bluuebunny/crossref_metadata_2025 huggingface dataset:
Landslide susceptibility assessment considering landslide typology. A case study in the area north of Lisbon (Portugal)
Authors: Zêzere J. L.
Published: April 2010

Abstract. The aim of the study is to confirm the importance of discriminate different types of slope movements for a better landslide susceptibility evaluation. The study was applied to the sample area of Calhandriz (11.3 km2) in the area North of Lisbon. Sixty shallow translational slides, 23 deeper translational movements and 19 rotational movements were selected for statistical analysis. Landslide susceptibility assessment was achieved using a data-driven approach: the Information Value Method (Yin and Yan, 1988). The method was applied both to the total set of considered landslides and to each type of slope movement, and the obtained success rates for the highest susceptibility classes are higher in the latter case. The different types of landslides are not equally conditioned by the considered instability factors. Information scores are higher for lithology, concordance between slope aspect and dip of the strata, and slope angle, respectively, for rotational movements, translational movements and shallow translational slides. The information value of the variables "presence of artificial cut (roads)" and "presence of fluvial channel" is systematically high for the three types of slope movement, pointing out the importance of both anthropogenic influence and bank erosion on slope instability in the study area. Different types of landslides have neither the same magnitude nor equal damaging potential. Furthermore, technical strategies to mitigate landsliding also depend on landslide typology. These are additional reasons to discriminate between different types of slope movements when assessing landslide susceptibility and hazard.
The use of NOAA/AVHRR satellite data for monitoring and assessment of forest fires and floods
Authors: Domenikiotis C. , Loukas A. , Dalezios N. R.
Published: April 2010

Abstract. The increasing number of extreme natural phenomena, which are related to the climate variability and are mainly caused by anthropogenic factors, escalate the frequency and severity of natural disasters. Operational monitoring of natural hazards and assessment of the affected area impose quick and efficient methods based on large-scale data, readily available to the agencies. The growing number of satellite systems and their capabilities give rise to remote sensing applications to all types of natural disasters, including forest fires and floods. Remote sensing techniques can be used in all three aspects of disaster management viz: forecasting, monitoring and damage assessment. The purpose of this paper is to highlight the importance of satellite remote sensing for monitoring and near-real time assessment of the affected by forest fires and floods areas. As a tool, two satellite indices are presented, namely the Normalized Difference Vegetation Index (NDVI) and the Surface Temperature (ST), extracted by the meteorological satellite NOAA/AVHRR. In the first part of the paper, a review of utilized techniques using NDVI and ST is given. In the second part, the application of various methodologies to three case studies are presented: the forest fire of 21–24 July 1995 in Penteli Mountain near Athens and 16 September 1994 in Pelion Mountain in Thessaly region, central Greece, and finally the flood of 17–23 October 1994 in Thessaly region, central Greece. For all studies the NDVI has been utilized for hazard assessment. The method of ST has been applied to the flood event in Thessaly, for the estimation of the areal extent of the floods. As emerged from the studies, remote sensing data can be decisive for monitoring and damage assessment, caused by forest fires and floods.
Exalting in atmospheric tides as earthquake precursor
Authors: Biagi P. F. , Piccolo R. , Capozzi V. , Ermini A. , Martellucci S. , Bellecci C.
Published: April 2010

Abstract. During February–March 1998, we observed a significant increase (6–8 dB) in the electric field of the CZE (f = 270 kHz, Czech Republic) broadcasting station at a site named AS and located in central Italy. On 13 March 1998 an earthquake (M = 5.2) occurred in Slovenia, starting a strong seismic crisis (M = 6.0 on 12 April, M = 5.1 on 6 May). The distances of the epicentres from the radio receiver were over 400 km, but the epicentres are located in a zone that is in the middle of the CZE-AS path. Previously, we advanced the hypothesis that the increase of radio-signal electric field detected could be a precursor of the Slovenia seismic crisis. At the purpose to precise the connection between this radio anomaly and the preparatory phase of the earthquakes, we analysed in detail the data collected. At first we carried out a FFT on the data and clear harmonic components with period 0.5d, 1d, 14d, 28d and 365d were revealed. These periods are characteristic of gravity tides and therefore, it seems reasonable to consider the previous harmonics in the electric field of the radio signal as components related to tides of the atmosphere, assuming as tides of the atmosphere only the linear action of gravity tides on atmosphere. Then, we carried out band pass filters on our data and we discovered that the February–March 1998 increase is mainly related to an exalting of the harmonics with period 0.5d, 1d, 14d and 28d, i.e. of the (semi)monthly and (semi)diurnal atmospheric tidal components in the radio signal. Supposing that this exalting is produced by a corresponding exalting of the atmospheric tides we propose a model able to explain the production of such an effect during the preparatory phase of the Slovenia earthquakes.
Thermal anomalies and fluid geochemistry framework in occurrence of the 2000-2001 Nizza Monferrate seismic sequence (northern Italy): Episodic changes in the fault zone heat flow or chemical mixing phenomena?
Authors: Quattrocchi F. , Favara R. , Capasso G. , Pizzino L. , Bencini R. , Cinti D. , Galli G. , Grassa F. , Francofonte S. , Volpicielli G.
Published: April 2010

