Natural disasters and their consequences, which have become more frequent in different regions of the planet, indicate that people either have not yet sufficiently studied these processes and their causes, or they do not follow the safety rules for living in potentially dangerous places.
If it were different, there would not have been so many human casu alties. 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 cause destruction or changes in the external environment are classified as natural disasters.
They can be geological, geophysical, meteorological, hydrological, biological, ecological or even cosmic in nature. That is, they are caused by one of the factors that changethe structure, shape or climatic features of both the planet as a whole and a single region. In addition to natural, there are dangerous engineering and geological processes and phenomena, most often manifested during construction in an unsuitable place for this or human intervention in the natural environment.
The concept of "disaster" is used in the case of large destructive consequences of any natural phenomenon. The word "natural" in this case means the unforeseen nature of the cataclysm. Long-term studies of the structure of the Earth, its climate and location in space, as well as the most accurate and sensitive equipment, are far from always able to “warn” the population about impending danger. For example, the occurrence of a tsunami is difficult to predict, even knowing about the processes occurring at the bottom of the oceans.
There are special organizations in all countries of the world to detect changes and eliminate the consequences of natural disasters.
Geological disaster concept
Dangerous geological phenomena are far from uncommon these days. Although according to rough estimates of scientists, the Earth is more than 4.5 billion years old, compared to other objects in space, it is still a young planet, going through 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.
Exceptstudying such phenomena, there are a number of regulations and rules that provide for the urgent evacuation of the population and the elimination of the consequences of natural disasters.
Earthquakes
All processes occurring in the depths of the Earth are reflected on its surface in the form of earthquakes. Such dangerous geological phenomena are connected with the fact that the internal tectonic processes of the Earth affect its outer layers.
Invisible to people, but captured by sensitive technology, the movement of tectonic plates 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 Earth's mantle, others, on the contrary, rise, and this continuous activity is characteristic of two seismic belts of the planet - the Mediterranean-Asian and the Pacific.
The main work of seismologists is to study the forces that act on 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 shocks are recorded in points.
Earthquake victims
There is evidence that geological hazards occurred in ancient times. Examples of this are submerged or destroyed cities. According to scientists, the intensity and frequency of earthquakes 10-12 thousand years ago were much higher. This means that the processes in the bowels of the Earth are gradually slowing down.
Nevertheless and inNowadays, numerous examples of earthquakes are known that claimed thousands of human lives in a short time:
- Indonesia 2006 - 6618 victims.
- Indonesia 2009 - more than 1500 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 indicates that underground tectonic activity on the planet is still quite high.
Volcanoes
Hot magma in the core of the Earth is in constant motion, and when faults and cracks appear as a result of the shift of tectonic plates, it rushes under great pressure to the surface of the earth's crust. Thus, dangerous natural phenomena appear - 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 craters can scientists judge how powerful they were and when they ceased to be active.
- Geological hazards include dormant volcanoes, although their last eruptions may have been many centuries ago. Nevertheless, from time to time they "come to life" from the processes that occur deep in the bowels of the Earth. They pose a potential threat to people, as they can "wake up" at any moment.
- The greatest danger to human life is posed by active volcanoes, in whose depths there are permanentprocesses that cause earthquakes and magma emissions.
Today, the largest number of active volcanoes are in the Indonesian archipelago, known as the Ring of Fire. The 40,000 km long archipelago is mainly composed of tectonic faults, which make up almost 90% of all volcanoes on the planet.
Volcanoes themselves are not as scary as the dangerous geological phenomena that accompany them - the release of gases and ash into the atmosphere, lava eruptions, mud flows, earthquakes and tsunamis.
Effects of volcanic eruptions
The phenomena that accompanied the volcanic eruption include:
- Lava flows - consist of terrestrial rocks melted to a temperature of 1000 degrees or more. The movement of lava depends on its density and the slope of the mountain and can range from a few cm/hour to up to 100 km/hour.
- Volcanic cloud is one of the most dangerous phenomena, as it consists of hot gas and ash, which burn everything in its path. For example, during the eruption of the Mont Pele volcano (Martinique) in 1902, a similar cloud that 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 the lahar in 1985, an entire 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.
This is not all dangerous geological processes and phenomena that accompanied volcanic eruptions. This terrible kind of cataclysm is inherent in our age, as well as throughout 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 (rock slides) today is 80% of the unreasonable activities of people. Usually, rocks accumulate for a long time and may not budge for decades, but a change in the slope of a mountain, seismic tremors, washing away by rain or streams can change everything in a matter of seconds.
Landslides due to human activities are associated with cutting down 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. By location, these hazardous natural phenomena (geological causes of rock shift) can be mountainous, underwater, combined and artificial. The latter are associated with human activities - pits, mine dumps, canals.
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Another natural disaster dangerous to human life is the mudflow. It is made up of water, mud, and rocks and is most commonly associated with rising levels.water in mountain rivers. Even though the mudflow takes 1 to 3 hours to clear, the damage it can cause is irreparable. For example, a mudflow in Peru in 1970 destroyed several cities with a total death toll of more than 50,000 people.
Mudflows are most often caused by rain or snowmelt on top of a mountain. According to their composition, they are divided into mud, mud-stone and water-stone. To avoid human casu alties, dams are erected in mudflow-prone areas that allow water to pass through, but stop the flow of stones and dirt. The construction of streams and drainage ditches is also considered effective.
There is no exact definition of the time of the mudflow, but its probability can be approximately calculated by the amount of precipitation (when it is of storm origin) or an increase in the average temperature (glacial mudflows).
Avalanche
According to scientists, more than 80% of avalanches come down 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 melt. Depending on the steepness and height of the slope, an avalanche can pick up speed up to 100 km/h. Going down the mountain, initially small, it increases, “grabbing” snow along the way andstones. It is impossible to stop an avalanche. Usually her descent stops with the descent to the foot of the mountain.
In the history of this geological phenomenon, there are multiple human casu alties, 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 natural processes listed above, a dangerous geological phenomenon is a broader definition than just a natural disaster. Earth is aware of cataclysms that caused global or local changes in climate and terrain structure.
From examples of catastrophes that have occurred in our time, we can name the eruption of Krakatau volcano (1883), which caused climate change for 5 years. A column of gas and ash during the explosion of the volcano rose almost 70 km in height, and its fragments were scattered over 500 km. From the ash, which was in the atmosphere for a long time, the temperature on the planet dropped by 1.2 degrees.
Faults in the earth's crust caused by earthquakes can cause an ecological disaster. Landscape change causes the destruction of the habitat for the plants growing there and the fauna living there.
Engineering and geological phenomena
Man is the cause of many dangerous geological phenomena. The engineering and construction activities of people create additional loads on tectonic processes. During the erection of, for example, dams, the earth masses are disturbed, which collapse under the influence of external loads on them.
This happened in 19th century France. The layer of sandstone under the dam could not withstand the mass of the structure and subsided, which led to a change in the landscape and human casu alties.
Soil explosions produced during construction, incorrect calculations and lack of knowledge on the ongoing 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 of human life safety is studied in schools.
Studying natural phenomena in school
The Geological Hazards School Subject, OBZH, provides the basic knowledge children need to understand the natural processes taking place on Earth.
The subject "Fundamentals of Human Safety" provides students with the knowledge and skills to behave correctly, survive and provide first aid in dangerous situations associated with natural phenomena.
