What causes earthquake indeed? Well, Earth is basically a giant lump that consists of rock. It may even similar to freshly boiled egg with hot and molten core that bubbles away inside the thin outer crust of the earth. Actually, we live on the top of tectonic plates, the enormous rocky slabs that can slide. Yes, we live on an eggshell. So, it is very possible that one minute you walk down the street just happily and safely. But the next minute, the street walks all by itself indicating an earthquake is happening. When it happens, all the buildings start to shake with glass and bricks rain down around you. You notice there are huge crates that appear on pavements with so many people screaming in fear. It even feels like the world has finally come to an end.
Those are fearful descriptions of an ongoing earthquake. Unfortunately, we as human cannot do much to prevent or stop it from happening. Instead, we can only predict where the next earthquake will happen. But, we cannot even predict the accurate locations. So, we can only prepare for the next earthquake while hoping there will be not many lives at stake.
In short answer, the cause of earthquake is faulting vertical or sudden lateral movement of rack beneath the surface. The earthquake happens at the faults. This is a particular place where the two tectonic plates jagged edges grind against one another. According to the report, most of the earthquakes happen in the ocean. Oceans are the exact places where the tectonic plates push apart on the sea’s floor. In fact, some of the worst earthquakes had happened in Pacific Ocean. This is the reason why there is the so called area Ring of Fire in the Pacific Ocean.
Actually, the earth’s tectonic plates move very slow that we do not even realize. And when the two grinding plates jolt suddenly into new position, it will release an energy which finally creates earthquake. Epicenter is the location of the worst and greatest damages. Once an earthquake happens, it will only stop after all the energy at the Earth’s focus has been dissipated. However, there is still even chance for aftershocks, the further earthquakes.
Apparently, there are also possibilities of human-induced earthquakes. This kind of earthquake has been documented in several parts of the world such as Canada, Japan and United States. Usually, it is caused by injection of fluid into the so called deep wells that are used for secondary oil recovery or waste disposal. But, there are considerably minor earthquakes. In 1967, there was the largest human-induced earthquake happened in Rocky Mountain, Arsenal, Colorado. It was 5.5 Mag earthquake that was followed by a series of aftershocks or smaller earthquakes. Following this earthquake, the injection was finally discontinued.
There is also important fact regarding seismic waves caused by underground explosions that are similar to earthquake. Usually, the explosions are set off in order to break the rock to make railroads, tunnels, mines or subway. Some of these waves may occur during the collapse of mine’s walks. Even the largest underground explosions following nuclear warheads can also create seismic waves that are very similar to earthquake.
The earthquake is classified into three different groups according to the focus’ depth.
In every earthquake, one of the main jobs of the scientists of professionals is to measure the earthquake. It is significantly critical to distinguish major earthquakes that cause major damage to minor earthquake that cause almost no fatalities. Usually, measuring it is done by using number of Richter scale and Mercalli scale.
The Richter Scale is known as the scientific measurement of the earthquake’s strength. It was developed in 1935 by Charles F. Richter. Usually, earthquake with less than 2.0 Mag on Richter scale is considered micro earthquake. The major earthquake causing damage is usually 8.0 Mag on Richter scale and above. The earthquake that happened in Aceh Indonesia and several countries in Asia in 2004 was among the worst earthquake that was followed with tsunami. Japan afterward also experienced major earthquake and tsunami.
With this information, it is definitely clear how every earthquake actually happens. Although we as human have no power to prevent but lowering the fatalities is still a necessary effort to do.