Abstract. The paper discusses the correlation between the heating of shallow groundwater over a 10 × 20 km wide area close to the town of Nizza Monferrato (Piemonte Region, Northern Italy) and the concomitant local seismic sequences during the period August 2000 – July 2001. The first seismic sequence started on 21 August 2000 with a Ml = 5.2 earthquake. Within few hours, the local authorities received calls alerting that the groundwater temperature rose from 10 to 30°C in many shallow wells. Our geochemical experimental data and the geological-seismotectonic framework do not allow the hypothesis of simple fluid mixing between the thermal reservoir of Acqui Terme and the Nizza-Monferrato shallow groundwater to explain the observed thermal anomalies. On the other hand, we invoke more complex processes such as frictional heating, mechano-chemistry, fault-valve mechanism, adiabatic decompression and hydrogeologically driven heat flow i.e., thermal effects due to variations of basin-scale permeability field. All these processes are able to transmit heat to the surface and to generate a transient incremental heat flow better than the mass transfer occurring typically when fluids from different reservoirs mix.
Variability of sporadic E-layer semi transparency (foEs-fbEs)with magnitude and distance from earthquake epicenters to vertical sounding stations
Authors: Liperovskaya E. V. , Pokhotelov O. A. , Hobara Y. , Parrot M.
Published: April 2010

Abstract. Variations of the Es-layer semi transparency co-efficient were analyzed for more than 100 earthquakes with magnitudes M > 4 and depths h < 100 km. Data of mid latitude vertical sounding stations (Kokubunji, Akita, and Yam-agawa) have been used for several decades before and after earthquake occurrences. The semi-transparency coefficient of Es-layer X = (foEs – fbEs)/fbEs can characterize, for thin layers, the presence of small scale plasma turbulence. It is shown that the turbulence level decreases by ~ 10% during three days before earthquakes probably due to the heating of the atmosphere. On the contrary, the turbulence level increases by the same value from one to three days after the shocks. For earthquakes with magnitudes M > 5 the effect exists at distances up to 300 km from the epicenters. The effect could also exist for weak (M ~ 4) and shallow (depth < 50 km) earthquakes at a distance smaller than 200 km from the epicenters.
Simulating debris flows through a hexagonal cellular automata model: SCIDDICA S3–hex
Authors: D’Ambrosio D. , Di Gregorio S. , Iovine G.
Published: April 2010

Abstract. Cellular Automata (CA) represent a formal frame for dynamical systems, which evolve on the base of local interactions. Some types of landslide, such as debris flows, match well this requirement. The latest hexagonal release (S3–hex) of the deterministic model SCIDDICA, specifically developed for simulating debris flows, is described. For CA simulation purposes, landslides can be viewed as a dynamical system, subdivided into elementary parts, whose state evolves exclusively as a consequence of local interactions within a spatial and temporal discretum. Space is the world of the CA, here constituted by hexagonal cells. The attributes of each cell ("substates") describe physical characteristics. For computational reasons, the natural phenomenon is "decomposed" into a number of elementary processes, whose proper composition makes up the "transition function" of the CA. By simultaneously applying this function to all the cells, the evolution of the phenomenon can be simulated in terms of modifications of the substates. SCIDDICA S3–hex exhibits a great flexibility in modelling debris flows. With respect to the previous releases of the model, the mechanism of progressive erosion of the soil cover has been added to the transition function. Considered substates are: altitude; thickness and energy of landslide debris; depth of erodable soil cover; debris outflows. Considered elementary processes are: mobilisation triggering and effect (T1), debris outflows (I1), update of landslide debris thickness and energy (I2), and energy loss (T2).  Simulations of real debris flows, occurred in Campania (Southern Italy) in May 1998 (Sarno) and December 1999 (San Martino V.C. and Cervinara), have been performed for model calibration purposes; some examples of analysis are briefly described. Possible applications of the method are: risk mapping, also based on a statistical approach; evaluating the effects of mitigation actions (e.g. stream deviations, topographic alterations, channelling, embankments, bridges, etc.) on flow development.
Historical floods in the Dutch Rhine Delta
Authors: Glaser R. , Stangl H.
Published: April 2010

Abstract. Historical records provide direct information about the climatic impact on society. Especially great natural disasters such as river floods have been for long attracting the attention of humankind. Time series for flood development on the Rhine branches Waal, Nederrijn/Lek and IJssel in the Dutch Rhine Delta are presented in this paper. In the case of the Waal it is even possible to compare historical flood frequencies based on documentary data with the recent development reconstructed from standardized instrumental measurements. In brief, we will also discuss various parameters concerning the structure of the flood series and the "human dimension" of natural disaster, i.e. the vulnerability of society when facing natural disasters.
Seismic triggering of landslides. Part B: Simulation of dynamic failure processes
Authors: Havenith H.-B. , Strom A. , Calvetti F. , Jongmans D.
Published: April 2010

