How Earthquakes Happen

Monday, December 4, 2017

An earthquake, the result of a sudden release of energy in the Earth’s crust, is measured with a seismometer. An earthquake with magnitude 3 or lower is mostly imperceptible while magnitude 7 can cause serious damage over large areas. The shaking in earthquakes can also trigger landslides and sometimes volcanic activity. In contrast, earthquakes are caused by volcanic activity, landslides, and nuclear tests.


Seismic waves which carry with them an enormous amount of energy travel through the Earth’s crust. The earthquake which seismic waves cause will vary in strength and duration. This depends on the strength of the seismic waves. Let’s discover how earthquakes happen.


The earth is divided into an inner core, outer core, mantle, and crust. The earth’s surface is the layer called the crust which is divided into many segments called plates.


The crust is broken into plates.


Many earthquakes take place along the edge of the oceanic and continental plates which are moved around by the motion of a deeper part of the mantle.


Rock layers are forced upwards creating mountains at the place of plates’ collision.


Where plates diverge, lava emerges from the mantle and cools to form new sections of crust.


Two plates move into each other or slide past each other.


Point of friction


The point within the earth where an earthquake rupture starts is called the hypocenter.


Primary waves (longitudinal or compressional waves) and S-waves (transverse or shear waves)


Surface waves radiable outwards from the epicenter which is the point directly above it on the surface of the Earth.


Particle motion


Love waves, named after British mathematician A.E.H Love, is a surface wave having a horizontal motion that is transverse to the direction the wave is traveling.


The largest earthquake with 9.5 magnitude occurred on 22 May 1960. Its epicenter was near Canete, Chile. The 2004 Indian Ocean earthquake, one of the largest recorded earthquakes which have all been megathrust earthquakes, is one of the deadliest earthquakes in history. In January 2010, the worst 7.0 magnitude earthquake in two centuries struck less than ten miles from the Caribbean city of Port-au-Prices, Haiti, causing damages to Haitian.



Related links:

Surviving Earthquakes — the Basics

Earthquakes – Five Myths

What are Earthquakes ?

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