Clear and Simple Illustration of Mechanism to Explain Earthquakes in the Central and Eastern United States

This is a clear and simple illustration (adapted from the South Carolina Earthquake Education and Preparedness Program) of the commonly accepted “ancient zones of weakness” model for the cause of earthquakes in the Central and Eastern United States (and other “intraplate” regions far from plate boundaries). According to this model, preexisting faults and/or other geological features formed during ancient geological episodes persist in the intraplate crust, and, by way of analogy with plate boundary seismicity, earthquakes occur when the present-day stress is released along these zones of weakness.

Also see:

Why Does the Earth Quake in New England? and South Carolina Earthquake Education and Preparedness Program