What is Induced Seismicity?
Earthquakes result from the buildup of stress, which is released by sudden motion along a fault. Normally this process occurs on geological timescales, but seismologists have come to understand that this process can be initiated by human activities. For example, the disposal of fluid into basement rock at the Rocky Mountain Arsenal, Colorado, was suspected of inducing earthquakes in the mid-60s. Later, in the mid-70s, an experiment performed at Rangely, Colorado demonstrated that earthquakes were linked to fluid injection and withdrawal at a nearby well. Today, we know that earthquakes can be induced from a variety of human activities such as mining, reservoir impoundment, enhanced geothermal systems, wastewater disposal, carbon sequestration, overburden removal, gas/fluid production, and hydraulic fracturing. Numerous case studies of induced seismicity have been observed worldwide for each of these listed activities. Often the mechanics of induced seismicity is explained as a fault that is critically stressed receiving a small “push,” or change of stress, from human activities that allows the fault to slip prematurely.