The natural disasters that have taken place in different regions of the planet and their consequences indicate that people either have not yet sufficiently studied these processes and the causes of their occurrence, or they do not follow the safety rules for living in potentially dangerous places.
If it were different, there would not be so many casualties. Their number suggests that dangerous geophysical and geological phenomena are still in the process of being studied by scientists around the world.
Natural disaster concept
Any natural phenomena that entail destruction or changes in the external environment are qualified as natural disasters.
They can be geological, geophysical, meteorological, hydrological, biological, environmental or even space in nature. That is, they are caused by one of the factors that change the structure, shape, or climatic features of both the planet as a whole and an individual region. In addition to natural, there are dangerous engineering and geological processes and phenomena that most often occur during construction in an unsuitable place for this or human intervention in the natural environment.
The concept of "disaster" is applied in case of large destructive consequences of any natural phenomenon. The word "spontaneous" in this case means the unforeseen nature of the cataclysm. Long-term studies of the Earth’s structure, its climate and location in space, as well as the most accurate and sensitive equipment, are far from always able to “warn” the population of imminent danger. For example, the occurrence of a tsunami is difficult to predict, even knowing the processes occurring at the bottom of the oceans.
Special organizations exist to identify changes and eliminate the consequences of natural disasters in all countries of the world.
The concept of geological disaster
Dangerous geological phenomena are far from rare these days. Although according to rough estimates of scientists, the Earth is more than 4.5 billion years old, relative to other objects in space, it is still a young planet undergoing its stages of development.
Dangerous natural phenomena of a geological nature are disasters caused by the state of the planet's lithosphere. These primarily include geophysical processes - earthquakes and volcanic eruptions. Geological disasters are landslides and mudflows. All of them have their own power levels, qualified by scientists on a special scale.
In addition to studying such phenomena, there are a number of standards and rules that provide for the urgent evacuation of the population and the elimination of natural disasters.
Earthquakes
All processes occurring in the bowels of the Earth are reflected on its surface in the form of earthquakes. Such dangerous geological phenomena are associated with the fact that the internal tectonic processes of the Earth affect its outer layers.
The movement of tectonic plates, invisible to people, but captured by sensitive technology, leads to the fact that the continents are constantly in motion. The same applies to mountains and faults in the earth's crust. All this is the cause of tremors. Some layers of the lithosphere descend to the mantle of the Earth, others, on the contrary, rise, and this continuous activity is characteristic of two seismic zones of the planet - the Mediterranean-Asian and Pacific.
The main work of seismologists is to study the forces that affect the earth's crust, their frequency and strength. To determine the intensity of earthquakes, there is a special table in which the depth and power of the shocks are recorded in points.
Earthquake victims
There is evidence that geological hazards occurred in ancient times. Examples of this are those that have gone under water or destroyed cities. According to scientists, the intensity and frequency of earthquakes 10-12 thousand years ago were much higher. This means that processes in the bowels of the earth are gradually slowing down.
Nevertheless, in our time there are numerous examples of earthquakes that claimed thousands of human lives in a short time:
- Indonesia 2006 - 6,618 casualties.
- Indonesia 2009 - more than 1,500 people.
- Haiti 2010 - 150,000 victims.
- Japan 2011 - 18,000 people.
- Nepal 2015 - more than 4,000 dead.
These dangerous geological phenomena occurred at the beginning of the 21st century, which suggests that the underground tectonic activity on the planet is still quite high.
Volcanoes
The red-hot magma in the Earth's core is in constant motion, and when faults and cracks appear as a result of the shift of tectonic plates, it rushes to the surface of the earth's crust under high pressure. Thus, dangerous natural phenomena are manifested - geological natural disasters in the form of volcanic eruptions.
Scientists classify 3 types of volcanoes :
- Extinct volcanoes are known for their eruptions before civilization appeared and developed on Earth. Only by their structure and deposits in the craters can scientists judge how powerful they were and when they ceased to be active.
- Geological hazards include dormant volcanoes, although their last eruptions could have been centuries ago. Nevertheless, from time to time they come to life from processes that occur deep in the bowels of the Earth. They pose a potential threat to people, as they can "wake up" at any time.
- The greatest danger to human life is represented by active volcanoes, in whose bowels there are constant processes that cause earthquakes and magma emissions.
To date, the largest number of active volcanoes are in the Indonesian archipelago, known as the Ring of Fire. The archipelago with a length of 40,000 km consists mainly of tectonic faults, which make up almost 90% of all volcanoes on the planet.
Volcanoes themselves are not so terrible as the dangerous geological phenomena that accompany them - the emission of gases and ash into the atmosphere, the eruption of lava, the flows of mud, earthquakes and tsunamis.
The consequences of volcanic eruptions
The phenomena that accompanied the volcanic eruption include:
- Lava flows - consist of terrestrial rocks, molten to a temperature of 1000 or more degrees. The movement of the lava depends on its density and the slope of the mountain and can be as small as several cm / hour, or reach 100 km per hour.
