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| Titel |
Identification of response and timing issues at permanent European broadband stations from automated data analysis |
| VerfasserIn |
Christian Weidle, Riaz Ahmed Soomro, Luigia Cristiano, Thomas Meier |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250078170
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| Zusammenfassung |
| To tackle the ever increasing amount of available broadband seismic data from European
network providers for routine analysis, manual data processing and retrieval of certain
observables (e.g. dispersive traveltimes, polarisation parameters) needs to be replaced
by automated processing tools. We developed an automated routine to measure
inter-station phase velocity curves of fundamental mode Rayleigh and Love waves
by pairwise cross-correlating seismograms from all available permanent stations
in Central and Northern Europe. Making use of path-specific reference models
based on CRUST2.0, only three parameters that control the acceptable bandwidth of
a given observation are required for our automated routine to identify and pick
acceptable dispersion curves. As the measurements are based on the phase difference of
the waveforms at two stations, the measurements are 2Ï ambiguous and we select
the solution that is in general closest to our reference curve. While applying this
routine to the entire dataset, we observe at some stations systematic deviations
from the expected measurement which may not be related to wave propagation
effects. These include timing and response information issues, of the latter most
prominently polarity switches. As we compare wavefields that propagate in both directions
between two stations, both these effects lead to distinct deviative patterns in the
measurements. A polarity problem at one station, for example, leads to dispersion
measurements that are offset from the reference curve with a Ï offset instead of the
expected 2Ï. Timing issues on the other hand lead to symmetric deviations (for the two
propagation directions) that are in general smaller than Ï. Statistical analysis of our
measurements against the expected dispersion curves from our reference models allows us
to construct a map of anomalous stations in Europe. Furthermore, we have also
indications that some instruments may not only have phase but also amplitude issues. |
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