NATURAL DISASTERS: CHARACTERISTICS, CAUSES, TYPES, CONSEQUENCES - ENVIRONMENT - 2025

Natural disasters are events that negatively impact life and human beings in general, caused by phenomena originated without human intervention. In many cases, the human being has responsibility for the impact of the consequences of bad technological practices, omissions or bad planning.

The causes of natural disasters are multiple, according to the type of natural phenomenon that causes the disaster in question. In general, natural disasters are caused by climatic phenomena, geomorphological processes, biological factors or by spatial phenomena.

Consequences of an earthquake. Source: Leggi il Firenzepost These phenomena pass into the category of natural disaster when they reach extreme levels. In addition to occurring in conditions conducive to drastically affect the human being or life in general.

Among the natural disasters of climatic origin are tropical cyclones, floods, droughts, forest fires, tornadoes, waves of heat and cold. While geomorphological processes cause volcanic eruptions, earthquakes and tsunamis.

For their part, biological factors cause epidemic diseases that in many cases have high levels of mortality. Finally, space disasters are less frequent, including meteorite and asteroid impacts.

Characteristics of natural disasters

They cause negative consequences

A disaster is an event that occurs in a relatively short time, generally not expected, that causes a negative impact on life. Disasters can occur naturally, be caused by human action, or happen by a combination of natural and human factors.

An event becomes a disaster when it negatively affects the human being, either directly or indirectly.

They are natural

An event is considered of natural origin when it occurs without human intervention. It is an anthropic notion where the human being is placed as an entity external to nature.

In this way, the human being differentiates his actions and the consequences derived from the rest of the events that occur in the Universe.

Causes

Natural disasters originate from processes that involve terrestrial dynamics and that can be climatic, geomorphological, biological, as well as spatial phenomena.

Climatic causes

The variations of the atmospheric time in terms of temperature, precipitations, atmospheric pressure and winds, determine a great part of natural disasters. This type of cause causes phenomena such as hurricanes, hailstorms, electrical storms, sand storms, tornadoes and waves of cold or heat.

Likewise, they generate floods when the rains are excessive and forest fires when the drought is extreme.

In many cases, natural disasters occur from a combination of these general causes. For example, a flood, a landslide or an avalanche is produced by a combination of climatic and geomorphological causes (relief, land movements).

Geomorphological causes

The movements of the tectonic plates and the dynamics of the Earth's crust and mantle cause earthquakes, volcanic eruptions and tsunamis. Likewise, the characteristics of the land relief combined with climatic factors produce avalanches and massive landslides.

Biological causes

Ecological imbalances cause population growth of some pathogenic organisms (viruses, bacteria) or their vectors, causing epidemics. Under favorable conditions determined by high human concentrations and weaknesses in public health controls, pandemics can be generated.

Causes of outer space

Meteorites and asteroids entering the Earth's atmosphere from outer space can also cause natural disasters.

Types of natural disasters

Any phenomenon that affects the Earth and reaches extreme levels that alter its regularity can turn into a natural disaster. In this sense, the types of natural disasters that occur periodically with greater or less regularity are varied.

Avalanches

It is a large mass of snow on steep terrain that, due to the effect of gravity, tumultuously falls down the slope. This occurs when snow accumulates and its weight reaches a critical point in relation to the slope of the terrain.

If it occurs in areas occupied or traveled by human beings, it becomes a natural disaster.

Tropical cyclone

Tropical cyclone. Source: National Aeronautics and Space Administration (NASA) It is a large-scale rotating tropical storm that includes heavy rainfall and high-speed winds. The storm can cover a diameter of up to 2,000 km with winds exceeding 200 km / h. Strong winds cause storm surges, floods, destroy structures, topple trees and kill.

Another name for tropical cyclones is hurricanes in the North Atlantic, the Caribbean and the Northeast Pacific. While in the Northwest Pacific they are called typhoons and in the Indian Ocean and Southeast Pacific simply cyclones.

Landslides or landslides

Similar to the avalanche, in this case it is the detachment of land masses on steep slopes. Generally it occurs due to intense and prolonged rainfall that saturates the land causing the soil to detach en masse.

They can also occur from tremors or earthquakes. In any case, the mass of earth or mud rushes down the slope dragging vegetation and everything in its path.

Epidemics and pandemics

Infectious-contagious diseases are one of the worst natural disasters, since they affect large numbers of people. As they spread, they become epidemics and even pandemics when they reach several countries. In some cases these diseases cause the death of large numbers of people.

Many non-biological natural disasters result in the proliferation of pests and diseases, triggering epidemics, particularly floods and landslides.

Volcanic eruptions

It is the massive expulsion of magma, ash and gases from the Earth's mantle into the atmosphere. The earth's surface is broken and the molten material found in the mantle comes out, in some cases in an explosive form. The magma derives in a flow that covers the earth's surface (lava) and the ash and gases permeate the air.

The lava flow reaches up to 1,200 ºC and burns everything in its path, while the ash and gases cause suffocation. Volcanic explosions spew ash and stones that burn and strike, cover crops and lose crops.