Abstract. From field observations it is possible to establish correlations between geological conditions and landslide occurrence. However, in general, it is difficult to assess the affect of individual factors on slope instability because of their mutual interaction. In addition, the dynamic effect of propagating seismic waves significantly increases the complexity of the slope stability problem. Wave diffraction, reflection and focusing effects are dependent on local geological conditions and make it difficult to analyse dynamic sliding mechanisms using field observations alone. As a consequence, in order to examine the influence of various geological and seismic factors on slope movements, it is often necessary to produce numerical models. This paper describes the results of such models as applied to two case studies in Kyrgyzstan: the Ananevo rockslide, located in granite, and the Suusamyr debris slump-flow, situated within soft sediments (see Part A: Havenith et al., 2003). Discrete element modelling (UDEC), adapted both to the discontinuous character of fractured rock and to the heterogeneity of layered mediums, was used. This permitted simulation of deformation mechanisms, including seismically induced bending, block tilting, and slip. Particular attention was paid to the interaction between deformation mechanisms, site-specific amplification effects, and subsurface structure.
Analysis of natural neutron flux in a seismically active zone
Authors: Ostapenko V. F. , Krasnoperov V. A.
Published: April 2010

Abstract. In a seismically active zone in the near Almaty area (Kazakhstan) since 1996 observations of variations of a natural neutron flux have been conducted. Sometimes the neutron flux rises sharply within the one-hour interval in comparison with the background. It occurs on the eve of activation of seismic processes. Increase of the neutron flux level had taken place from 1 h to 10 days prior to earthquakes. It is also indicated a tendency of growth of the anomaly level in accordance with the growth of energetic class of the subsequent earthquake. A character of connection between the neutron flux and earthquakes is still not clear. It is proposed that the neutron flux anomalies caused by variations of cosmic radiation intensity under action of fluxes of solar material, which is burst into interplanetary space (solar wind) during solar flares. Energy of the solar wind transferred to Earth puts into action a trigger mechanism of the process of initiation of earthquakes at those places where conditions have already been prepared for them. The neutron flux anomalies can be used as substantial additional information for classical geophysical methods of short-term earthquake prediction.
Distributed modelling of shallow landslides triggered by intense rainfall
Authors: Crosta G. B. , Frattini P.
Published: April 2010

Abstract. Hazard assessment of shallow landslides represents an important aspect of land management in mountainous areas. Among all the methods proposed in the literature, physically based methods are the only ones that explicitly includes the dynamic factors that control landslide triggering (rainfall pattern, land-use). For this reason, they allow forecasting both the temporal and the spatial distribution of shallow landslides. Physically based methods for shallow landslides are based on the coupling of the infinite slope stability analysis with hydrological models. Three different grid-based distributed hydrological models are presented in this paper: a steady state model, a transient "piston-flow" wetting front model, and a transient diffusive model. A comparative test of these models was performed to simulate landslide occurred during a rainfall event (27–28 June 1997) that triggered hundreds of shallow landslides within Lecco province (central Southern Alps, Italy). In order to test the potential for a completely distributed model for rainfall-triggered landslides, radar detected rainfall intensity has been used. A new procedure for quantitative evaluation of distributed model performance is presented and used in this paper. The diffusive model results in the best model for the simulation of shallow landslide triggering after a rainfall event like the one that we have analysed. Finally, radar data available for the June 1997 event permitted greatly improving the simulation. In particular, radar data allowed to explain the non-uniform distribution of landslides within the study area.
Dynamic structure and data sets of a GIS database for geological riskanalysis in the Azores volcanic islands
Authors: Gaspar J. L. , Goulart C. , Queiroz G. , Silveira D. , Gomes A.
Published: April 2010

Abstract. Geological hazards in the Azores archipelago include earthquakes, volcanic eruptions, degassing phenomena and landslides, being the cause of thousands of deaths and severe damage and loss. To reduce the impact of future events it is necessary to improve the emergency response and reinforce land-use planning, and this has given rise to the development of AZORIS, a GIS database for risk analysis in the Azores. At present this computer-based system comprises nine main dynamic data sets where elemental, monitoring and historical data are grouped in layers of first and second order. The logical structure of the database was conceived in order to facilitate interactivity between data sets and to guarantee the evolution of the system, as determined by the input and the generation of new and more detailed information. Archive organization was designed taking into account regional and local aspects of geological hazard. In order to ensure consistency of the database and the quality of the data within it, an internal process of validation was included.
Social and economic factors of the natural risk increasing: estimation of the Russian regions
Authors: Petrova E.
Published: April 2010

