslides, land Salinization, seawater pollution, etc.;
(7) The harm of El Ni?o.
3. Flood disasters
(1) Heavy rain disasters;
(2) Flash floods;
(3) Snowmelt floods;
(4) Ice flood;
(5) Dam burst flood;
(6) Debris flow and cement flow flood.
4. Earthquake disasters
(1) Tectonic earthquakes;
(2) Isolation earthquakes;
(3) Mine earthquakes ;
(4) Reservoir earthquakes, etc.;
5. Crop biological disasters
(1) Crop diseases: There are mainly more than 240 kinds of rice diseases, wheat diseases 50 kinds, more than 40 kinds of corn diseases,
more than 40 kinds of cotton diseases, and many diseases of soybeans, peanuts, hemp, etc.;
(2) Crop pests; mainly rice pests 252 kinds, more than 100 kinds of water-wheat insect pests, 52 kinds of corn insect pests, more than 300 kinds of cotton flower insect pests, and many other insect pests of various crops;
(3) Crops Weed damage: about 8,000 species;
(4) Rat damage.
6. Forest biological disasters
(1) Forest diseases: 2918 species;
(2) Forest pests: 5020 species;
(3) Forest rodent pests: more than 160 species.
The Comprehensive Research Group on Natural Disasters of the State Science and Technology Commission, State Planning Commission and State Economic and Trade Commission divides natural disasters into seven categories: meteorological disasters, marine disasters, flood disasters, geological disasters, earthquake disasters, crop biological disasters and forests Biological disasters and forest fires. However, the main disasters that are closely related to our daily life are:
1. Geological disasters
Both natural variability and man-made effects may lead to changes in the geological environment or geological bodies. When such When changes reach a certain level, consequences such as landslides, mudslides, ground decline, ground subsidence, rock expansion, sand and soil liquefaction, land freezing and thawing, soil salinization, land desertification, earthquakes, volcanoes, and geothermal damage will have serious consequences for human beings. and cause harm to society. This phenomenon is called a geohazard. Geological hazards also include derived hazards.
(1) Debris flow. Debris flow is a special torrent containing a large amount of sediment and rocks in mountainous valleys, triggered by heavy rain, melting ice and snow and other water sources.
The formation of debris flow: the following three conditions must be met at the same time: steep topography that is convenient for collecting water and materials; rich loose materials; and a large amount of water source in a short period of time.
Debris flows can be divided into three categories according to their material composition: debris flows are composed of a large amount of clay soil and sand and stones of different particle sizes; debris flows are mainly composed of clay soil and contain a small amount of clay particles, stones, The one with high viscosity and thick mud is called debris flow; the one composed of water and sand and stones of different sizes is called water-rock flow.
Hazards of debris flows: harm to residential areas; harm to roads and railways; harm to water conservancy and hydropower projects; harm to mines;
(2) Landslides. The phenomenon in which the rock mass on the landslide slides downward as a whole along a certain weak surface (or weak zone) under the action of gravity due to various reasons is called a landslide. Commonly known as "walking on the mountain", "crossing the mountain", "tuliu", etc.
Conditions for landslides: Only when the slope rock and soil are cut and separated into continuous parts by various structural planes can they have the conditions to slide downward.
The intensity of landslide activity: It is mainly related to the scale of the landslide, the speed of the landslide, the distance of the landslide, its accumulated potential energy and the generated kinetic energy.
The activity time of landslides: It is mainly related to various external factors that induce landslides, such as earthquakes, rainfall, freezing and thawing, tsunamis, storm surges and human activities.
(3) Collapse. Collapse, also called collapse, collapse or landslide, is a geological phenomenon in which rock mass on a steep slope suddenly breaks away from its parent body under the action of gravity, collapses, rolls, and accumulates at the foot of the slope (or ditch rock).
According to the composition of the collapse body material, collapses can be divided into two categories: soil collapse and rock collapse.
