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Earthquakes: What happens when plates rub the wrong way

Aftershocks, faults, magnitudes and more

A car is crushed under a home that collapsed after the previous day's magnitude 6.4 earthquake in Yauco, Puerto Rico, Wednesday, Jan. 8, 2020. More than 250,000 Puerto Ricans remained without water on Wednesday and another half a million without power, which also affected telecommunications. (AP Photo/Carlos Giusti)
A car is crushed under a home that collapsed after the previous day's magnitude 6.4 earthquake in Yauco, Puerto Rico, Wednesday, Jan. 8, 2020. More than 250,000 Puerto Ricans remained without water on Wednesday and another half a million without power, which also affected telecommunications. (AP Photo/Carlos Giusti) (Copyright 2020 The Associated Press. All rights reserved.)

ORLANDO, Fla- – Unlike the weather, earthquakes can’t be predicted. According to the United States Geological Survey, scientists can only calculate the probability that a significant earthquake will occur in a specific area within a certain number of years.

Any planet that has water, will have earthquakes as land masses slowly move toward and away from one another. An earthquake is caused by a sudden slip on a fault. When stress that has built up along a fault overcomes friction, energy is released in the form of seismic waves that travel through the earth’s crust. These waves cause the ground to shake. Earthquakes happen every day, some can’t be felt at all, but strong quakes can cause widespread destruction. Where the earthquake occurs is known as the epicenter.

Magnitudes:

Earthquakes are measured on the Richter Scale. Similar to how hurricanes are categorized with the Saffir-Simpson Scale, the higher the magnitude, the more intense the earthquake is.

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Each whole magnitude increase equals a quake 10 times stronger. For example, a 6.0 magnitude earthquake is 10 times stronger than a 5.0 magnitude quake.

What is fault?

A fault is fracture between two blocks of rock which allow the block to move relative to each other. There are several different types of faults that are classified by scientists. Large faults within the earth’s crust are a result of plate tectonics.

What is a plate?

A plate is a very large sheet of rock that forms the surface of the earth. The earth is made up of several plates that slowly glide apart or toward one another. These bodies only move several centimeters a year on average.

Not all faults are created equal. Here are a few common faults.

Strike-slip fault:

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The San Andreas fault in California may be the most well-know strike-slip fault. With this type of fault, two land masses are moving in different directions. These landmasses build up friction and then slip when that friction is overcome. Think of rubbing two pieces of sand paper together.

Oblique-slip fault:

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This type of fault is responsible for the devastating January earthquakes in Puerto Rico. This type of fault is similar to the strike-slip fault, but with this type, there is an added displacement of the land up or down.

Subduction zone fault:

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These are typically the cause of most catastrophic earthquakes. In this scenario, you have one plate slide underneath another plate creating enormous pressure. Think of pulling back a rubber band and then releasing it. Tsunamis are the most likely with this type of earthquake. This type of fault was responsible for the catastrophic 9.1 magnitude earthquake and tsunami in Japan in 2011 and in Indonesia in 2004.

Aftershocks are smaller earthquakes that occur after the main earthquake in the same general area.


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