Dangerous geological phenomena and processes

The natural disasters that have taken place in various parts of the world and their consequences suggest that people have either not yet studied these processes and the reasons for their occurrence, or they do not observe the rules of safety in potentially dangerous places.

If it was different, there would not be so many human casualties. Their number suggests that dangerous geophysical and geological phenomena are still in the process of studying by scientists around the world.

The concept of a natural disaster

Any natural phenomena that lead to destruction or changes in the external environment are qualified as natural disasters.

They can be geological, geophysical, meteorological, hydrological, biological, ecological or even cosmic. 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 the region taken separately. In addition to natural, there are dangerous engineering and geological processes and phenomena, most often manifested during construction in an unsuitable place or human intervention in the natural environment.

The term "disaster" is used in the case of the great destructive consequences of a natural phenomenon. The word "spontaneous" 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 not always capable of "warning" the population of the impending danger. For example, the origin of a tsunami is difficult to foresee, even knowing about the processes occurring at the bottom of the oceans.

To identify changes and eliminate the consequences of natural disasters in all countries of the world there are special organizations.

The concept of geological disaster

Dangerous geological phenomena are not uncommon 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 passing its stages of development.

Dangerous natural phenomena of a geological nature are disasters caused by the state of the planet's lithosphere. These, above all, include geophysical processes - earthquakes and volcanic eruptions. Geological disasters are landslides and mudslides. 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 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 bowels of the Earth have their reflection on its surface in the form of earthquakes. Such dangerous geological phenomena are related to the fact that the internal tectonic processes of the Earth affect its outer layers.

Imperceptible to humans, but movement of tectonic plates captured by sensitive technology, the continents are constantly in motion. The same applies to mountains and faults in the earth's crust. All this is the cause of the occurrence 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 the two seismic zones of the planet - the Mediterranean-Asian and Pacific.

The main work of scientists-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 fixed in points.

Earthquake victims

There is evidence that in the extreme antiquity, geological hazards occurred. Examples of this are those that have gone under water or destroyed cities. According to the calculations of 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 carried out in a short time thousands of human lives:

• Indonesia 2006 - 6618 victims.
• Indonesia 2009 - more than 1500 people.
• Haiti 2010 - 150,000 victims.
• Japan 2011 - 18,000 people.
• Nepal 2015 - more than 4000 dead.

These dangerous geological phenomena occurred in the early 21st century, which indicates that the underground tectonic activity on the planet is still quite high.

Volcanoes

The hot magma in the core of the Earth is in constant motion, and when tectonic plates shift as fractures and cracks appear, it rushes to the surface of the earth's crust under great pressure. Thus, dangerous natural phenomena are manifested - geological disasters in the form of volcanic eruptions.

Scientists classify 3 types of volcanoes :

• Extinct volcanoes are known for their eruptions before civilization appeared on Earth. Only in their structure and sediments in the craters, scientists can judge how powerful they were and when they ceased to be active.
• Dangerous volcanoes belong to geological hazards, although their last eruptions could have been many centuries ago. Nevertheless, they from time to time "come to life" from the processes that occur deep in the bowels of the Earth. They are 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 are permanent processes that cause earthquakes and magma emissions.

To date, the largest number of active volcanoes falls on the Indonesian archipelago, known as the "Fire Ring". The archipelago of 40,000 km in length mainly consists of tectonic faults, which constitute almost 90% of all the volcanoes of the planet.

Volcanoes are not so terrible in themselves, as those dangerous geological phenomena that accompany them - the release of gases and ash into the atmosphere, the eruption of lava, mud flows, earthquakes and tsunamis.

Consequences of volcanic eruptions

The phenomena that accompanied the eruption of the volcano include:

• Lava flows - consist of earth rocks, melted 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 several cm / hour, and reach up to 100 km per hour.
• The volcanic cloud is one of the most dangerous phenomena, since it consists of hot gas and ash, which are all burned on their way. For example, during the eruption of the volcano Mont-Pele (Martinique) in 1902, a similar cloud, swept at a speed of 160 km / h, in just a few minutes, killed 40,000 people.