Time of collapse activity: Collapse generally occurs during heavy rains and long-term continuous rainfall or later; during intense earthquakes; during excavation at the foot of the slope or later; During the early stages of reservoir impoundment and river peak periods; after strong mechanical vibrations and large blasts.
Regional nature of collapses: Southwest China is the main area where collapses occur in my country.
(4) Ground sinking. Ground subsidence is a phenomenon of crustal deformation caused by long-term drought, lowering of groundwater levels, and excessive exploitation of groundwater.
(5) Earthquake. Earthquake is a very destructive natural disaster. In addition to landslides, ground fissures, and house collapses directly caused by earthquakes, they can also cause secondary disasters such as fires, floods, explosions, landslides, mudslides, poisonous gas spread, and plagues.
2. Floods and other disasters
(1) Rain and waterlogging. Rainfall refers to flash floods caused by large-scale heavy rains or extremely heavy rains. River water levels rise sharply and floods cause flooding of farmland, houses, people, livestock, and transportation facilities, as well as low-lying water that is difficult to drain. Waterlogging disasters resulting in reduced crop yields and loss of harvests.
(2) Flood. Flood disaster refers to the phenomenon of water flow escaping from waterways or artificial restrictions and endangering the safety of people's lives and property.
(3) Ice and flood disasters. Ice flood disaster is a phenomenon in which river water levels rise significantly due to the resistance of ice to water flow, causing disasters.
(4) Earthquake disaster. Earthquake floods refer to flood disasters caused by earthquake-induced landslides that block rivers or collapse dykes.
3. Wind disaster. When the wind force reaches enough to harm people's production activities, economic construction and daily life, it becomes a strong wind.
Hazards of strong winds: Hazardous strong winds mainly refer to typhoons, cold wave gales, thunderstorms and tornadoes.
According to the impact of strong winds on agricultural production, it can be summarized into several aspects such as mechanical damage, wind erosion, physiological hazards, and impact on agricultural and animal husbandry production activities. Typhoons are the most destructive among strong wind hazards.
4. Tropical cyclone disaster. A tropical cyclone is a cyclonic eddy that occurs in tropical or subtropical oceans.
Strong tropical cyclones are accompanied by strong winds, abalone, huge waves, and storm surges. They have a wide range of activities and are highly destructive. They are an important disastrous weather system. Our country is one of the few countries in the world severely affected by tropical cyclones.
5. Hail disaster. Hail is ice cubes or pellets that fall to the ground from powerful cumulonimbus clouds. According to the size of hail and the degree of damage, Kejiangbao is also divided into three levels: light hail damage, medium hail damage and heavy hail damage. Our country is one of the countries with more hail disasters in the world.
6. Marine disasters
(1) Storm surge. The interaction between cold air from high latitudes and tropical cyclones from the sea causes strong winds and huge waves to occur along the coast, thus forming a storm surge. The Western Pacific is the region that produces the most storm surges.
Types of storm surges: typhoon type; cold high pressure combined with Yellow Sea and Bohai Sea cyclone type; horizontal cold high pressure type; strong isolated Yellow Sea and Bohai Sea cyclone type; strong Mongolian low pressure type;
Storm Spatial distribution of tidal hazards. my country's storm surges spread all over the coast, but the main concentrated areas from north to south are: Laizhou Bay; Jiangsu Xiaoyanghe Estuary to Zhejiang Dehaimen; Wenzhou, Taizhou, Shacheng to the Minjiang Estuary; Guangdong Shantou to the Pearl River Estuary; Leizhou Peninsula The east coast and the northeastern coast of Hainan Island.
(2) Disastrous waves. Waves that cause disasters at sea are called disastrous waves.
The formation of disastrous waves: caused by typhoons, extratropical cyclones, cold waves and other weather systems and formed under the action of strong winds.
Disastrous waves are classified according to weather system types: cold high pressure type (also called cold wave type); typhoon type; cyclone type; cold high pressure and cyclone combination type.
