Blog – Disaster Preparedness

Still feeling the aftershocks of earthquakes past

Scientists recently discovered that many recent earthquakes felt in the Midwestern states of the U.S. are really the aftershocks of large-scale earthquakes from centuries ago. The earthquakes on the West Coast, however, may be the aftershocks of earthquakes only dating back a decade or so.

Scientist Mian Liu explains in “Aftershocks happen after a big earthquake because the movement on the fault changed the forces in the earth that act on the fault itself and nearby. Aftershocks go on until the fault recovers, which takes much longer in the middle of a continent.”

The article goes on to explain:

“The two sides of the San Andreas fault move past each other at a speed of about one and a half inches in a year — which is fast on a geologic time scale. This motion ‘reloads’ the fault by swamping the small changes caused by the last big earthquake, so aftershocks are suppressed after about 10 years. The New Madrid faults, however, move more than 100 times more slowly, so it takes hundreds of years to swamp the effects of a big earthquake.”

This recent discovery about earthquakes will help geologists map where the earth is storing a lot of seismic energy so they can better predict when big quakes will hit. Find out more at

There are many steps one can take before, during, and after an earthquake. These natural disasters can cause secondary disasters to happen like fires and water damage from broken pipes. / CC BY 2.0

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