Alessandro Giocoli

Robust identification of periodic behavior in the time dynamics of short seismic series: the case of seismicity induced by Pertusillo Lake, southern Italy

Abstract In this paper, we investigate the time dynamics of the seismicity of the area of the artificial Pertusillo Lake (southern Italy) by using two advanced statistical techniques: the robust periodogram and the singular spectrum analysis. Such methodologies are well suited to unveil the main characteristics (periodicities and long-term trend) of short time series, for which the application of standard statistical techniques fail. Our findings are that the monthly number of earthquakes occurred in the investigated area from 2002 to 2012 reveals the presence of the annual periodicity, which is reasonably linked with the yearly loading/unloading operational cycle of the lake. This indicates that the seismicity of the Pertusillo Lake area is effectively induced by the time-varying water level of the artificial lake. This result from one side sheds light on the nature of the earthquakes occurring in the investigated area as reservoir-induced, but, more generally, from another side suggests a robust manner to investigate the time dynamics of short seismic series.

Integrated near surface geophysics across the active Mount Marzano Fault System (southern Italy): seismogenic hints

Here, we describe an original geophysical multi-method approach applied to the Mount Marzano Fault System. This is one of the most hazardous seismogenic 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 resistivity 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, inexpensive, 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.

Analysis of ground deformation using SBAS-DInSAR technique applied to COSMO-SkyMed images, the test case of Roma urban area

Differential Synthetic Aperture Radar Interferometry (DInSAR) represents a well-established remote sensing technique for the investigation of ground deformation phenomena.Among the DInSAR techniques, the Small BAseline Subset (SBAS) approach exploits ground surface at two mapping scales, low and high resolution, and allows the detection and monitoring of local deformation processes that may affect single buildings or man-made structures in urban areas. This work investigates the capability improvement of the SBAS-DInSAR technique to analyse deformation processes in urban areas by exploiting SAR data acquired by the Cosmo-SkyMed (CSM) constellation in comparison with the results obtained from data of first generation ERS/ENVISAT radar systems of he European Space Agency. In particular, we extracted mean deformation velocity maps as seen by the three different radar systems and, for each coherent pixel, we retrieved the corresponding displacement time series. Our analysis was focused on the Torrino area where independent studies had already revealed significant deformation signals testified by the serious damages on many buildings in the area. Moreover, in order to understand the causes of the CSM observed displacement rates, reaching few cm per year, we also performed a comparative analysis between DInSAR products and independent information derived from electrical resistivity tomography data and geological maps.

Mapping the earthquake-induced landslide hazard around the main oil pipeline network of the Agri Valley (Basilicata, southern Italy) by means of two GIS-based modelling approaches

Abstract This study presents a first-level spatial assessment of the susceptibility to earthquake-induced landslides in the seismic area of the Agri Valley (Basilicata Region, southern Italy), which hosts the largest onshore oilfield and oil/gas extraction and pre-treatment plant in Europe and is the starting point of the 136-km-long pipeline that transports the plant’s products to the refinery located in Taranto, on the Ionian seacoast. Two methodologies derived from the ones proposed by Newmark (Geotechnique 15(2):139–159, 1965) and Rapolla et al. (Eng Geol 114:10–25, 2010, Nat Hazards 61:115–126, 2012. doi:10.1007/s11069-011-9790-z), based on different modelling approaches, were implemented using the available geographic information system tools, which allowed a very effective exploitation of the two models capability for regional zoning of the earthquake-induced landslide hazard. Subsequently, the results obtained from the two models were compared by both visual evaluation of thematic products and statistical correlation analysis of quantitative indices, such as the Safety Index based on the Newmark’s approach and the Susceptibility Index from Rapolla’s model. The comparison showed a general agreement in highlighting the most critical areas. However, some slight differences between the two models’ results were observed, especially where rock materials and steep slopes are prevailing.

Geomorphological Fragility and Mass Movements of the Archaeological Area of “Torre di Satriano” (Basilicata, Southern Italy)

This paper describes the results of geomorphological and stability studies carried out in the archaeological site of Satriano di Lucania (Basilicata, Southern Italy), where an important sanctuary was built during the 4th Century B.C. This study is based on a mutidipliscinarity approach including accurate interpretation of aerial photos, geomorphological and geoelectrical surveys , and stability analyses. A description of the stability condition of the archaeological site with reference to the landslide that affects the sacred complex is provided in this work.

Dynamics of internal and external origin revealed by a single-site magnetotelluric monitoring

A continuously operating magnetotelluric (MT) system was installed in Agri Valley (Southern Italy) by the Institute of Methodologies for the Environmental Analysis (IMAA) for studying the temporal stability of the electric properties of the subsoil. In a previous work, Balasco et al. (2008) analysed 1-year-long dataset evidencing possible source effects. Such effects are deeply investigated in this work considering almost three years monitoring. Two different types of dynamics are revealed: i) a seasonal fluctuation at short sounding periods, and ii) a behaviour linked to the external geomagnetic activity index at high periods.