Earthquake Hazard Overview

An earthquake occurs when a fault suddenly ruptures and releases elastic energy in the form of seismic waves. Rupture begins at the hypocenter (referred to as the epicenter at the surface). Seismic waves can also be generated by volcanic activity, mine blasts, and other natural and manmade sources, but are generally not strong enough to cause damage to the built environment. Magnitude is a measure of the size of an earthquake.

Earthquakes are caused by the slow movements of tectonic plates. Although most earthquakes, especially large ones (magnitude equal to or greater than 8.0), have occurred along plate boundaries, a few strong earthquakes have occurred in plate interiors.

Seismic hazard is the physical phenomenon of an earthquake that can cause damage to the built environment. When an earthquake (fault rupture) occurs, the rupture may continue to the surface and create a surface rupture hazard, which can damage any building or structure built on it. The fault rupture also generates strong seismic waves that propagate along the ground surface and create a ground-motion hazard that can damage or even collapse buildings and other structures.

Surface rupture and ground motion are the primary hazards generated directly by an earthquake. Not all earthquakes generate surface rupture, however; in particular. Ground-motion hazard can affect a large area and is responsible for the majority of the damage from an earthquake. Thus, ground-motion hazard from earthquakes is of major concern.


What is the Kentucky Earthquake Risk?

Kentucky is affected by several seismic zones: the New Madrid and Wabash Valley Seismic Zones to the west and the Eastern Tennessee Seismic Zone to the east.


Link to the State Hazard Mitigation PlanEarthquake Risk Assessment for details, maps and mitigation ideas.