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| Titel |
Optimizing event detection and location in low-seismicity zones: Case study from Western Switzerland |
| VerfasserIn |
Naomi Vouillamoz, Martinus Abednego, Gilles Hillel Wust-Bloch, Jon Mosar |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250126157
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| Publikation (Nr.) |
 EGU/EGU2016-5841.pdf |
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| Zusammenfassung |
| Obtaining robust event catalogs in regions of low-seismicity rate can be time-consuming since quality events are less frequent and sensor coverage is generally sparse. Optimizing event detection and location in such regions is all the more crucial that they host a higher density of sensitive infrastructures. The methodology consists in reprocessing existing data recorded by a permanent network and in boosting the final catalog resolution by temporarily deploying portable sparse mini-arrays in the target area. Sonogram analysis is applied on existing and new datasets to detect waveforms barely emerging from the background noise. A visual interactive event analysis module is used to test for picking simulations, event association, spatial cross-correlation and location ambiguities. It also provides backazimuth and slowness estimations when sparse array data is available. The method was applied to a low-seismicity region in the Western Swiss Molasse Basin where two sparse mini-arrays were temporarily deployed. A 90% increase in earthquake detection was achieved when reprocessing 4 years of available data recorded by two fixed Swiss accelerometers and one broadband station in the target area (2009-2013). Low magnitude estimations were empirically calibrated over four magnitude units, down to -1.7 ML, lowering the existing catalog completeness by close to one magnitude unit. After validating picking and location accuracies with standard residual-based scheme, 174 new events were relocated, illuminating zones of previously undetected microseismic activity. |
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