Environmental Considerations Associated with Hydraulic Fracturing Operations
by James A. Jacobs, Stephen M. Testa
7Induced Seismicity
7.1 Introduction
It has long been known that humans can cause earthquakes, whether related to dam impoundment, mining activity, geothermal energy development, or hydrocarbon production. These types of earthquakes are commonly referred to as being either induced or triggered. The difference between induced and triggered seismic or earthquake events is considered based on whether the human‐induced stresses are similar to the ambient stress state or are only a small fraction of the ambient level, respectively. In seismology, the term triggered also reflects earthquakes that are caused by previous earthquakes, whether they are naturally occurring or anthropogenic derived.
With the development of shale gas, concern and interest over induced seismicity and identification of the risks associated with well stimulation techniques such as high‐volume hydraulic fracturing have been recognized. Despite this recent attention, anthropogenic‐induced seismicity has been known and reported since at least the 1920s. These events have been associated with a range of activity including controlled explosions associated with the construction and mining industries, impoundments associated with large reservoirs, underground nuclear testing, and certain activities associated with the energy extraction industries (Table 7.1). As of 2017, ~730 anthropogenic projects or projects that have been proposed have induced earthquakes over the past 150 years (Wilson et al. 2017). Recent interest ...