Publication Date:
2017-03-11
Description:
We applied a joint survey approach integrating time-domain electromagnetic soundings and single-station ambient vibration surveys in the Middle Aterno Valley (MAV), an intermontane basin in central Italy and the locus of the 2009 L'Aquila earthquake. By imaging the buried interface between the infilling deposits and the top of the pre-Quaternary bedrock, we reveal the 3-D basin geometry and gain insights into the long-term basin evolution. We reconstruct a complex subsurface architecture, characterized by three main depocenters separated by thresholds. Basin infill thickness varies from ~200-300 m in the north to more than 450 m to the southeast. Our subsurface model suggests a strong structural control on the architecture of the basin and highlights that the MAV experienced considerable modifications in its architecture over time. The buried shape of the MAV suggests a recent and still ongoing predominant tectonic control by the NW-SE trending Paganica - San Demetrio Fault System (PSDFS), which cross-cuts older ca. ENE- and NNE- trending extensional faults. Furthermore, we postulate that the present-day arrangement of the PSDFS is the result of the linkage of two previously isolated fault segments. We provide constraints on the location of the southeastern boundary of the PSDFS, defining an overall ~19 km-long fault system. This allows for earthquakes larger than M6.5. This study emphasizes the benefit of combining two easily-deployable geophysical methods for reconstructing the 3-D geometry of a tectonically-controlled basin. Our joint approach provided us with a consistent match between these two independent estimations of the basin substratum depth within 15%.
Print ISSN:
0148-0227
Topics:
Geosciences
,
Physics