Vincenzo Lapenna

2D electrical resistivity imaging of some complex landslides in the Lucanian Apennine chain, southern Italy

We use high-resolution electrical resistivity imaging to delineate the geometry of complex landslides in the Lucanian Apennine chain of southern Italy, to identify the discontinuity between the landslide material and bedrock, and to locate possible surfaces of reactivation. The Lucanian Apennine chain is characterized by high hydrogeological hazard and shows a complete panorama of mass movements. In this area, all typologies of landslides markedly predisposed and tightly controlled by the geostructural characteristics, are found: rotational and translational slides, rototranslational slides, earth and mudflows, as well as deep-seated gravitational slope phenomena with a predominance of rototranslational slides evolving as earthflow slides. Three test sites, characterized by complex geology and a high hydrogeologic hazard, are studied. The Giarrossa and Varco Izzo earthflow slides are located to the west and east of the town of Potenza, whereas the Latronico slide is located close to the town of Latronico....

Mono- and multi-fractal investigation of scaling properties in temporal patterns of seismic sequences

Understanding the statistical properties of time-occurrence series of seismic sequences is considered one of the most pervasive scientific topics. Investigating into the patterns of seismic sequences reveals evidence of time-scaling features. This is shown in the fractal analysis of the 1986–2001 seismicity of three different seismic zones in Italy. Describing the sequence of earthquakes by means of the series of the interevent times, power-law behaviour has been found applying Hurst analysis and detrended fluctuation analysis (DFA), with consistent values for the scaling exponents. The multifractal analysis has clearly evidenced differences among the earthquake sequences. The multifractal spectrum parameters (maximum a0, asymmetry B and width W ), derived from the analysis of the shape of the singularity spectrum, have been used to measure the complexity of seismicity. 2003 Elsevier Ltd. All rights reserved.

The use of electrical resistivity tomographies in active tectonics: examples from the Tyrnavos Basin, Greece

Abstract A 2D Electrical Resistivity Tomography (ERT) survey was carried out in the tectonically active Tyrnavos Basin, Eastern Thessaly, Greece. The principal aims of this research are to test the efficiency of this relatively new geoelectrical technique when applied to the recognition and the geometrical characterisation of active faults and to improve our tectonic knowledge of the investigated area. We therefore carried out several tests performing the geophysical prospecting across morphotectonic scarps or fault traces along which the Late Quaternary tectonic activity is well documented by previous structural, stratigraphic, morphotectonic and palaeoseismological researches. The tests concerned the electrode spacing, the maximum depth of investigation, the quality-to-costs ratio, etc. In a second phase of the survey, we applied this geophysical methodology to specific sites along the major tectonic structures bordering the Tyrnavos Basin, in order to obtain, firstly, a better tectonic knowledge of the area, secondly, to solve particular and local geological problems and, thirdly, to help deciding between ambiguities left unsolved by superficial surveys. Accordingly, numerous ERT with different electrode spacing (from 2 up to 50 m) and depth of investigation (from 0.5 to 120 m) were performed with a dipole-dipole array using a multielectrode system, with 32 electrodes equally spaced along a straight line, for data acquisition. Combining advanced technologies for data acquisition and new tomographic techniques for resistivity data inversion, we obtain a large data-set of high-resolution electrical images of the subsurface across active faults. General and particular results concerning the application of ERT techniques for mapping subsurface active faults are discussed, while advantages and limits in applying this geophysical methodology are emphasised.

A new approach to investigate the correlation between geoelectrical time fluctuations and earthquakes in a seismic area of southern Italy

We propose a new approach to investigate the possible correlation between electrical signals and earthquakes. Good correlation has been found between the spectral power-law exponent of geoelectrical signals and the Hurst exponent of the seismicity of the area investigated. A tendency of both parameters to converge toward unity, typical of self-organized critical dynamics, is evident before the occurrence of the major event recorded in the area during the observation period.

