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| Titel |
Slip rate variability over the Holocene period in the middle Aterno fault system (Italy), retrieved from in situ 36Cl cosmogenic nuclide dating of exhumed fault-plane. |
| VerfasserIn |
Jim Tesson, Lucilla Benedetti, Stefano Pucci, Fabio Villani, Didier Bourlès, Karim Keddadouche, Georges Aumaître |
| 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 |
250134648
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| Publikation (Nr.) |
 EGU/EGU2016-15392.pdf |
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| Zusammenfassung |
| Numerous numerical modeling studies have described and quantified non-stochastic
spatio-temporal variations of earthquake occurrences within fault-networks, such as temporal
clustered earthquakes or fault synchronization. However, very few long-enough
paleoseismological and geological records are available to test those models against
well-constrained dataset and thus account for such variability in the fault behavior.
The prerequisites for improving our understanding of fault-rupture processes and
thus our capacity to better assess seismic hazard are to acquire paleoseismological
records that enable to derive both long-term slip-rate and short-term variability, on a
large population of faults and/or within a fault system. These conditions met in
Central Apennines, an extensional province where substantial paleoseismological
dataset accurately described the Holocene seismic history of a dense network of
normal faults. In this study we use 36Cl in situ cosmogenic nuclide to retrieve the
seismic history of 3 faults belonging to the Middle Aterno fault system, from north to
south: the Bazzano fault, the Roccapreturo fault and the Sulmona fault, a portion
of which ruptured during the 2009 L’Aquila earthquake in Italy. We use a new
modeling approach to determine the age and slip of past seismic events from the 36Cl
concentration profiles. This model is based on an inverse approach and uses an
optimization algorithm enabling all the parameter space (number of events, age and slip of
events, pre-exposure) to be explored without a priori constraints (see Tesson et al. in
session TS4.2/NH4.16/SM3.8). Using this new approach, we precisely determine the
slip events occurrences over the Holocene period of those three faults. The results
indicate that the three studied faults have ruptured between 4.5 and 5.5 ka, while the
southernmost part of the system has also ruptured between at 1.5-3 ka (Sulmona fault and
southern segment of Roccapreturo). Those results are in agreement with the ages of
seismic events retrieved from trenching paleoseismological studies performed on fault
segments also belonging to the Middle Aterno fault system. Those results thus suggest
that the 50 km long fault-system (from the Paganica fault to the Sulmona fault)
entirely ruptured in a sequence of events between 4.5 and 5.5 ka. During these
periods of intense seismic activity, the associated slip-rate increases up to 3 mm/yr
on those faults. Those results shed new light about the seismogenic potential of
this fault-system and bring crucial data for the seismic hazard assessment of this
area. |
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