Picozzi, Matteo and Oth, A. and Parolai, Stefano and Bindi, D. and De Landro, G. and Amoroso, Ortensia (2017) Accurate estimation of seismic source parameters of induced seismicity by a combined approach of generalized inversion and genetic algorithm: application to The Geysers geothermal area, California. Journal of Geophysical Research: Solid Earth. DOI: https://doi.org/10.1002/2016JB013690
Full text not available from this repository.Abstract
The accurate determination of stress drop, seismic efficiency and how source parameters scale with earthquake size is an important issue for seismic hazard assessment of induced seismicity. We propose an improved non-parametric, data-driven strategy suitable for monitoring induced seismicity, which combines the generalized inversion technique together with genetic algorithms. In the first step of the analysis the generalized inversion technique allows for an effective correction of waveforms for attenuation and site contributions. Then, the retrieved source spectra are inverted by a non-linear sensitivity-driven inversion scheme that allows accurate estimation of source parameters. We therefore investigate the earthquake source characteristics of 633 induced earthquakes (Mw 2-3.8) recorded at The Geysers geothermal field (California) by a dense seismic network (i.e., 32 stations, more than 17.000 velocity records). We find a non-self-similar behavior, empirical source spectra that require an ωγ source model with γ > 2 to be well fit and small radiation efficiency ηSW. All these findings suggest different dynamic rupture processes for smaller and larger earthquakes, and that the proportion of high frequency energy radiation and the amount of energy required to overcome the friction or for the creation of new fractures surface changes with earthquake size. Furthermore, we observe also two distinct families of events with peculiar source parameters that in one case suggests the reactivation of deep structures linked to the regional tectonics, while in the other supports the idea of an important role of steeply dipping faults in the fluid pressure diffusion.
| Item Type: | Article |
|---|---|
| Subjects: | Methodology > Method and procesing > Source parameter estimation Region > USA > California > Geysers Inducing technology > Geothermal energy production |
| Project: | SHEER project > THE GEYSERS: geothermal energy production |