In this article we will look at causes of earthquakes. The very concept of an earthquake is known to all people, and even children, but what are the reasons for the sudden start of the earth’s movement and the collapse of everything around it?
First of all, it must be said that earthquakes are conventionally divided into several types: tectonic, volcanic, landslide, artificial and man-made. All of them we briefly consider right now. If you want to know interesting facts about nature, be sure to read to the end.
Tectonic causes of earthquakes
Most often earthquakes occur due to the fact that the lithospheric plates are in constant motion. The upper layer of lithospheric plates are called tectonic plates. By themselves, the platforms move unevenly and constantly put pressure on each other. However, they remain alone for a long time.
Gradually, the pressure increases, with the result that the tectonic platform makes a sudden jolt. It is he who vibrates the surrounding rock, which is why an earthquake happens.
San Andreas Rift
Transform faults are huge cracks in the Earth, where the platforms “rub” against each other. Many readers should be aware that the San Andreas Fault is one of the most famous and long transform faults in the world. It is located in the state of California in the United States.Photo of the San Andreas Fault
Platforms moving along it cause devastating earthquakes in the cities of San Francisco and Los Angeles. An interesting fact: in 2015 in Hollywood they released a film with the name “San Andreas Rift”. He talks about the corresponding disaster.
Volcanic causes of earthquakes
One of the causes of earthquakes are volcanoes. Though they do not produce strong fluctuations of the earth, they last long enough. Causes of aftershocks are due to the fact that deep in the bowels of the volcano, the tension generated by lava and volcanic gases is increasing. As a rule, volcanic earthquakes last for weeks and even months.
However, the history of cases of tragic earthquakes of this type. As an example, Krakatau volcano is located in Indonesia, the eruption of which occurred in 1883.Krakatau is still sometimes excited. Real photo.
The force of its explosion at least 10 thousand times the force of the atomic bomb dropped on Hiroshima. The mountain itself was almost completely destroyed, and the island fell into three small parts. Two thirds of the land disappeared under water, and the rising tsunami destroyed all those who still had a chance to escape. More than 36,000 people died.
Landslide causes of earthquakes
Earthquakes caused by giant landslides are called landslides. They are local in nature, and their strength, as a rule, is small. But there are exceptions. For example, in Peru, in 1970, a landslide of 13 million cubic meters, descended from Mount Hascaran at a speed of over 400 km / h. Killed about 20,000 people.
Man-made causes of earthquakes
Earthquakes of this type are due to human activity. For example, artificial reservoirs in places not intended for this by nature, with their weight provoke pressure on the plates, which serves to increase the number and strength of earthquakes.
The same applies to the oil and gas industry, when large quantities of natural materials are extracted. In short, man-made earthquakes occur when a person took something from nature from one place, and shifted it without asking for another.
Artificial causes of earthquakes
By the name of this type of earthquake, it is easy to guess that the blame for it lies entirely on the person.
For example, the DPRK in 2006 experienced a nuclear bomb, which caused a small earthquake recorded in many countries. That is, any activity of the inhabitants of the earth, which is guaranteed to cause an earthquake, is an artificial cause of this type of disaster.
Can earthquakes be foreseen?
Indeed it is possible. For example, in 1975, Chinese scientists predicted an earthquake and saved many lives. But with an absolute guarantee it can not be done even in our days. The supersensitive device that registers an earthquake is called a seismograph. On the spinning drum, the oscillation of the earth is recorded by a recorder.Seismograph
Animals before earthquakes also acutely feel anxiety. Horses start to stand up for no apparent reason, dogs strangely bark, and snakes crawl out of the holes on the surface.
As a rule, earthquake strength is measured by the Earthquake Scale. We give all twelve points so that you have an idea of what it is.
- 1 point (imperceptible) - an earthquake is recorded exclusively by instruments;
- 2 points (very weak) - can be seen only by domestic animals;
- 3 points (weak) - perceptible only in some buildings. Feels like driving in a car over bumps;
- 4 points (moderate) - seen by many people, can cause the movement of windows and doors;
- 5 points (quite strong) - glass jingles, hanging objects swing, old whitewash can crumble;
- 6 points (strong) - during this earthquake, light damage to buildings and cracks in substandard buildings are noted;
- 7 points (very strong) - at this stage the buildings suffer significant damage;
- 8 points (destructive) - destruction in buildings is observed, chimneys and cornices fall, on the slopes of the mountains one can see cracks of a few centimeters;
- 9 points (devastating) - earthquakes cause collapses of some buildings, old walls collapse, and the rate of crack propagation reaches 2 centimeters per second;
- 10 points (destroying) - in many buildings collapses, in the majority - serious destruction. The soil is streaked with cracks up to 1 meter wide, there are landslides and landslides;
- 11 points (disaster) - large landslides in the highlands, numerous cracks and a picture of the general destruction of most buildings;
- 12 points (severe disaster) - the relief is globally modified almost before our eyes. Huge collapses and total destruction of all buildings.
In principle, on a twelve-point scale of earthquakes, you can evaluate any disaster caused by the earth’s tremors.
In the end, it should be added that it is rather difficult to establish the true causes of the earthquake. This is due to the fact that natural mechanisms are so complex that they have not been fully studied until now.