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| Titel |
Mapping of faults activated by the stimulation of the Basel enhanced geothermal system |
| VerfasserIn |
N. Deichmann, T. Kraft, K. F. Evans |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250060821
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| Zusammenfassung |
| High-precision relative location procedures of the stronger seismic events (0.7 < ML
< 3.4), based on cross-correlations of signals recorded by a six-sensor borehole
array and numerous surface stations in the immediate epicentral area, show that
clustering of hypocenters on different spatial scales is a dominant feature of the
microseismicity induced by the stimulation of enhanced geothermal reservoir in Basel. In line
with the fact that many of the observed earthquakes form clusters of similar events,
several focal mechanisms are also nearly identical to each other. A comparison
between the high-precision relative locations of the events within each cluster and the
focal mechanisms often shows a good coincidence of the hypocentral distribution
with one of the nodal planes of the focal mechanism. In some cases, the spatial
extent of the individual clusters is limited to a few meters, which suggests that the
corresponding events represent repeated slip with partial stress drop as pore pressures
increase with time. In other cases, that include some of the stronger events (ML
> 2), the dimension of the individual clusters can amount to several 100 meters,
and the activity within these clusters can extend over several days. Given that the
orientation of many fault segments identified in this way deviates significantly from the
overall orientation of the seismic cloud, these results reveal a complex internal
structure of the flow paths in the rock volume stimulated by the water injection. |
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