(3) Sea ice. Sea ice is formed by freezing harmful water, including river ice and icebergs that flow into the ocean. Sea ice is one of the prominent marine hazards in polar seas and certain high latitude areas.
Disasters caused by sea ice. Push down offshore oil platforms, damage marine engineering facilities and waterway facilities, or crash ships to cause major maritime disasters; hinder the navigation of ships, damage propellers or hulls, and cause them to lose their navigation ability. Sea ice blocks the harbor, making it impossible for the port to operate normally or greatly increasing the cost of using icebreakers to break ice for navigation; it also prolongs the fishing moratorium and damages breeding facilities and sites, causing economic losses.
The main characteristics of sea ice disasters are: the Bohai Sea, northern Yellow Sea and coastal waters of the Liaodong Peninsula, which are prone to freezing in winter, as well as some bays of the Shandong Peninsula.
(4) Tsunami. Tsunamis are mainly marine disasters caused by violent earthquakes in Pacific coastal countries.
Conditions for the formation of tsunami: The source of the submarine earthquake that causes the tsunami is shallow, generally less than 20 kilometers to 50 kilometers; the magnitude is generally above 6.5 on the Richter scale; there must be large-scale vertical movement of the seafloor; occurrence The sea area for submarine earthquakes must have a certain water depth, especially for large tsunamis across the ocean. The water depth is generally more than 1,000 meters.
The hazards of tsunamis: The form of tsunami in coastal areas is that the sea water rises sharply, suddenly forming a "water wall" traveling towards the shore, and accompanied by a loud rumbling sound, it instantly invades the coastal land and engulfs fertile farmland and towns. , villages, and then the sea water suddenly recedes, or first recedes and then rises, sometimes repeated many times, causing huge losses to human life and property.
(5) Red tide. The concept of red tide: Red tide is caused by the sudden increase in value of some tiny phytoplankton, protozoa or bacteria in seawater under certain environmental conditions, causing the discoloration of seawater within a certain range and for a period of time.
The hazards of red tides: cause changes in the ocean, partially interrupt the marine food chain, and threaten the survival of marine organisms; some red tide organisms excrete mucus in vitro or decompose after death, which covers the filter feeding and breathing of marine animals, thereby causing He died of suffocation. Or the toxins contained in red tide organisms are ingested by marine animals, causing poisoning and death of fish, shrimp, shellfish, etc. Some of them can also cause poisoning and death of vertebrates and humans after eating them; in the following sections, we will introduce several common natural disasters that harm a large area, and also introduce some disaster prevention and relief measures.
7. Other disasters
In addition to earthquakes, floods, typhoons, plagues and other disasters that seriously affect our lives and even threaten our lives, we are also concerned about lightning, heavy fog, hail, etc. It is also necessary to continuously improve prevention awareness and strengthen prevention capabilities for other disasters.
Thunder and lightning
(1) Formation of thunder and lightning
Weather accompanied by thunder and lightning phenomena becomes a thunderstorm meteorologically. During a thunderstorm, when the potential difference between the clouds and the ground reaches a certain intensity, a discharge will occur. Lightning strikes the ground or hits certain objects, causing a lightning strike. According to research, the current intensity of a lightning strike can usually reach tens of thousands of amperes, and the temperature can reach 20,000 degrees Celsius. The degree of harm caused by such a strong current and high temperature can be imagined.
(2) Measures to prevent lightning strikes
1. During thunderstorms, people should stay indoors as much as possible, do not go out, and close doors and windows to prevent ball lightning from entering the room.
2. Try not to get close to doors, windows, stoves, heaters and other metal parts, and do not stand barefoot on the mud or cement floor. It is best to sit on a chair with non-conductive items under your feet.
3. Do not swim or row in the river to prevent lightning from hitting the human body through the water.
4. When encountering a thunderstorm in the wild, find a low-lying area or ditch to squat down as soon as possible. Do not take shelter under isolated trees, towers, or telephone poles.
