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| Titel |
Probing the state of stress using early aftershocks |
| VerfasserIn |
Clement Narteau, Peter Shebalin, Matthias Holschneider |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250049900
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| Zusammenfassung |
| An earthquake is usually followed by a sequence of smaller earthquakes called aftershocks. If
the frequency of these aftershocks decreases as a power law over long time scales, it is
obviously not infinite at the end of the mainshock rupture. There is therefore a transient stage
leading to the establishment of the power-law aftershock decay rate. All theoretical
models show that the duration of this transition is potentially an important source of
information to characterize the state of stress along active fault zones. In this context, we
present new theoretical and observational results on the initial behavior of aftershock
sequences.
Using early aftershock statistics and the EAST model, we first concentrate on short-term
earthquake forecasting. In particular, we show how it is possible to use alarm-based
models and earthquake catalogues to produce frequency-based earthquake forecast
models. Thus, we can use alarm-based models to perform all standard comparison
tests installed on interactive platforms developed by CSEP (Collaboratory for the
Study of Earthquake Predictability). The current results show that EAST model
has better predictive power than a stationary reference model based on smoothed
extrapolation of past seismicity. Hence, we conclude that early aftershock decay rate may
be a powerful diagnostic tool for earthquake activity at both, regional and local
scales.
Second, we concentrate on earthquake mechanics as we try to infer the evolution of
tectonic loading on a population of active fault using aftershocks. From Bayesian statistics for
the Modified Omori Law, Î(t) ~ (c + t)-p, and K-means statistics for space-time c maps,
we have access not only to the temporal evolution of the stress state on each fault but also on
the phase portrait of their interactions. Then, we discuss stress exchange mechanisms within
the seismogenic crust. |
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