Mankind knows little about the structure of the earth. Moreover, it is impossible to control many of its internal processes. Earthquakes, which cover a certain part of the earth’s surface and turn it into ruins in a matter of seconds, also belong to such phenomena.
California Largest Earthquake
One of the largest earthquakes occurred in California (USA). This has not happened for about 25 years. The territory was subject to fluctuations of 6 points. It happened on 08.24.2014 at 03.20 a.m. local time. It was at this time that the residents of San Francisco felt the first tremors.
Despite significant damage to buildings and communications, human casualties were avoided. Although about 80 people were still affected.
What allowed to avoid numerous victims?
Many believe that the number of victims is relatively small due to the special security system that was created as an experiment in California. Its essence is to warn the population about a possible cataclysm. The California earthquake (2014) showed that the system is working. She announced the upcoming jolt in 10 seconds.
The well-known edition of The Los Angeles Times wrote about this, that "in these seconds, you can only not get out of bed." In many ways they are right, but work is underway to provide such a system to all residents of the state and refine it so that the warning signal arrives 50 seconds before the cataclysm.
The system works with the help of seismographs that record shocks at the epicenter. They are the first to be able to feel the push and send a signal to people at such a speed with which it will reach before the earthquake. Thus, people will be able to prepare for the elements.
The earthquake in California once again showed the fragility of human structures. Although optimism adds a triggered alert system. Of course, 10 seconds is not enough to evacuate, but progress does not stand still. In the future, even 50 seconds can save more than one life.
The California earthquake was not the only one in the history of this region and the United States as a whole. In recent years, this state has ceased to be a leader in the number of shocks.
Oklahoma - the new leader in the number of disasters in the United States
Most residents of this state until 2008 had no idea what an earthquake in the United States. They were far from these problems. However, in recent years, 240 shocks of magnitude up to 4 points have been recorded in this territory.
Most experts agree that this is due to shale gas production. The same opinion is shared by the professor at Columbia University, Jeffrey Abers. He claims that approximately 2, 000 km² of Oklahoma territory is at risk. In a few years, the state has evolved from the most seismic hazardous location in the United States.
The main reason is called shale gas production by the method of hydraulic fracturing. It consists in the fact that a small amount of water with chemicals is injected under high pressure into shale formations. Thus, fossil fuels are freed. As scientists at Cornell University have proved, it is precisely such actions that can cause an earthquake in the United States and other countries within a radius of 40 km from the place of mining.
Municipalities in many cities in America prohibit oil and gas companies from producing this method. In this country, in addition to man-made disasters, and so there is something to fear and something to remember.
When was America shaking the longest?
The 2014 California earthquake was not the largest in the history of the region. Much earlier, in December 1811, the movement of land began, which ceased only in March 1812. As a result of the tremors, many changes in the relief took place.
The effects of earthquakes:
- individual plots of land rose 6 m in height;
- the course of the Mississippi River has changed;
- new lakes appeared, such as St. Francis;
- a large number of people died.
Scientists suggest that 3 to 5 tremors were magnitudes greater than 8 points. The exact number of victims will never be known, since no strict documentation was maintained in the settlements.
Greatest Cataclysm in San Francisco
The 1906 earthquake in America was much shorter. It happened on April 18 and lasted only 75 seconds, but brought many human casualties and destruction.
The consequences of the earthquake:
- More than 700 people are considered dead.
- Both new buildings, for example, the municipality, and dilapidated houses were destroyed.
- Sonoma wine company was busted due to the complete destruction of its wine storage.
- As a result of the outbreak of fire, about 12 km² were burned. Many insurance companies paid damages to the victims and went bankrupt as a result.
- The city water reservoir and gas storage were completely destroyed.
The shock power is estimated at 8.3 points. This crippled the city for $ 500 million. Hundreds of human lives were claimed by this earthquake.
The strongest earthquake in history
It is unlikely that an earthquake in California could compare with what happened in August 1950 in India. It happened in the east of the country, in the state of Assam. The tremors were so strong that the special equipment could not fix them. Sensors were not designed for such indicators.
When everything stopped, the experts officially assigned the tremors a magnitude of 9 points. The cataclysm brought huge losses, destruction. There were human casualties. It lasted five days. As a result of prolonged shocks, more and more faults formed, people instantly lost not only their homes, but also their own lives. Thick hot steam escaped from the resulting cracks.
The damage from the largest earthquake in the world amounted to $ 25 million. In addition to human casualties, the worst was the complete destruction of infrastructure. Dams, dams, roads were destroyed. All this led to many other problems, including complicating the search and rescue of survivors.
Many residents had no choice but to escape in the trees. Newspapers have described many such cases. One of them especially stood out when a woman had to give birth to a child on a tree.
Where did it really shake?
The waves of these shocks on August 15 reached America. US equipment recorded them at home. Researchers have suggested that they come from the Japanese islands. There, in turn, they also recorded similar indicators and decided that the cataclysm covered the United States.
At first, none of them even thought that these waves were echoes of the earthquake in India. His power spread to a significant part of the Earth.
India has long had an unstable position of the earth's crust. That is why earthquakes and floods occur here. In the second half of the 19th century, similar disasters with a magnitude higher than 8 points already occurred in India.
Why are earthquakes?
In order to calculate in advance the places where tremors will occur, and to avoid many victims, it is necessary to understand why they occur. Scientists do not fully know how and why many disasters arise. There are several versions regarding earth tremors.
The main causes of earthquakes:
- Ceiling failures in voids formed underground. These shocks have a small area of coverage, but cause a lot of serious damage. Similar causes include human activities, namely the pumping of oil and gas from underground.
- Volcanic eruptions are most often accompanied by serious earthquakes. This is associated with the sudden discharge of gases that accumulate in the channel of the volcano. After the eruption of lava, the above-mentioned voids can also form.
- Tectonic earthquakes in the world are considered the most destructive. They are associated with the movement of platforms and faults in the granite layers of the earth's crust. An example is the incident in California. All of them are associated with the San Anderas Fault. It is along it that seismic waves regularly form, which, depending on speed, bring less or more significant damage to this state.
Is it possible to predict a cataclysm?
The ability to make a correct forecast of earthquakes is the main task of seismologists. Thousands of stations operating across the planet follow the internal movement of the Earth, which never stops.
For forecasting, knowledge is often used that an earthquake is an avalanche-like propagation of a crack in the earth's crust. They happen at fault sites. That is why observations and measurements are carried out in seismically hazardous areas. The cessation of the internal processes of the Earth is a high probability that an earthquake will soon occur.
Scientists create special maps that display information about the centers of tremors, their intensity, frequency. Prediction is carried out in three stages.
Stages of creating a forecast:
- Identification of seismically dangerous zones for 10-15 years.
- Medium-term forecast for 1-5 years.
- Short-term forecasting with a high probability of a cataclysm in a given area.
