|Induced seismicity has been observed for decades as a part of human activities, such as oil and gas production, dam building, geothermal energy production, mining and quarrying, underground gas storage, and fluid injection. The study of induced seismicity from these types of activities and others has been ongoing for over 50 years. These studies have had two main objectives: (1) to assess the potential impacts and allay public concern caused by ground motion and (2) to determine the ability to monitor subsurface processes via the induced seismicity. An introductory bibliography to induced seismicity publications is available at the following website: http://www.darlenecypser.com/induceq/induceq.html.
Seismicity occurs when activities in the subsurface perturb the natural existing stress. The majority of seismic events is small in magnitude and produces no observable effects at the surface. There has been no harmful induced seismicity associated with any of the global CCS storage demonstration projects as of February 2011.
However, if the change in stress is large enough, the rock will fracture, releasing seismic energy. Changes in stress less than the fracture stress can cause movement on pre-existing fractures and faults, also releasing seismic energy. Based on understanding local and regional stresses in the Earth’s crust, guidelines have been developed to prevent injection-induced microseismicity. Regulatory agencies limit injection rates and pressures to avoid unintentional hydrofracturing. Microseismic monitoring is often done early in a project to establish operational parameters for injection. Carbon dioxide storage projects would operate under similar guidelines, minimizing concerns about causing earthquakes.
Though there has been no harmful induced seismicity associated with any of the global CCS storage demonstration projects, the operators of these projects acknowledge that care needs to be taken in site selection, design, and the operation of storage sites to assure that induced seismicity does not occur. In particular, the Regional Carbon Sequestration Partnerships (RCSPs) are applying and refining elements of best practice approaches to assure that induced seismicity does not occur.
||CO2 injection is likely to cause an earthquake.
||There has been no induced seismicity associated with any of the global CCS storage demonstration projects to date. The operators of these projects acknowledge that care needs to be taken in site selection, design, and the operation of storage sites to ensure that potentially induced seismicity does not occur.