Geology And Geophysics

How Earthquakes are Caused

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Many places on the planet experience earthquakes, either on a regular basis or infrequently. Earthquakes occur in specific areas of the Earth’s crust where “faults,” or cracks lie. These faults experience changing temperatures and pressures within the layers of the Earth that cause them to shift dramatically.

The Earth’s Layers

The Earth has 4 major layers, the inner core, the outer core, the mantle and the crust. The thin skin of the planet is made up of the crust and top of the mantle. The skin of the planet is not one continuous piece of skin. Instead, it is pieces that fit together much like a jigsaw puzzle. These pieces are called “tectonic plates,” and they constantly move and shift around. The spaces in between the pieces are known as “faults.” Earthquakes occur at these fault lines between the pieces. As they move, the plates get stuck together at these fault lines, and when they break free, an earthquake occurs.

Pressure and Friction

As the force from the plates builds up, it creates pressure and friction on the tectonic plates, causing a buildup of energy. When the edges of the plates become unstuck, it releases this energy in the form of an earthquake, with shaking in many directions like ripples on a pond. Anything resting on the surface of the ground when this occurs can be damaged and broken apart from the force.

Damage From Earthquakes

The release of pressure from within the Earth’s crust can cause enormous damage. Trees can become uprooted, landslides can occur and avalanches can bury thousands of people in populated areas. Skyscrapers, power plants and factories could collapse, taking many lives. Aftershocks, tsunamis and floods that occur after earthquakes are other dangers associated with earthquakes.  Even after a quake, fire, gas leaks and explosions could kill many more. Those people living in earthquake-prone areas should learn as much as possible about safety measures during a quake in order to protect their own lives and the lives of their families.

Measuring Earthquakes

Earthquakes are recorded and measured on instruments called seismographs. A seismograph sits on the ground with a heavy weight that hangs free. When the earth shakes the device records the difference between the part of the instrument that moves and the part that does not move. This difference in these positions is the “magnitude” of the earthquake event.

Earthquakes are natural phenomena that mankind has learned to endure. There is no device that can predict earthquakes. We must rely upon improved building codes to help minimize the damage from these events.

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