Publication Date:
2017-04-04
Description:
The growing installation of industrial facilities for subsurface exploration
worldwide requires continuous refinements in understanding both the mechanisms by
which seismicity is induced by field operations and the related seismic hazard. Particularly
in proximity of densely populated areas, induced low-to-moderate magnitude
seismicity characterized by high-frequency content can be clearly felt by the surrounding
inhabitants and, in some cases, may produce damage. In this respect we propose a
technique for time-dependent probabilistic seismic-hazard analysis to be used in
geothermal fields as a monitoring tool for the effects of on-going field operations.
The technique integrates the observed features of the seismicity induced by fluid injection
and extraction with a local ground-motion prediction equation. The result of the
analysis is the time-evolving probability of exceedance of peak ground acceleration
(PGA), which can be compared with selected critical values to manage field operations.
To evaluate the reliability of the proposed technique, we applied it to data collected
in The Geysers geothermal field in northern California between 1 September
2007 and 15 November 2010. We show that the period considered the seismic
hazard at The Geysers was variable in time and space, which is a consequence of
the field operations and the variation of both seismicity rate and b-value.We conclude
that, for the exposure period taken into account (i.e., two months), as a conservative
limit, PGA values corresponding to the lowest probability of exceedance (e.g., 30%)
must not be exceeded to ensure safe field operations. We suggest testing the proposed
technique at other geothermal areas or in regions where seismicity is induced, for
example, by hydrocarbon exploitation or carbon dioxide storage.
Description:
Published
Description:
2563–2573
Description:
4.1. Metodologie sismologiche per l'ingegneria sismica
Description:
JCR Journal
Description:
restricted
Keywords:
Seismic hazard
;
Induced seismicity
;
Non-homogeneous poisson model
;
The Gysers geothermal area
;
04. Solid Earth::04.06. Seismology::04.06.11. Seismic risk
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
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