Abstract. This study is an attempt to assess quantitatively social and economic factors that determine vulnerability of Russian regions to natural risk, to trace the space differences of the considered factors, and to group the regions by their similarity. In order to indicate the regional differences in social and economic development, equipment condition, dangerous substances accumulation, and social trouble four the most suitable parameters were estimated, including the per capita production of Gross Regional Product (GRP), capital consumption, volume of total toxic waste, and crime rate. Increase of the first parameter causes vulnerability reducing, the increase of the last three causes its increasing. Using multidimensional cluster analysis five types of regions were found for Russia according to similarity of the considered parameters. These types are characterized with higher value of a single (rarely two) chosen parameter, which seems to be sufficient enough to affect natural risks increasing in these regions in near future. Only few regions belonging to the fifth type proved to have rather high value of GRP and relatively low values of the other parameters. The negative correlation was found between a number of natural disasters (ND) and the per capita GRP in case when some parameters reached anomalously high value. The distinctions between regions by prevailing different parameters, which result in natural risk increasing, help risk management to find directions where to focus on.
Development of avalanche risk between 1950 and 2000 in the Municipality of Davos, Switzerland
Authors: Fuchs S. , Bründl M. , Stötter J.
Published: April 2010

Abstract. In recent years, risk assessment has become increasingly important for the protection of settlements against natural hazards because the public authorities have to economise their budgets and therefore to legitimate their investments. To quantify risk, information is needed on both, recurrence intervals of the potentially damaging natural processes and on the associated damage potential. In the past, high efforts were undertaken to assess the former, while the latter was almost ignored. The aim of this study was to determine the development of the avalanche risk in the inhabited areas of the municipality of Davos, canton of Grisons, Switzerland, for the period between 1950 and 2000. The extent of avalanche prone areas was quantified using the numerical avalanche model AVAL-1D and the current legal hazard maps. The damage potential was quantified by the number and reinstatement values of buildings and by the number of persons per building. It has been demonstrated that, contrary to the frequently expressed statement that the vulnerability of communities has increased, the risk for this settlement in fact decreased substantially. This can mainly be attributed to the realisation of mitigation measures, such as defence structures in avalanche starting zones. The only exception regarding the development of risk was in the category of residential buildings, were an increase in risk was already detectable at medium recurrence intervals. This is remarkable because methods of land use planning, such as hazard mapping, are intended to protect residential buildings from the impact of hazardous processes. However, general statements referring to a larger area (region, country) might be difficult to make, since small-scale disparities have a very important influence on the diversification of risk and risk management. Furthermore, it has to be emphasized that the results are highly dependent on the assumptions made in this study.
Local models for rainstorm-induced hazard analysis on Mediterranean river-torrential geomorphological systems
Authors: Diodato N.
Published: April 2010

Abstract. Damaging hydrogeomorphological events are defined as one or more simultaneous phenomena (e.g. accelerated erosions, landslides, flash floods and river floods), occurring in a spatially and temporal random way and triggered by rainfall with different intensity and extent. The storm rainfall values are highly dependent on weather condition and relief. However, the impact of rainstorms in Mediterranean mountain environments depend mainly on climatic fluctuations in the short and long term, especially in rainfall quantity. An algorithm for the characterisation of this impact, called Rainfall Hazard Index (RHI), is developed with a less expensive methodology. In RHI modelling, we assume that the river-torrential system has adapted to the natural hydrological regime, and a sudden fluctuation in this regime, especially those exceeding thresholds for an acceptable range of flexibility, may have disastrous consequences for the mountain environment. RHI integrate two rainfall variables based upon storm depth current and historical data, both of a fixed duration, and a one-dimensionless parameter representative of the degree ecosystem flexibility. The approach was applied to a test site in the Benevento river-torrential landscape, Campania (Southern Italy). So, a database including data from 27 events which have occurred during an 77-year period (1926-2002) was compared with Benevento-station RHI(24h), for a qualitative validation. Trends in RHIx for annual maximum storms of duration 1, 3 and 24h were also examined. Little change is observed at the 3- and 24-h duration of a storm, but a significant increase results in hazard of a short and intense storm (RHIx(1h)), in agreement with a reduction in return period for extreme rainfall events.
Estimation of the seismic hazard parameters for various sites in Greece using a probabilistic approach
Authors: Banitsiotou I. D. , Tsapanos T. M. , Margaris V. N. , Hatzidimitriou P. M.
Published: April 2010

Abstract. The probabilistic approach that was recently introduced by Kijko and Graham (1998,1999) was applied for the estimation of seismic hazard for various sites in Greece in terms of peak ground acceleration (PGA) and peak ground velocity (PGV). These sites represent geographically cities of Greece among which are the capital of Greece and some others with high, intermediate and low seismicity. The approach allows the use of earthquake catalogues with incomplete reported historical and complete instrumental data, the consideration of different magnitude thresholds, and the incorporation of magnitude uncertainties. One of the advantages of the method is that it does not require any determination of seismic zones. The estimated values of PGA for return periods of 476 years were grouped in 4 categories, the same ones used in the seismic hazard map for the New Seismic Code of Greece. Comparison results were quite interesting and very encouraging concerning the reliability of this probabilistic approach.
Critical conditions of bed sediment entrainment due to debris flow
Authors: Papa M. , Egashira S. , Itoh T.
Published: April 2010

