CBS 3 STEM: The Science Behind The Cause Of Earthquakes
PHILADELPHIA (CBS) -- On Sunday, a powerful magnitude 7.8 earthquake struck New Zealand and caused massive infrastructure damage. So what is the science behind the cause of earthquakes?
I talked with Dr. Nicholas Davatzes, Associate Professor in the Earth and Environmental Science Department at Temple University to find out.
'Every once in a while, these plates suddenly slip and that sudden slip event is what we feel as an earthquake,' states Dr. Davatzes.
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These plates are known as tectonic plates. The Earth's crust are comprised of 15 major plates and where they meet we have what are known as faults.
He explains, 'so you want to think of a fault as a break in the Earth where two surfaces are pressed together and are held together in their relative position by friction.'
Just as the friction between our feet and the ground, keeps us upright, sometimes that friction is compromised, and we trip.
Davatzes continues, 'eventually the force of the compression becomes so strong it exceeds that friction and we get a sudden slip and once it starts we release all the stored up energy.'
There are three main types of fault that can cause an earthquake; normal, strike-slip and reverse or thrust.
He demonstrates, 'if you think about two plates, think of them as sorta my hands pressed together, and they can either move apart, they can move along each other or you shove one underneath the other.'
The New Zealand earthquake was due to reverse faulting which, as Davatzes explains, 'is the case when two plates are colliding with each other and one is being thrust underneath the other and actually extends deep hundreds of miles into the Earth, and is this case there was a sudden lurch...'
The size of the Earthquake is a measure of this released energy which is rated by numbers or levels on the Richter scale. The higher on the scale, the greater the shaking and the more damage, by an exponential degree.
Dr. Davatzes says, 'by time you get to a magnitude six is where you start to see more severe damage and what we're dealing with in New Zealand was a 7.8 which is a very large earthquake.'
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There was some concern that this earthquake could trigger a tsunami, but Davatzes says it appears that this earthquake was too deep to have to ruptured the ocean floor and thus no significant tsunami resulted.
