Naked Science Forum
Non Life Sciences => Geology, Palaeontology & Archaeology => Topic started by: Rosita Simbulas Gendrano on 01/05/2016 10:46:57
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Is an Earthquake a silent killer? Yes or No? why?
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Earthquakes are often quite loud
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Is an Earthquake a silent killer?
Most earthquakes release energy that is built up by tectonic plates (https://en.wikipedia.org/wiki/Plate_tectonics) moving against each other.
The energy builds up slowly and silently, then is released suddenly in a (noisy) earthquake.
In some parts of the world (eg Tokyo and California), the fault line between the plates is lubricated, and does frequent small slips. Each of these slips makes a small earthquake - the locals are aware of earthquakes, and (hopefully) build their houses to be safe in an earthquake.
In some other parts of the world (eg Fukushima and Seattle), the fault line is not lubricated and "sticks". This builds up pressure for centuries; the locals aren't aware of earthquakes, and don't build for them. When the force becomes irresistible, there is a devastating earthquake.
In a sense, these "silent" earthquake zones are a silent killer, just waiting.
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There is a more benign form of silent earthquake: one that releases the energy so gradually that it is not felt by humans, only seismographs.
This link shows a map of a cascade of earthquakes propagating along a fault over a period of a few weeks:
http://nwpr.org/post/silent-earthquakes-ripple-under-cascadia
But these silent earthquakes may be building up pressure on the locked segment, which is the real silent killer lurking beneath our feet.
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In typical geologists' style- my answer is "it depends".
There is an old saying among geologists "earthquakes don't kill people, buildings kill people". All else being equal, the human toll from large earthquakes is usually much higher in areas where buildings aren't earthquake resistant (Haiti for example). As ChiralSPO suggested, if you are close enough to an earthquake to feel the ground waves, it will be noisy.
But earthquakes can also cause tsunamis, and tsunamis can travel vast distances and wreak havoc on far-away coastlines without the populace having any earthquake pre-warning. Japanese history refers to the "Orphan Tsunami" of 1700 that killed thousands with no warning and probably was due to a massive Cascadia earthquake off the coast of Oregon/Washington, which was too far away to be felt or heard in Japan. Thankfully, we now have tsunami warning centers around the globe.