Abstract. The present study describes entrainment characteristics of bed material into debris flow, based on flume tests, numerical and dimensional analyses. Flume tests are conducted to investigate influences of bed sediment size on erosion rate by supplying debris flows having unsaturated sediment concentration over erodible beds. Experimental results show that the erosion rate decreases monotonically with increase of sediment size, although erosion rate changes with sediment concentration of debris flow body. In order to evaluate critical condition of bed sediment entrainment, a length scale which measures an effective bed shear stress is introduced. The effective bed shear stress is defined as total shear stress minus yield stress on the bed surface. The results show that critical entrainment conditions can be evaluated well in terms of Shields curve using the effective bed shear stress instead of a usual bed shear stress.
Magnitude and frequency of landslides triggered by a storm event, Loughborough Inlet, British Columbia
Authors: Guthrie R. H. , Evans S. G.
Published: April 2010

Abstract. One hundred and one landslides were documented across 370km2 following a rainstorm that swept the British Columbia coastline on 18 November 2001. Despite the regional nature of the storm, the landslides were spaced close together, even within the study area. Landslide clustering is attributed to high intensity storm cells too small to be recorded by the general hydrometric network. The evidence nicely corroborates previous historical studies that reached similar conclusions, but against which there was no modern analog analyzed for coastal British Columbia. Magnitude-cumulative frequency data plotted well on a power law curve for landslides greater than 10000m2, however, below that size several curves would fit. The rollover effect, a point where the data is no longer represented by the power law, therefore occurs at about 1.5 orders of magnitude higher than the smallest landslide. Additional work on Vancouver Island has provided evidence for rollovers at similar values. We propose that the rollover is a manifestation of the physical conditions of landslide occurrence and process uniformity. The data was fit to a double Pareto distribution and P-P plots were generated for several data sets to examine the fit of that model. The double Pareto model describes the bulk of the data well, however, less well at the tails. For small landslides (<650m2) this may still be a product of censoring. Landscape denudation from the storm was averaged over the study area and equal to 2mm of erosion. This is more than an order of magnitude larger than the annual rate of denudation reported by other authors for coastal British Columbia, but substantially less than New Zealand. The number is somewhat affected by the rather arbitrary choice of a study area boundary.
Lightning in the eastern Alps 1993-1999, part I: Thunderstorm tracks
Authors: Bertram I. , Mayr G. J.
Published: April 2010

Abstract. Thunderstorm tracks in the eastern Alps for the summers of 1993-1999 are investigated based on lightning data. The tracking method consists of three steps. Step one filters weak storms. Step two fixes the positions of the single cells, which are then connected. The wind at 700hPa, which approximates the steering level of the thunderstorms, is used to distinguish between six weather patterns. Maps including all discovered tracks are discussed for each flow type. While locations from which thunderstorms originate are almost similar, the track patterns are distinct for each flow type. Main initiation areas are mountain ranges of moderate altitude (≈2.5km MSL) from where most of the tracks lead into flat areas.
A direction finding technique for the ULF electromagnetic source
Authors: Surkov V. V. , Molchanov O. A. , Hayakawa M.
Published: April 2010

Abstract. A technique of direction finding is proposed, which can be applied to the magnetic-dipole type source located in the conductive ground. To distinguish a weak ULF source signal from the natural noise a network of multicomponent magnetometers is supposed to be used. The data obtained by the ground-based stations is processed in such a way that a set of partial derivatives of the magnetic perturbations due to the source are found. Comparing these derivatives with theoretical formulae makes it possible, in principle, to find the ULF source parameters such as the distance and amplitude. Averaging the data and a special procedure are proposed in order to exclude random fluctuations in the magnetic moment orientation and to avoid hydrogeological and other local factors.
Use of resistivity measurements to detect urban caves in Mexico City and to assess the related hazard
Authors: Antonio-Carpio R. G. , Pérez-Flores M. A. , Camargo-Guzmán D. , Alanís-Alcantar A.
Published: April 2010

Abstract. In the XIX century when Mexico City was much smaller than at present, there was non-regulated mining of building materials in a region of tuffs northwest of the city in an inhabited countryside. With the growth of the city during the XX century, this region was increasingly populated and in the 1970's many two-level bricks houses were built, without regard for underground caves created by the earlier extractions. Some ground sinkings in adjacent areas alarmed the residents who now are worried about this permanent hazard. An association of residents contracted a private company for a geophysical study in order to know the distribution of the caves. Resistivity measurements were taken in the area to detect the caves in order to alert city authorities. Resistivity data along most of the streets were collected with the array pole-dipole that consisted of three grounded electrodes. We performed 2-D dimensional inversions to the data in order to get a 2-D resistivity image of every street. This is similar to a resistivity cross-section of the ground but obtained from the inversion of pole-dipole and Schlumberger resistivity data simultaneously. Using the information of previous drills we modified our programming code in order to perform constrained inversion and to get more accurate resistivity models in agreement with the drills. From the resistivity models obtained for every street it was possible to produce a map which shows the horizontal distribution of the resistive bodies at a depth of 12m. These resistive bodies show coherent alignments that seem to correspond with a distributions of interconnected caves or tunnels used for extracting the sandy-tuffs. From these kind of interpretation method it was intended to get a more accurate horizontal distribution of the excavated areas in order to better know the urbanized area affected and lead the authorities to remedy the area with refill material.
A neuro-fuzzy approach to the reliable recognition of electric earthquake precursors
Authors: Konstantaras A. , Varley M. R. , Vallianatos F. , Collins G. , Holifield P.
Published: April 2010

