Magnetic fabric of Plio-Pleistocene clayey sediments from the footwall of the Avezzano eathquake fault (central Appennines, Italy)

Abstract

The paper reports the results of a study on the anisotropy of the magnetic susceptibility at eight localities along the north-eastern edge of the Fucino basin (Central Italy). This area has been affected by widespread Quaternary tectonics and was struck by the catastrophic 1915 Avezzano earthquake (Ms = 6.9). The aim of this study is to determine the rock magnetic fabric and to investigate its possible origin. The Pliocene-Pleistocene continental clayey sediments exposed at the footwail of the fault responsible for the 1915 earthquake have been studied. The magnetic fabric is typical of undeformed or weakly deformed sediments. Sampling sites have been grouped into three main classes according to their degree of anisotropy. In the most anisotropic sites a nearly horizontal magnetic lineation oriented N302° was identified. This linea-tion is parallel to the trace of the 1915 fault and to the axes of broad flexures in the footwail; it is interpreted as the result of a weak tectonic overprint on the sedimentary-compactional fabric. Its origin is however not well constrained: it may have been produced either during early extensional processes along NE-SW normal faults or may be correlated to the localized deformation within the uplifted footwail of the 1915 seismogenetic structure in response to repeated 1915-like events.