Hailstorms

It consists of the precipitation of ice stones of 5 to 50 mm in diameter (even up to 20 cm), which when impacting can cause considerable damage. These masses of ice can weigh up to 1 kg and reach speeds of 180 meters per second.

Meteorite and comet impacts

A meteorite is a celestial body smaller than 50 m in diameter that penetrates the Earth's atmosphere and impacts the surface. While an asteroid is a body with a diameter greater than 50 m that travels through space and can impact the Earth.

This is one of the most fearsome natural disasters because depending on the diameter, its impact can be equivalent to the explosion of several nuclear bombs.

The impact of a large diameter asteroid destroys large areas, destroying everything and driving large amounts of dust into the atmosphere. This dust can reach large areas in its atmospheric circulation and reduce the penetration of solar radiation by altering the earth's temperature.

Forest fires

Forest fire. Source: Cameron Strandberg from Rocky Mountain House, Alberta, Canada Although in a significant number of cases forest fires are caused by human actions, many others occur naturally. Extreme drought conditions can cause the spontaneous ignition of dry vegetation, starting the fire, being spread by the wind.

Forest fires destroy vegetation and kill animals and humans, due to fire, high temperatures and smoke. On the other hand, they are an important source of CO2 release into the atmosphere, contributing to global warming.

Floods

The overflows of large rivers, lakes and other natural water bodies are natural disasters of great magnitude. The waters invade areas outside their ordinary natural channel, affecting wildlife and humans.

The force of the water destroys infrastructure, uproots trees and carries animals and people that can die from drowning or impacts from floating objects.

Droughts

The absence of rain and the consequent high temperatures cause extreme droughts that directly affect life. Crops are lost, animals die, and humans are often forced to leave, go hungry and thirsty, and even die.

The drought generates the conditions for the desertification of soils, thus losing sources of agricultural sustenance. Similarly, sources of drinking water are lost as evapotranspiration increases and aquifers do not recharge.

Earthquakes

They are a type of natural disaster very feared for being unpredictable and its consequences. During its occurrence, movements occur in the earth's crust caused by plate tectonics and generate cracks as well as massive horizontal and vertical displacements.

This collapses structures, causes explosions of domestic gas lines, ruptures of water pipes, dams and other accidents. High-magnitude earthquakes cause large numbers of deaths and injuries, leaving many people without homes, communication routes and basic services.

Sand and dust storms

These natural phenomena occur in arid and semi-arid areas, especially in deserts, caused by strong winds acting on a sandy substrate. These winds move the sand forming clouds that impact on objects and living beings causing suffocation and abrasion.

Suspended particles

Sand and dust storms are sources of suspended particles in the atmosphere, even at high levels in the troposphere. These particles are one of the most troublesome air pollutants because they cause serious respiratory problems.

Simoom

They are sandstorms of high intensity, with dry winds with temperatures of up to 54 ºC, which displace immense clouds of sand. They occur in the Sahara desert and the deserts of Arabia, Palestine, Jordan and Syria.

Electric storms

Electric storm. Source: Chessbotija They are caused by the accumulation of updrafts of hot and humid air in an unstable atmosphere. Lightning bolts are formed which are static electric discharges and can be accompanied by rain, strong winds and even hail.

If electric shocks reach the ground, a lightning strike is produced that can cause fires, destroy structures, trees or even kill people or animals.

Tornadoes

Twister. Source: Justin1569 at English Wikipedia It is a cloud extension that forms a cone of air in revolution, whose lower end touches the ground, moving erratically. These phenomena can exceptionally consist of winds of more than 400 km / h and be up to 2 km wide.

Tornadoes destroy infrastructure, detach trees, damage roads and all kinds of facilities, and threaten the lives of animals and people. For example, the level 5 tornado (highest on the scale) called the Tristate of 1925 in the USA, caused the death of more than 600 people.

Tsunamis or tidal waves

They consist of the formation of large waves that move at high speed and when they impact on the coasts they can cause great disasters due to the impact and flooding. These waves are generated as a consequence of the vertical movements of the seabed caused by underwater earthquakes (tidal waves).

They can also occur from underwater volcanic eruptions or when large masses of rocks or ice fall into bodies of water from a great height.

Heat wave

They consist of an increase in the regular temperature of a region above the normal average for the place and period of the year. These high temperatures are maintained for a relatively long period of several days or weeks.

Heat waves are a natural disaster that affects human health by producing heat strokes or thermal shock, generating acute dehydration. This dehydration compromises the function of various organs and can cause death.

In addition, the extreme drought it causes affects natural vegetation and crops, as well as drinking water reserves. They also contribute to the increase in forest fires.

Cold wave

Cold waves are periods with persistent very low temperatures, caused by polar or continental cold air fronts. Extreme low temperatures affect wildlife, agricultural crops, roads, and humans.

In cases of especially susceptible people (the elderly, children, the sick), without adequate heating can cause death.