Abstract. Electric Earthquake Precursor (EEP) recognition is essentially a problem of weak signal detection. An EEP signal, according to the theory of propagating cracks, is usually a very weak electric potential anomaly appearing on the Earth's electric field prior to an earthquake, often unobservable within the electric background, which is significantly stronger and embedded in noise. Furthermore, EEP signals vary in terms of duration and size making reliable recognition even more difficult. An average model for EEP signals has been identified based on a time function describing the evolution of the number of propagating cracks. This paper describes the use of neuro-fuzzy networks (Neural Networks with intrinsic fuzzy logic abilities) for the reliable recognition of EEP signals within the electric field. Pattern recognition is performed by the neural network to identify the average EEP model from within the electric field. Use of the neuro-fuzzy model enables classification of signals that are not exactly the same, but do approximate the average EEP model, as EEPs. On the other hand, signals that look like EEPs but do not approximate enough the average model are suppressed, preventing false classification. The effectiveness of the proposed network is demonstrated using electrotelluric data recorded in NW Greece.
Principal component analysis of geoelectrical signals measured in the seismically active area of Basilicata Region (southern Italy)
Authors: Telesca L. , Colangelo G. , Hattori K. , Lapenna V.
Published: April 2010

Abstract. Geoelectrical fluctuations are the end product of several geophysical phenomena. In particular geoelectrical signals measured in seismically active areas can be attributed to stress and strain changes, associated with earthquakes. The complexity of this problem has suggested the development of advanced statistical methods to investigate the heterogeneous nature of these fluctuations. In this paper we analysed the time dynamics of short-term variability of geoelectrical field measured at Giuliano station, located in Basilicata Region, one of the most seismically active areas of southern Italy. We applied the principal component analysis (PCA). The analysis has shown earthquake precursory patterns in the daily variation of the principal components, revealing that the PCA approach is promising for monitoring seismic areas.
Magnitude and sign scaling in power-law correlated geoelectrical time series measured in southern Italy
Authors: Telesca L. , Lapenna V.
Published: April 2010

Abstract. Recently, it has been proposed a new method to investigate the linear/nonlinear properties of a time series by decomposing it into two sub-series: magnitude and sign sub-series (Ashkenazy et al., 2003). The long-range correlation properties of the magnitude and sign sub-series relate to nonlinear and linear behavior of the original time series respectively. We apply this method to the hourly time variability of geoelectrical signals, measured from January 2001 to September 2002 by four stations installed in Basilicata region (southern Italy). Three stations (Giuliano, Marsico and Tito) are located in a seismic area, and one (Laterza) in a low-seismicity area. A site-dependence of the linear/nonlinear properties has been shown, revealing that different dynamics govern signals measured in seismic and low-seismicity areas.
VLF-LF radio signals collected at Bari (South Italy): a preliminary analysis on signal anomalies associated with earthquakes
Authors: Biagi P. F. , Piccolo R. , Castellana L. , Maggipinto T. , Ermini A. , Martellucci S. , Bellecci C. , Perna G. , Capozzi V. , Molchanov O. A. , Hayakawa M. , Ohta K.
Published: April 2010

Abstract. At the beginning of 2002 an OmniPAL receiver was put into operation at the Department of Physics of Bari University (Southern Italy). The electric field strength of five VLF-LF signals transmitted from United Kingdom (f=16kHz), France (f=20.9kHz), Germany (f=23.4kHz), Iceland (f=37.5kHz) and Italy (f=54kHz) has been monitoring with a 5s sampling frequency. In a first step we reduced the amount of the data taking one datum each 10min (mean of the ±5min raw data) and then we smoothed these data by a running adjacent averaging over 7 days. Analysing the trends we obtained, we revealed at first in the signal from the Italian transmitter two clear intensity decreases in April 2002 and in August-September 2002. At these times we observed earthquakes with M=4.3 and M=5.6 respectively near the transmitter-receiver path and a precursory effect in the previous decreases appeared. Then, we noted that all of the five radio trends in the time interval March 2002-February 2003 are more disturbed than in other periods; in particular an evident simultaneous decrease appears in January-February 2003. We propose that these disturbances are related to general excitation of the margin between the African and European plates. In a second step we examined the terminator time (evening) changes for the Italian transmitter in July-September 2002, and we found significant deviations from the mean value at the end of August, which is supportive for some precursory ionospheric signature of earthquakes.
Information entropy analysis of seismicity of Umbria-Marche region (Central Italy)
Authors: Telesca L. , Lapenna V. , Lovallo M.
Published: April 2010

