PRESSURE MIGRATION ASSESSMENT IN USGS AREAS OF POTENTIALLY INDUCED SEISMICITY

Industrial waste water injected into disposal wells can cross critically stressed faults in the subsurface and induce seismicity. The rate at which this fluid moves through the injection interval, or rate of migration, is dependent on the rate of injection and the hydrogeologic properties of the injection interval and adjacent formations. This research systematically reviews 17 USGS identified potentially induced seismic areas to test if pressure migrations estimates are possible given the currently available data in these locations. Site-specific hydrogeological data in these areas are not prevalently available. A compilation of injection rate values found through state and federal agency data were used to evaluate hydrogeological relationships associated with injection rate and earthquake occurrences. Strong correlations exist between estimated pressure ratio generated at the well and felt earthquake occurrences, providing analytical models for assessing potential seismic hazard. No correlation was found between injection rate and injection interval transmissivities, suggesting a lack of uniform site characterization and injection design based on well hydraulics prior to onset of injection. This research illustrates the need for regional hydrogeologic evaluations in order to assess potential seismic hazards and determining appropriate rates of fluid injection.