Earthquakes

Most movement in Earth's crust, known as seismicity, occurs when stress causes a fault or faults in subsurface rocks to slip and release enough energy to generate tremors. The vast majority of earthquakes are instigated naturally where Earth's tectonic plates interact. Earthquake activity in California along the San Andreas Fault—the boundary between the Pacific and North American plates—is a prime example. In places like Kansas, away from plate boundaries, earthquakes are most often associated with subsurface geologic structures and faults.

Earthquake hazard maps show the probability that ground shaking will exceed a certain level over a 50-year period. For example, low-hazard areas have a 2% chance of exceeding a designated low level of shaking. Hazards may vary within an area because localized geology can amplify ground motion.

Although many people have not felt so much as a tremor in Kansas, historic records and newspaper accounts provide evidence of felt earthquakes long before monitoring equipment was available. Beginning in 2013, the state saw an increase in seismic activity, mainly in three south-central counties along the Oklahoma state line. Using new monitoring equipment, KGS researchers helped determine that the uptick was due to human activities, or induced seismicity.

KGS scientists continuously monitor and document seismic activity in Kansas, develop methods used to identify areas at higher risk, and make recommendations to help prevent induced seismicity.