An earthquake (also called a temblor, tremor or quake) is the detectable shaking of the Earth’s surface, resulting from the impulsive release of energy in the crust of Earth which develops seismic waves. Earthquakes can be very violent to toss individuals around and damage entire cities. The seismic or seismicity activity of an area refers to the size, type and frequency of earthquakes experienced over some period.
Tectonic earthquakes happen any place in the earth where there’s enough stored elastic strain energy to initiate fracture propagation along the fault plane. The sides of the fault occasionally move past each other seismically and smoothly only if there are no asperities or irregularities along the fault surface which raise the frictional resistance. Many fault surfaces have such asperities, and this results in the formation of stick-slip behavior. Once a fault has locked, constant relative motion between the plates causes an increase in stress and therefore, stored strain-energy in the capacity around the fault surface.
This lasts till the stress has increased sufficiently to break through the asperity, abruptly letting sliding over the locked part of the fault, discharging the stored energy. This energy is discharged as a combination of frictional heating of the fault surface, radiated elastic-strain seismic waves, and the cracking of the rock, hence causing an earthquake. This process of a steady build-up of stress and strain punctuated by irregular sudden earthquake failure is known as the elastic-rebound theory.
It’s estimated that only 10% or less of the total energy of an earthquake is radiated as seismic energy. A significant amount of earthquake’s energy is used to power the growth of earthquake fracture or is transformed into heat produced by friction. Therefore, earthquakes reduce the available elastic potential energy of the Earth and increase its temperature, although these variations are insignificant compared to the convective and conductive flow of heat out from the deep interior of the Earth.
Therefore, if your mind is very curious, let’s look at ten interesting facts about earthquakes.
1. Interestingly, when an earthquake happens, the shaking ground itself isn’t accountable for killing people. Landslides, the collapse of buildings, volcanic eruptions, avalanches, and tsunamis initiated by earthquakes are really responsible for killing people.
2. Earth’s 80 percent of earthquakes happen near Pacific Ring of Fire. It’s an area in the Pacific Ocean that looks like a horse-shoe. It’s the region where most of the tectonic plates of the earth meet.
3. An earthquake can release energy that’s 100 times stronger than the energy generated by the atomic bomb that was dropped on Hiroshima of Japan in 1945.
4. The biggest earthquake ever recorded on Earth was a magnitude 9.5 in Chile back in 1960.
5. The 2011 earthquake close to Japan amplified the rotation speed of Earth, reduced the day by 1.8 microseconds.
6. There are nearly 500,000 detectable earthquakes in Earth every year. 100 of them cause massive destruction and 100, 000 of those can be felt.
7. After an earthquake of 8.0 magnitude hit Mexico City in 1985, almost all newborn babies managed to survive a collapsed hospital for seven days without nourishment, warmth, water, or even human contact.
8. An earthquake on December 16, 1811, caused sections of the Mississippi River to flow backwards.
9. An earthquake can last anywhere between a few seconds and a few minutes. The lengthiest earthquake ever recorded occurred in 2004 in the Indian Ocean. It lasted for nearly ten minutes.
10. The deadliest recorded earthquake in the entire world took place in 1556 in China, killing about 830,000 people.