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Probability of a given‐magnitude earthquake induced by a fluid injection
Author(s) -
Shapiro S. A.,
Dinske C.,
Kummerow J.
Publication year - 2007
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2007gl031615
Subject(s) - magnitude (astronomy) , geology , fluid pressure , maximum magnitude , seismology , tectonics , earthquake magnitude , poromechanics , overpressure , induced seismicity , mechanics , geotechnical engineering , physics , geometry , mathematics , porosity , porous medium , thermodynamics , astronomy , scaling
Fluid injections in geothermic and hydrocarbon reservoirs induce small earthquakes (−3 < M < 2). Occasionally, however, earthquakes with larger magnitudes ( M ∼ 4) occur. We investigate magnitude distributions and show that for a constant injection pressure the probability to induce an earthquake with a magnitude larger than a given value increases with injection time corresponding to a bi‐logarithmical law with a proportionality coefficient close to one. We find that the process of pressure diffusion in a poroelastic medium with randomly distributed sub‐critical cracks obeying a Gutenberg‐Richter relation well explains our observations. The magnitude distribution is mainly inherited from the statistics of pre‐existing fracture systems. The number of earthquakes greater than a given magnitude also increases with the strength of the injection source and the tectonic activity of the injection site. Our formulation provides a way to estimate expected magnitudes of induced earthquakes. It can be used to avoid significant earthquakes by correspondingly planning fluid injections.