• Mud flows and lahars. Mud is formed from volcanic ash, and Lahars is a mixture of melted snow, earth and stones. Under Lahara in 1985, a whole city (25,000 people) was killed during the eruption of Nevado del Ruiz (Colombia).
• Volcanic gas, consisting of sulfur oxide and hydrogen sulfide, is deadly to humans.

This is by no means all the dangerous geological processes and phenomena that accompanied volcanic eruptions. This terrible kind of cataclysm is inherent in our age, as well as throughout the course of human history.

Landslides

If volcanoes and earthquakes are geophysical phenomena, then natural disasters like landslides, avalanches and mudflows are geological processes.

The cause of landslides (rock formation) is now 80% unreasonable activity of people. Usually rocks accumulate for a long time and can not move from their place for decades, but changing the slope of the mountain, seismic shocks, washing up with rain or streams can change everything in a matter of seconds.

The descent of landslides due to human activities is associated with cutting down trees, improper farming on mountain slopes and carrying out soil.

According to the area they occupy and what depth the layer of soil, landslides are divided into small, medium and large-scale. At the location of these dangerous natural phenomena (geological reasons for the shift of the rock) can be mountain, underwater, combined and artificial. The latter are connected with the activities of people - excavations, dumps of mines, canals.

Celt

Another dangerous for human life natural cataclysm is the descent of the mudflow. It consists of water, mud and stones and is most often associated with raising the water level in mountain rivers. Even though the gathering takes 1 to 3 hours, the harm that it can inflict is irreparable. For example, at the descent of the mudflow in Peru in 1970, several cities with a total of more than 50,000 victims were destroyed.

The reason for the occurrence of mudflow are most often rain or melting snow on the top of the mountain. According to their composition, they are divided into mud, mud and water stone. To avoid human casualties, dams are erected in mudflowable areas, which let water pass, but stop the flow of stones and mud. Building watercourses and drainage ditches is also considered effective.

There is no exact definition of the time for the descent of the mudflow, but one can approximately calculate its probability by the amount of precipitation (in case of stormy origin) or an increase in the average temperature (glacial mudslides).

Avalanche

As the scientists note, more than 80% of snow avalanches descend due to human activities. Nowadays it's tourists of ski resorts, wishing 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, the avalanche can pick up speed up to 100 km / h. Descending from the mountain, a small initially, it increases, "snatching" along the way snow and rocks. It is impossible to stop the avalanche. Usually its demise ceases with a descent to the foot of the mountain.

In the history of this geological phenomenon there are multiple human victims, according to the number of which the avalanche can be called a catastrophe. 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 definition broader than a simple natural disaster. Earth is known for cataclysms that caused global or local changes in the climate and structure of the relief.

From examples of disasters that have occurred in our time, we can name the eruption of the volcano Krakatau (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 scattered by 500 km. From the ash, which was long in the atmosphere, the temperature on the planet dropped by 1.2 degrees.

Fractures in the earth's crust, caused by earthquakes, can cause an ecological catastrophe. Change in the landscape causes 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 creates additional stress on tectonic processes. During the erection, for example, of dams, there is a disturbance of the terrestrial masses, which crumble under the influence of external loads.

This happened in the 19th century in France. The sandstone layer under the dam could not stand the mass of the structure and sagged, which led to a change in the landscape and human casualties.

Explosions of the soil produced during construction, incorrect calculations and lack of knowledge of the ongoing tectonic processes in each individual section of the earth's crust often lead to catastrophes. To avoid this, norms for engineering and geological research have been worked out.

The simplest knowledge of human life safety is studied in schools.

The study of natural phenomena in school

The school subject, studying dangerous geological phenomena, OBZH, gives the basic knowledge necessary for children to understand the natural processes taking place on the Earth.

The subject "Fundamentals of human life safety" provides for the emergence of schoolchildren knowledge and skills to behave correctly, survive and provide first aid in hazardous situations associated with natural phenomena.