Multifractal fluctuations in seismic interspike series

Multifractal fluctuations in the time dynamics of seismicity data have been analyzed. We investigated the interspike intervals (times between successive earthquakes) of one of the most seismically active areas of central Italy by using the Multifractal Detrended Fluctuation Analysis (MF-DFA). Analyzing the time evolution of the multifractality degree of the series, a loss of multifractality during the aftershocks is revealed. This study aims to suggest another approach to investigate the complex dynamics of earthquakes.

Identifying space–time clustering properties of the 1983–1997 Irpinia–Basilicata (Southern Italy) seismicity

Abstract The fractality of the earthquake sequence (1983–1997) of Irpinia–Basilicata (Southern Italy), one of the most seismically active regions of the Mediterranean area, has been analysed by temporal and spatial fractal tools. The fractal exponent α , estimated by the Allan Factor method, characterises the time-clustering behaviour of the set of earthquakes, while the correlation dimension D C , calculated by means of the correlation integral method, gives information on the space-clustering behaviour of the sequence of seismic events. Analysing the variations of both the parameters, we recognised the presence of a strong space–time clusterisation associated with the major events that occurred in the investigated area.

Depth‐dependent time‐clustering behaviour in seismicity of southern California

Temporal fluctuations in seismicity of southern California have been investigated by means of two methods, the Allan Factor Analysis and the Detrended Fluctuation Analysis, which are used to detect the scaling behaviour of an nonstationary observational time series. Performing the time-clustering analysis varying the depth of the events, we found that the seismicity of the area reveals a tendency toward Poissonian behaviour near the depth ranges 14–16 km.

Multifractal fluctuations in earthquake-related geoelectrical signals

Multifractal fluctuations in the time dynamics of geoelectrical data, recorded in a seismic area of southern Italy, have been analysed. We find that the multifractality of the signal depends mostly on the different long-range properties for small and large fluctuations. Furthermore, we quantitatively characterized the multifractality of the geoelectrical time series, on the basis of the characteristic parameters derived from the multifractal spectrum (maximum α0, asymmetry B and width W) (Shimizu Y, Thurner S and Ehrenberger K 2002 Fractals 10 103). We then analysed the time evolution of the multifractal parameters and we found that the multifractal degree of the signal, revealed by the variation of the width of the multifractal spectrum, is enhanced in association with the occurrence of the largest seismic event. This study aims to suggest another approach to investigate the complex dynamics of geoelectrical signals.

Monofractal and multifractal approaches in investigating scaling properties in temporal patterns of the 1983–2000 seismicity in the western Corinth graben, Greece

Abstract Much recent work has been focused on understanding the statistical properties of time-occurrence series of earthquakes. Investigating into the patterns of seismic sequences reveals evidence of scaling features in temporal behavior. This is shown in the clustering properties of seismicity of the western Corinth graben, Greece from 1983 to 2000. Power-law behavior has been found by means of Allan factor analysis and Fourier spectra for the earthquake sequence, with consistent values for the scaling exponents, that decrease with the threshold magnitude. The analysis of the temporal variation of the scaling exponent, performed with different threshold magnitudes, reveals an enhancing of the clusterization in correspondence to larger events. The multifractal analysis of the temporal distribution of the events has shown a decrease of the intermittent character with the threshold magnitude.

1/fβ Fluctuations and self-similarity in earthquake dynamics: observational evidences in southern Italy

Abstract Recently, it has been determined that many statistical features of earthquakes are scale-invariant with universal values for exponents. The analysis of scaling laws has led to the development of a wide variety of physical models of seismogenesis, involving nonlinear dynamics, and it can be used to better characterize the seismicity pattern. In this work, the presence of scale-invariance properties in the seismicity of a selected area of the Southern Appennine chain is revealed. 1/fβ fluctuations are detected from the analysis of earthquake sequences using the counting statistics and, at the spatial scale, a self-similar structure in the epicentre aggregate is determined by the estimation of its fractal dimension. Finally, correlations between temporal β-exponent, fractal dimension and b-value variations are described.