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| Titel |
Automated Master Event Full Waveform Location, An Application to NW Bohemia |
| VerfasserIn |
Sergio Gammaldi, Francesco Grigoli, Simone Cesca, Gilberto Saccorrotti, Josef Horalek |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250089607
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| Publikation (Nr.) |
 EGU/EGU2014-3813.pdf |
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| Zusammenfassung |
| Automated seismic event location is an important task in seismic and microseismic
monitoring operations, where one deals with large datasets of generally weak seismic
events characterized by low signal-to-noise ratios. In such applications, manual
location procedures are time consuming or in some cases not applicable. In the last
years, several automated location method based on waveform stacking have been
developed and successfully applied to different datasets recorded at local and regional
distances. These methods are noise robust and do not require manual phase picking and
identification. On the other hand, they require a good knowledge of the seismic
velocity model. We focus here on the location approach developed by Grigoli et
al. (2013, 2014) based on the stacking of short time average to long time average
ratios (STA/LTA) traces of characteristic functions, using both P and S phases.
For the P phase, we use the STA/LTA traces of the vertical energy function. For
the S phase, the method performance was improved using a second characteristic
function, based on the principal component analysis technique. Here, we further
extend this method using a master event approach. Characteristic functions are
stacked using travel time tables, which are derived from theoretical travel time
differences with respect to a reference location, and observed arrival times for a
reference event. Our new relative location method presents several benefits, which
improve the location accuracy. First, it accounts for phase delays, due to local site
effects, e.g. surface topography or variable sediment thickness. Second, theoretical
velocity model are only used to estimate travel time within the source volume, and not
along the entire source-sensor path. After testing the method with synthetic data, we
applied it to real data related to earthquakes in NW Bohemia. This work has been
funded by the German BMBF “Geotechnologien” project MINE (BMBF03G0737A). |
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