Probability of a given-magnitude earthquake induced by a fluid injection
Article first published online: 27 NOV 2007
Copyright 2007 by the American Geophysical Union.
Geophysical Research Letters
Volume 34, Issue 22, November 2007
How to Cite
2007), Probability of a given-magnitude earthquake induced by a fluid injection, Geophys. Res. Lett., 34, L22314, doi:10.1029/2007GL031615., , and (
- Issue published online: 27 NOV 2007
- Article first published online: 27 NOV 2007
- Manuscript Accepted: 22 OCT 2007
- Manuscript Revised: 10 OCT 2007
- Manuscript Received: 14 AUG 2007
- earthquake probability
 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.