Abstract. We investigated by means of nonlinear tools the temporal distribution of 1983-2003 seismicity of the Umbria-Marche region, Central Italy, that was struck by a strong event (M=5.8) on 26 September 1997. Information entropy analysis has been performed over the full and the aftershock-depleted catalogue. We analysed the series of the interevent times between successive earthquakes and the series of their magnitudes. The time evolution of this measure shows a clear anomalous behaviour in correspondence with the stronger event, more evident in the full catalogue than in the aftershock-depleted one.
Influence of weathering and pre-existing large scale fractures on gravitational slope failure: insights from 3-D physical modelling
Authors: Bachmann D. , Bouissou S. , Chemenda A.
Published: April 2010

Abstract. Using a new 3-D physical modelling technique we investigated the initiation and evolution of large scale landslides in presence of pre-existing large scale fractures and taking into account the slope material weakening due to the alteration/weathering. The modelling technique is based on the specially developed properly scaled analogue materials, as well as on the original vertical accelerator device enabling increases in the "gravity acceleration" up to a factor 50. The weathering primarily affects the uppermost layers through the water circulation. We simulated the effect of this process by making models of two parts. The shallower one represents the zone subject to homogeneous weathering and is made of low strength material of compressive strength σl. The deeper (core) part of the model is stronger and simulates intact rocks. Deformation of such a model subjected to the gravity force occurred only in its upper (low strength) layer. In another set of experiments, low strength (σw) narrow planar zones sub-parallel to the slope surface (σw
Near-seismic effects in ULF fields and seismo-acoustic emission: statistics and explanation
Authors: Molchanov O. , Schekotov A. , Solovieva M. , Fedorov E. , Gladyshev V. , Gordeev E. , Chebrov V. , Saltykov D. , Sinitsin V. I. , Hattori K. , Hayakawa M.
Published: April 2010

Abstract. Preseismic intensification of fracturing has been investigated from occurrence analysis of seismo-acoustic pulses (SA foreshocks) and ULF magnetic pulses (ULF foreshocks) observed in Karimshino station in addition to seismic foreshocks. Such analysis is produced for about 40 rather strong and nearby isolated earthquakes during 2 years of recording. It is found that occurrence rate of SA foreshocks increases in the interval (-12, 0 h) before main shock with 3-times exceeding of background level in the interval (-6, -3 h), and occurrence probability of SA foreshocks (pA~75%) is higher than probability of seismic foreshocks (ps~30%) in the same time interval.ULF foreshocks are masked by regular ULF activity at local morning and daytime, nevertheless we have discovered an essential ULF intensity increase in the interval (-3, +1 h) at the frequency range 0.05-0.3 Hz. Estimated occurrence probability of ULF foreshocks is about 40%. After theoretical consideration we conclude: 1) Taking into account the number rate of SA foreshocks, their amplitude and frequency range, they emit due to opening of fractures with size of L=70-200 m (M=1-2); 2) The electro-kinetic effect is the most promising mechanism of ULF foreshocks, but it is efficient only if two special conditions are fulfilled: a) origin of fractures near fluid-saturated places or liquid reservoirs (aquifers); b) appearance of open porosity or initiation of percolation instability; 3) Both SA and ULF magnetic field pulses are related to near-distant fractures (r<20-30 km); 4) Taking into account number rate and activation period of seismic, SA and ULF foreshocks, it is rather probable that opening of fractures and rupture of fluid reservoirs occur in the large preparation area with horizontal size about 100-200km.
Non double couple seismic sources, faults interaction and hypothesis of self-organized criticality
Authors: Yunga S. , Lutikov A. , Molchanov O.
Published: April 2010

Abstract. Non double couple (NDC) sources are considered in framework of the hypothesis that the process of seismic rupture can be viewed as a result of complicated fault geometry and its segmentation. Analytical approach is found to reveal reliability of NDC measure taking into consideration the values of seismic moment tensor errors. The study focuses on the comparison of the deformation modes of the NDC sources with the stress states in its vicinity. The deformation modes of faulting and fracturing at a small scale in NDC earthquake focus and at regional scale in geological unit were investigated using at the last case summation of seismic moment tensors. These local and regional deformation modes in some of geodynamic regimes confirm the self-similarity assumption. For the whole data set scaling relations seem to be more complicated. This feature implies that besides stresses second order factors, as the hydrothermal or magmatic pore fluids in rock, influence source characteristics and bring new complications in scaling relations.
Measurements of debris flow velocity through cross-correlation of instrumentation data
Authors: Arattano M. , Marchi L.
Published: April 2010

