ORIGINAL PAPER Integrated near surface geophysics across the active Mount Marzano Fault System (southern Italy): seismogenic hints P. A. C. Galli • A. Giocoli • E. Peronace • S. Piscitelli • B. Quadrio • J. Bellanova Received: 8 February 2013 / Accepted: 14 July 2013 Ó Springer-Verlag Berlin Heidelberg 2013 Abstract Here, we describe an original geophysical multi-method approach applied to the Mount Marzano Fault System. This is one of the most hazardous seismo- genic faults of the Apennines (Irpinia, southern Italy), and it was responsible for the 1980, Mw 6.9, earthquake, along with many others before. We carried out electrical resis- tivity tomography (ERT), ground penetrating radar (GPR) measurements, and horizontal-to-vertical spectral ratio (HVSR) microtremor analysis along several common transects designed across the potential and/or certain fault traces. The data obtained from these non-invasive, inex- pensive, expeditious methods mutually integrate with and complement each other, providing a valuable subsurface image of the near surface fault architecture. ERT depicts the general shallow image of the fault zone and of the fault- controlled sedimentary basin, with the depth of the buried bedrock cross-correlated through ambient-noise HVSR results. GPR delineates the very shallow geometry of the fault and of the associated deformation. Coupled with previous paleoseismological studies, these data allow the evaluation of some fault parameters and the precise locating of the fault trace, to aid future paleoseismological investigations aimed at seismic risk reduction programs. Keywords Surface geophysics Á Active faults Á 1980 earthquake Á Southern Italy Á Irpinia Introduction The Mount Marzano Fault System (MMFS; Fig. 1) is one of the few seismogenic structures that has been individu- ated and studied in the extensional southern Apennines domain, the most seismically hazardous region of Italy. Its present activity was manifested dramatically in the 1980 earthquake (Mw 6.9, Io 10 MCS, *3,000 victims), through the 30-km-long surface rupture, with offsets exceeding 1 m (Westaway and Jackson 1984; Pantosti et al. 1993). Nev- ertheless, with this normal fault running mainly through steep, forested slopes (usually 35° dipping), early pale- oseismic trenching has been necessarily focused within flat areas (Piano di Pecore Pantano di San Gregorio Magno; D’Addezio et al. 1991; Pantosti et al. 1993. Figure 1, inset A, sites b and psg, respectively) where the coseismic offset observed in the 1980 earthquake was two times smaller than along the rocky slopes (Peronace et al. 2011). This has probably hampered the complete identification of the consecutive coseismic offsets in the faulted sedimentary record, as confirmed by the preliminary studies in Galli et al. (2011). Therefore, with the aims of (1) using non-invasive methods to identify the best location for future paleoseis- mological excavations; and (2) extending the observations made in the previous paleoseismological trenches to depth, we carried out a kaleidoscopic geophysical campaign Electronic supplementary material The online version of this article (doi:10.1007/s00531-013-0944-y) contains supplementary material, which is available to authorized users. P. A. C. Galli (&) Dipartimento Protezione Civile Nazionale, Rome, Italy e-mail: paolo.galli@protezionecivile.it P. A. C. Galli Á E. Peronace Á B. Quadrio CNR-IGAG, Monterotondo, Rome, Italy A. Giocoli Á S. Piscitelli Á J. Bellanova CNR-IMAA, Tito Scalo, Potenza, Italy A. Giocoli ENEA-Casaccia, Rome, Italy 123 Int J Earth Sci (Geol Rundsch) DOI 10.1007/s00531-013-0944-y