- A volcanic cloud is one of the most dangerous phenomena, as it consists of hot gas and ash, which all burn in their path. For example, during the eruption of the volcano Mont Pele (Martinique) in 1902, such a cloud, which swept at a speed of 160 km / h, killed 40,000 people in just a few minutes.
- Mud flows and lahars. Mud is formed from volcanic ash, and lahars are a mixture of melted snow, earth and stones. Under Lahara, in 1985, a whole city (25,000 people) died during the eruption of Nevado del Ruiz (Colombia).
- Volcanic gas, consisting of sulfur oxide and hydrogen sulfide, is deadly to humans.
These are far from all dangerous geological processes and phenomena that accompanied volcanic eruptions. This terrible kind of cataclysm is inherent in our century, as well as throughout the entire course of human history.
Landslides
If volcanoes and earthquakes are geophysical phenomena, then natural disasters such as landslides, avalanches and mudflows are geological processes.
The cause of landslides (gathering of rocks) today is 80% unreasonable activity of people. Typically, rocks accumulate for a long time and may not budge for decades, but a change in the slope of the mountain, seismic shocks, washed by rains or streams can change everything in a matter of seconds.
The loss of landslides due to human activities is associated with felling of trees, improper farming on mountain slopes and removal of soil.
According to the area they occupy and the depth of the soil layer, landslides are divided into small, medium and large-scale ones. At the location of these dangerous natural phenomena (geological causes of rock shift) can be mountain, underwater, combined and artificial. The latter are associated with the activities of people - pits, dumps of mines, channels.
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Another natural cataclysm dangerous to human life is the debris flow. It consists of water, mud and stones and is most often associated with rising water levels in mountain rivers. Even though the gathering of mudflows takes from 1 to 3 hours, the harm that it can cause is irreparable. For example, during the mudflow in Peru in 1970, several cities were destroyed with a total number of victims of more than 50,000 people.
The cause of mudflows is most often rains or snowmelt at the top of the mountain. In their composition, they are divided into mud, mudstone and water. To avoid human casualties, dams are built in mudflow hazardous areas that allow water to pass through but stop the flow of stones and dirt. Also considered effective is the construction of watercourses and catchment ditches.
There is no exact determination of the time of mudflow discharge, but its probability can be approximately calculated by the amount of precipitation (if it is stormy) or the average temperature increase (glacial mudflows).
Avalanche
According to scientists, more than 80% of avalanches go off due to human activities. Nowadays, these are tourists of ski resorts who want to get a "portion" of adrenaline. An avalanche is a mass of snow formed as it accumulates on mountain slopes.
As they accumulate, these snow layers become heavier until they break down from the slightest push or thaw. Depending on the steepness and height of the slope, an avalanche can gain speed up to 100 km / h. Going down the mountain, small initially, it increases, "grabbing" snow and stones along the way. It’s impossible to stop the avalanche. Usually its descent stops with the descent to the foot of the mountain.
In the history of this geological phenomenon there are numerous human victims, according to the number of which an avalanche can be called a disaster. For example, in Turkey, from 1191 to 1992, more than 300 people became victims of this phenomenon.
Changes on the planet
As can be seen from the above natural processes, a dangerous geological phenomenon is a broader definition than just a natural disaster. Earth is aware of the cataclysms that caused global or local changes in climate and terrain.
Examples of disasters that have occurred in our time include the eruption of the volcano Krakatau (1883), which caused climate change for 5 years. A column of gas and ash during the explosion of a volcano rose almost 70 km in height, and its fragments scattered over 500 km. From the ashes that have been in the atmosphere for a long time, the temperature on the planet has dropped by 1.2 degrees.
Faults in the earth's crust caused by earthquakes can cause environmental disasters. Changing the landscape causes the destruction of the habitat for the plants growing there and the living fauna.
Engineering-geological phenomena
The reason for the manifestation of many dangerous geological phenomena is man. Engineering and construction activities of people create additional loads on tectonic processes. During the erection of, for example, dams, there is a violation of the earth's masses, which collapse under the influence of external loads.
This happened in the 19th century in France. The sandstone layer under the dam could not withstand the mass of the structure and sank, which led to a change in the landscape and human casualties.
Explosions of the soil produced during construction, incorrect calculations and a lack of knowledge on the tectonic processes in each individual section of the earth's crust often lead to disasters. To avoid this, standards for engineering and geological surveys have been developed.
The simplest knowledge on human life safety is studied in schools.
Studying natural phenomena at school
A school subject that studies dangerous geological phenomena, life safety, provides basic knowledge necessary for children to understand the natural processes occurring on Earth.
The subject “Fundamentals of life safety” of a person provides for the appearance in schoolchildren of knowledge and skills to behave properly, survive and provide first aid in dangerous situations associated with natural phenomena.