Earthquakes are natural disasters that happen on our planet. An earthquake happens when the earth’s plates shift and slide, sometimes resulting with catastrophic results. Scientists say that an earthquake happens almost more than every ten seconds! Earthquakes happen all the time and we usually cannot feel them, there is probably one happening right now. Not all earthquakes are devastating, but as we have seen from the news, they can be life threating. When the Earth's plates shift and move, an earthquake may happen. Earthquakes can cause aftershocks. An aftershock can mean another earthquake. An earthquake can cause a tsunami. This can happen if an earthquake starts under water. Tsunamis are huge waves from the ocean that crash down onto land. Earthquakes can cause blackouts, fires, and cause buildings to collapse. Earthquakes can happen almost anywhere in the world, but Earthquakes usually happen on faults. A fault is a crack on the earth, where land usually shifts a lot. A fault usually means that spot of earth is weak. This is where earthquakes come in. If a rock slides on a fault stress is created and if the rock breaks, shaking of the Earth starts. This is generally how an earthquake happens.
The effects of earthquakes are very devastating, and can do millions of dollars in damage. The most obvious effect of an earthquake is "ground shattering". This is the release of energy from two plates that have collided or subducted. Another destructive effect is called "faulting", when faults (large crevices in the earth) start shifting. One particular effect of an earthquake is when waterlogged earth near the surface gives way due to all the vibrations. This is known as liquefication. Another well known effect from an earthquake is an aftershock. Aftershocks are smaller, weaker earthquakes compared to the main quake. The worst effect of an earthquake is a tsunami. When an earthquake occurs, the area forced upward will push the water over the area away. Tsunamis are not to be mistaken for tidal waves, as tidal waves are affected by the gravity of the moon. Tsunamis are usually more destructive than the earthquake that generated them, due to the fact that an earthquake is local to its area, while tsunamis can spread to distant areas.
Technology with Earthquakes
Earthquakes have happened since the beginning of time, so it's no wonder that we have made technology to learn more about them.
A Seism scope was invented in the Han Dynasty in China. It was a large statue that had six-eight dragons holding golden balls, if they dropped one into a toad's mouth than an earthquake was coming that way. A seismograph is what we use today. It is a machine that measures the movements of the Earth. A geophysicist or seismologists is a scientist that studies things like earthquakes. Seismologists use seismographs to measure and compare different earthquakes. Earthquakes are sometimes measured through magnitude, to figure out magnitude we use the Richter scale. In 1935, American seismologists named Charles Richter invented the Richter scale. The Richter scale uses the surface waves and measures the height of them. An earthquake is measured to show a number like 6.3, the higher the Richter number the stronger the earthquake is. Today however, seismologists use a different scale. They use a scale called the moment magnitude scale. It is based on the Richter scale, but is supposed to be more specific than the Richter scale. There are many more scales to measure earthquakes that exist, but there are too many to go into detail.
Not only are there devices to measure the power of an earthquake, there is also technology to reduce the damage done by earthquakes. One technology is called Base Isolation.
A base isolator is put within a base of a building and, in a way, separates the building from the ground. When an earthquake occurs, the base isolators will keep the building from shaking. Base isolators can also be used for tables as well as some museums use base isolators to prevent fragile artifacts from falling onto the ground and shattering.
Where do Earthquakes Happen?
Earthquakes can just about happen anywhere in the world, but they most commonly happen on the edges of the Earth's plates... First I will explain how earthquakes on plates happen earth. The earth has a couple plates; they are separated as continental and oceanic plates. The oceanic plates are obviously in the ocean, and continental plates are everywhere else. A very deep crust of the Earth called the mantle moves these plates around. The plates are always moving and hitting each other.
Earthquakes usually happen when two plates slide against each other. Earthquakes can also happen on faults. Faults are cracks of the Earth on the edges of the Earth's plates. All the plates moving and bumping make these faults. Earthquakes happen when these faults slide in opposite directions. There are three different types of faults. They are normal, reverse and strike-slip. Normal faults are rocks that are moving up or down from each other.
Reverse faults are caused by two rocks pushing against each other. Strike-slip faults are two rocks that are moving past each other, they are not going up or down, they are moving left and right from each other. The San andreas fault in California is a strike-slip fault.