5. Once someone is struck by lightning, rescue should be carried out in time. The rescue method is the same as the first aid for electric shock. Artificial respiration and extracorporeal heart massage should be carried out in time, and the person should be rushed to the hospital.
Anti-dense fog
When a large number of small water droplets or ice crystal particles are suspended in the near-low-level air, making people's vision blurred, and the horizontal distance between the parties drops to less than 1,000 meters. , is called fog.
Fog is divided into grades. When the visible distance is less than 1000 meters and more than 500 meters, it is called light fog; when the visible distance is less than 500 meters, it is called heavy fog; when the visible distance is less than 200 meters, it is called dense fog.
Protective measures against fog disasters:
1. Try not to go out. When you must go out, wear a mask to prevent inhalation of toxic gases.
2. Try to minimize activities in the fog and do not exercise in the fog.
3. Pedestrians should be careful when crossing the road and should see the passing vehicles clearly.
4. Slow down when driving vehicles and cars, obey the instructions of the traffic police, do not rush to get on the bus (boat), and do not crowd at the ferry when the ferry is suspended.
Hail
(1) The concept of hail
Hail is ice cubes or ice balls that fall to the ground from strong cumulonimbus clouds.
(2) Hail damage
According to the size of hail and the degree of damage, hail damage can be divided into three levels: light hail damage, medium hail damage and heavy hail damage. Hail causes considerable damage to crops, and my country is one of the countries with more hail disasters in the world.
(3) Geographic distribution characteristics of hail in my country
1. Hail-prone areas:
Hail-prone areas on the Qinghai-Tibet Plateau, hail-prone areas in the north, and hail-prone areas in the south district.
2. Hail-less areas:
Our country’s hail-less areas are mainly distributed in the great plains, great deserts, and great basins.
3. Time distribution characteristics of hail:
The season when hail falls in my country is mainly spring, summer and early autumn.
According to the seasonal changing characteristics of hail in various places, it can be divided into the following four types:
Multiple hail types in spring, multiple hail types in summer, multiple hail types in late spring and early summer, and double peaks type.
There are several main types of diurnal changes in hail: afternoon hail type; night hail type; midday hail type; multi-peak type, etc.
(4) Intensity characteristics of hail
Hail range size, hail size and weight, hail duration and accumulation thickness.
(5) Hail prediction and prevention
1. Hail is a disastrous weather that is difficult to predict. The meteorological station uses a large amount of real-time meteorological information such as weather radar, meteorological satellite monitoring and weather maps. Track and extrapolate forecasts for hail weather. There is also a lot of forecasting experience among the people, such as "hail is common in drought years", "steep winds are common in spring, hail is common in summer", "dark clouds are pagoda-shaped, with red clouds below, and hail is in front of you", etc. To sum up, there are six prediction methods:
(1) Feeling hot and cold; (2) Identifying the direction of the wind: "If the east wind does not blow, there will be no tide; if the south wind does not blow, there will be no hail"; (3) Look at the color of the clouds; (4) Listen to the thunder; (5) Recognize lightning; (6) Observe objects.
2. Hail defense:
(1) Avoid hail; (2) Prevent hail; (3) Resist hail; (4) Eliminate hail
Hail prevention is something that ordinary people can do, but the last three require specialized departments and personnel. Nowadays, with the advancement of technology, artificial hail elimination can achieve better results.
3. Response when hail comes:
(1) Upon learning of the weather forecast regarding hail, people, animals and outdoor items should be moved to a safe area.
(2) Try not to go out when hail strikes. When you have to go out, you should pay attention to protecting your head and face.
(3) If you are outdoors when hail strikes, you should immediately find a place to take shelter, preferably a sturdy building.
(4) If you are driving a car or in a car, you should immediately park the car in a place where you can avoid it, and do not move forward rashly to avoid unnecessary injury.
(5) Sometimes, hail will be accompanied by violent storms, so special attention should be paid to prevention and avoidance.