Abstract. Detection of debris flow occurrence can be efficiently obtained through different types of sensors. A pair of ultrasonic sensors placed at a known distance from each other along a torrent have been used as a method to obtain mean front velocity of debris-flows, in addition to their use as detectors of debris flow occurrence. Also seismic and acoustic sensors have been employed to measure debris-flow front velocity and discharge in the same manner. In order to obtain velocity measurements, however, these methods require the presence of a well identifiable and defined main front in the debris flow wave. The time lag between the recordings of the front of the wave at two consecutive stations allows an estimation of its mean velocity. When a well-defined front is not present and no recurrent feature can be found along the wave, the measurement of velocity may prove difficult. The cross-correlation technique may help identifying the mean velocity of the flow in such cases. In fact, cross correlation allows to determine the mean time lag elapsed between the recording of two sets of data of the same event at different positions. This technique may be also used to measure velocity using signals coming from different types of sensors, for instance where a ground vibration detector has been placed along a torrent where an ultrasonic sensor was already present or viceversa. An application has been made using field data recorded through seismic and ultrasonic sensors in a small instrumented catchment in the Italian Alps (Moscardo Torrent).
Acoustic module of the Acquabona (Italy) debris flow monitoring system
Authors: Galgaro A. , Tecca P. R. , Genevois R. , Deganutti A. M.
Published: April 2010

Abstract. Monitoring of debris flows aimed to the assessment of their physical parameters is very important both for theoretical and practical purposes. Peak discharge and total volume of debris flows are crucial for designing effective countermeasures in many populated mountain areas where losses of lives and property damage could be avoided. This study quantifies the relationship between flow depth, acoustic amplitude of debris flow induced ground vibrations and front velocity in the experimental catchment of Acquabona, Eastern Dolomites, Italy. The analysis of data brought about the results described in the following. Debris flow depth and amplitude of the flow-induced ground vibrations show a good positive correlation. Estimation of both mean front velocity and peak discharge can be simply obtained monitoring the ground vibrations, through geophones installed close to the flow channel; the total volume of debris flow can be so directly estimated from the integral of the ground vibrations using a regression line. The application of acoustic technique to debris flow monitoring seems to be of the outmost relevance in risk reduction policies and in the correct management of the territory. Moreover this estimation is possible in other catchments producing debris flows of similar characteristics by means of their acoustic characterisation through quick and simple field tests (Standard Penetration Tests and seismic refraction surveys).
Evaluation of landslide susceptibility of Sete Cidades Volcano (S. Miguel Island, Azores)
Authors: Gomes A. , Gaspar J. L. , Goulart C. , Queiroz G.
Published: April 2010

Abstract. Sete Cidades is an active central volcano with a summit caldera located in the westernmost part of S. Miguel Island (Azores). Since the settlement of the Island, in the 15th century, many landslide events occurred in this volcano, causing extensive damages in buildings and infrastructures. The study of historical records and the observation of new occurrences showed that landslides in the region have been triggered by heavy rainfall periods, earthquakes and erosion. In order to assess landslide susceptibility at Sete Cidades Volcano, landslide scars and associated deposits were mapped through aerial photographs and field surveys. The obtained data were inserted in a GIS to produce a landslide distribution map. It was concluded that the high density landslide areas are related with (1) major scarp faults, (2) the margin of fluvial channels, (3) the sea cliffs and (4) volcanic landforms, namely the caldera wall. About 73% of the mapped events took place in areas where pyroclastic deposits are the dominant lithology and more than 77% occurred where slopes are equal or higher than 20°. These two parameters were integrated and used to generate a preliminary susceptibility map. The incorporation of vulnerability data into the GIS allowed concluding that 30% of dwellings and most of the roads on Sete Cidades Volcano are located in areas where landslide susceptibility is high to very high. Such conclusion should be taken into account for emergency and land use planning.
A preliminary investigation of radar rainfall estimation in the Ardennes region and a first hydrological application for the Ourthe catchment
Authors: Berne A. , ten Heggeler M. , Uijlenhoet R. , Delobbe L. , Dierickx Ph. , de Wit M.
Published: April 2010

Abstract. This paper presents a first assessment of the hydrometeorological potential of a C-band doppler weather radar recently installed by the Royal Meteorological Institute of Belgium near the village of Wideumont in the southern Ardennes region. An analysis of the vertical profile of reflectivity for two contrasting rainfall events confirms the expected differences between stratiform and convective precipitation. The mean areal rainfall over the Ourthe catchment upstream of Tabreux estimated from the Wideumont weather radar using the standard Marshall-Palmer reflectivity-rain rate relation shows biases between +128% and –42% for six selected precipitation events. For two rainfall events the radar-estimated mean areal rainfall is applied to the gauge-calibrated (lumped) HBV-model for the Ourthe upstream of Tabreux, resulting in a significant underestimation with respect to the observed discharge for one event and a closer match for another. A bootstrap analysis using the radar data reveals that the uncertainty in the hourly discharge from the ~1600km2} catchment associated with the sampling uncertainty of the mean areal rainfall estimated from 10 rain gauges evenly spread over the catchment amounts to ±25% for the two events analyzed. This uncertainty is shown to be of the same order of magnitude as that associated with the model variables describing the initial state of the model.