Fault and basin depocentre migration over the last 2?Ma in the L'Aquila 2009 earthquake region, central Italian Apennines

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• 作者：Biagio Giaccio^a ; ^{biagio.giaccio@cnr.it} ; ^{biagio.giaccio@igag.cnr.it} ; Paolo Galli^a ; ^b ; Paolo Messina^a ; Edoardo Peronace^a ; Giancarlo Scardia^a ; Gianluca Sottili^a ; Andrea Sposato^a ; Edi Chiarini^c ; Brian Jicha^d ; Stefania Silvestri^c
• 关键词：L'Aquila 2009 earthquake ; Intermountain basin ; Quaternary sedimentary and tectonic evolution ; Fault migration ; Central Apennines
• 刊名：Quaternary Science Reviews
• 出版年：2012
• 出版时间：21 November, 2012
• 年：2012
• 卷：56
• 期：Complete
• 页码：69-88
• 全文大小：5830 K

文摘

Morphological, stratigraphical and structural investigations integrated with palaeomagnetic and tephrostratigraphic studies and ⁴⁰Ar/³⁹Ar measurements allowed us to define the Quaternary tectonic-sedimentary evolution of the epicentral area of the L'Aquila 2009 earthquake (M_w 6.3). This area roughly matches the Paganica-San Demetrio-Castelnuovo (PSC) intermountain basin filled by a fluvio-lacustrine succession that is variously deformed by normal faults. At its early stage (Early Pleistocene; ca 2?Ma), the basin hosted a lake that was characterised by whitish carbonate silt and mud deposition. Towards the end of the Early Pleistocene, this was partly filled by a south-eastward prograding deltaic system. The south-easternmost portion of the deltaic system was successively abandoned and eroded, while sedimentation of a braided river system developed in a smaller area westwards. Before 780?ka, this fluvio-lacustrine system (the Lower PSC syntheme) ended, and the area underwent erosional and pedogenic processes. These processes continued up to >460?ka, with the onset of fluvial gravel and volcanic-rich silty sand deposition over a narrow area of the south-western PSC basin (an earlier unit of the Upper PSC syntheme, early Middle Pleistocene). Around 460?ka, when most of this area was again subjected to denudational processes, the sedimentation migrated into the previously exposed north-western area of the PSC basin, where fluvial/alluvial sediments were deposited, between ca 460?ka and ca 350?ka (a later unit of the Upper PSC syntheme). Between ca 350?ka and the present, the sedimentation continued uninterrupted in a slight westwards restricted area of the PSC basin (Upper-Late PSC syntheme). The significant contraction of the basin, the shifting of its depocentre, the variation in its geometry and in the spatial distributions and thicknesses of the units constituting the Lower, Upper and Late PSC synthemes, provide evidence for strong tectonic control. This resulted in progressive reduction of the activity of the south-easternmost tectonic structures and parallel migration of the fault activity on the westernmost structures. In this perspective, the fault system responsible for the L'Aquila 2009 earthquake can be seen as the most recent expression of a long-lasting westwards polarised process of tectonic activity transfer.