Consequences

Each type of natural disaster has its own characteristics and has particular consequences. However, they generally imply loss of human life, economic loss and damage to the environment and biodiversity.

Loss of human life

Larger natural disasters generally cause fatalities, which in some cases can be very numerous. In January 2020 an earthquake in Turkey killed 29 people, and 100 years ago the Spanish flu killed more than 50 million.

Social imbalance

In addition to the serious loss of life, natural disasters cause a deterioration in the quality of life of the survivors. For example, there is the displacement of populations that are forced to leave their living area, having lost all their belongings and housing.

Economic losses

Most natural disasters imply great economic losses due to the destruction of infrastructure, roads and communication systems. Equipment, vehicles are destroyed or large areas of crops and forest resources are lost.

Environmental alterations and loss of biodiversity

The ecological balance of an area where a natural disaster occurs can be seriously altered. In some cases they involve the loss of large areas of forests, with the loss of populations of plants and animals.

Examples of natural disasters that have occurred throughout history

The asteroid in the Gulf of Mexico

A natural disaster is generally considered to have occurred when people are directly affected, although there are exceptions. This is the case of a natural disaster that occurred millions of years before the appearance of our species, the impact of the Chicxulub asteroid.

This asteroid impacted what is now the Gulf of Mexico near Yucatán in the late Cretaceous, about 65 million years ago. This caused the disappearance of numerous species, including dinosaurs, which is considered a mass extinction.

The eruption of Mount Tambora (Indonesia, 1815)

Mount Tambora is located north of the island of Sunbawa in Indonesia, forming the Sanggar Peninsula. This volcano caused the largest volcanic eruption reported by humans, causing 71 thousand deaths.

Most of the deaths were not a direct cause of the eruption, but rather due to the epidemics and hunger that followed.

The Spanish flu of 1918

In the midst of World War I, a viral disease pandemic occurred that killed 50 to 100 million people. Given the precarious conditions and overcrowding caused by the war, the virus spread widely and rapidly.

The overflow of the Yellow River (China. 1931)

This flood was of great proportions and estimates indicate a death toll of more than 3,000,000. These deaths include those caused by the direct effects of the flood and those caused later by famine and unleashed epidemics.

The Dust Bowl (USA, 1932-1939)

The name of this natural disaster, Dust Bowl, means bowl of dust and it was an intense and prolonged drought that caused dust storms. It happened in the great prairies region of North America, in the center and north, and caused the loss of crops.

This led to the bankruptcy of small farmers, hunger and the displacement of more than three million people. It is considered that this natural disaster influenced the worsening of the Great Depression in the United States during the 1930s (in the 20th century) that affected the world economy.

Cyclone Bhola (Bangladesh, 1970) and Hurricane Katrina (USA, 2005)

Cyclone Bhola, recognized as the one that has caused the most deaths in history, reached the number of at least 500,000 deaths. Some sources speak of more than 1 million deaths caused by this cyclone and its aftermath.

New Orleans flooded by Hurricane Katrina. Source: AP Photo / US Coast Guard, Petty Officer 2nd Class Kyle Niemi While Hurricane Katrina hit New Orleans (USA) in 2005, causing 2,541 deaths and losses in the order of 89.6 billion dollars.

The Vargas landslide (Venezuela, 1999)

The Vargas landslide, known as the Vargas Tragedy, has been classified as the deadliest mudslide in history. About 30,000 people died in this natural disaster and thousands were displaced from the region. This is due to the avalanche of mud and rocks and floods that swept the coasts of Vargas state in the Venezuelan Caribbean.

The cause was the fall of intense rains that saturated the soils on the high slopes of the Cordillera de la Costa. Just as they increased the flow of the rivers that flow into the sea. This caused the massive detachment of soil and vegetation, dragging everything in its path, as well as flooding.

The Sumatra-Andaman Tsunami (Indian Ocean, 2004)

Aftermath of the tsunami in Sumatra in 2004. Source: US Navy photo by Photographer's Mate 2nd Class Philip A. McDaniel An underwater earthquake in December 2004 in the Indian Ocean generated several tsunamis that reached various shores. The giant waves hit and flooded Indonesia, Malaysia, Sri Lanka, India and Thailand, the most serious case being Sumatra (Indonesia), leaving at least 230,000 deaths.

The heat wave in Russia in 2010

In 2010 Russia suffered the worst heat wave in its history, reaching temperatures of up to 40 ° C. These temperature levels exceeded the records of 150-year averages. It is said that this natural disaster caused the death of more than 50 thousand people, loss of crops and a large number of forest fires.

In this case, two types of chained natural disaster were combined, the heat wave and forest fires. These disasters reinforced each other by making the environment unbreathable, causing the number of deaths reported. Because of this, the heat wave is recorded as the one that has caused the most deaths in history.

The Joplin tornado of May 22, 2011 (Missouri, US)

This natural disaster consisted of a category 5 (maximum) tornado that occurred in the North American city of Joplin in Missouri. It was a multi-vortex tornado that killed 162 people and partially destroyed the city.

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