Fractal approaches in investigating the time dynamics of self-potential hourly variability     

Luciano Telesca  Gerardo Colangelo  Vincenzo Lapenna  Maria Macchiato 《International Journal of Earth Sciences》2005,94(2):285-300

Fractal tools have been used to investigate the time dynamics of hourly self-potential data, recorded during the year 2001 by five geoelectrical stations located in one of the most seismic areas of southern Italy. Scaling behaviour has been revealed by means of different statistics: the Lomb Periodogram method, the Detrended Fluctuation Analysis, the Higuchi analysis and the mean distance spanned within the time L. The values of the scaling exponents estimated by means of these methods indicate that the temporal fluctuations of the geoelectrical signals are not typical of purely random stochastic processes (i.e. white noise), but evidence the presence of long-range correlations. Furthermore, it is found that these correlations are linear.  相似文献   

Applications of maximum entropy and optimal number of class interval concepts: Two examples     

Gerardo M. E. Perillo  Eduardo Marone 《Mathematical Geology》1986,18(5):465-476

Two data sets, one from surface sediment samples obtained from a subtidal sand wave and another consisting of three wave-height records representing different oceanographic conditions, are employed to test the application of maximum entropy (ME) and optimal number of class interval (K) concepts. Each data set was modified further to obtain a frequency distribution determined by eight unequal-size class intervals. Both original and modified sets were treated by a reliable statistical method. Comparison of relative entropies and results from statistical treatments show the advantage of the transformation of any original data set by means of ME and K methods before analyzing it further.Contribution 127, Instituto Argentino de Oceanografia.  相似文献   

Determination of optimal numbers of class intervals using maximum entropy     

Gerardo M. E. Perillo  Eduardo Marone 《Mathematical Geology》1986,18(4):401-407

Based on the maximum entropy concept, optimal numbers of class intervals(K) for a closed array of samples has been determined. From the analysis, two values ofK (8 and 19) are selected as the most appropriate. ForK=8, the probability of occurrence on each unequal-size interval isp _i=0.125, whereasK=19 results inp _i=0.0526. An objective method for determining interval limits, modified from a previous method by Full et al. (1984), is also included.Contribution 114, Instituto Argentino de Oceanografia.  相似文献   

Book review     

Hua-Wei Zhou  Louise H. Kellogg  Robert L. Nowack  Gary Mavko  Gerardo G. Tango C.P.G.  Katharine Kadinsky-Cade  Brian J. Mitchell  Louise H. Kellogg  Alexander Berdichevsky  Krzysztof Haman 《Pure and Applied Geophysics》1990,134(1):135-161

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Self-organization maps (SOM) in the definition of a “transfer function” for a diatoms-based climate proxy     

Acevedo-Acosta  Juan David  Martínez-López  Aída  Morales-Acoltzi  Tomás  Albáñez-Lucero  Mirtha  Verdugo-Díaz  Gerardo 《Climate Dynamics》2021,56(1-2):423-437

Climate Dynamics - This study utilizes self-organizing maps (SOM) —a particular type of artificial neural network (ANN) — as a nonlinear analysis tool for identifying species that can...  相似文献   

Calibration and validation of rockfall modelling at regional scale: application along a roadway in Mallorca (Spain) and organization of its management   总被引：1，自引：0，他引：1  

Rosa María Mateos  Inmaculada García-Moreno  Paola Reichenbach  Gerardo Herrera  Roberto Sarro  Joan Rius  Raúl Aguiló  Federica Fiorucci 《Landslides》2016,13(4):751-763

The Tramuntana range, in the northwestern sector of the island of Mallorca (Balearic Islands, Spain), is frequently affected by rockfalls which have caused significant damage, mainly along the road network. In this work, we present the procedure we have applied to calibrate and validate rockfall modelling in this region, using 103 cases of the available detailed rockfall inventory (630 rockfall events collected since the eighteenth century). We have exploited STONE (Guzzetti et al. 2002), a GIS-based rockfall simulation software which computes 2D and 3D rockfall trajectories starting from a DTM and maps of the dynamic rolling friction coefficient and of the normal and tangential energy restitution coefficients. The appropriate identification of these parameters determines the accuracy of the simulation. To calibrate them, we have selected 40 rockfalls along the range which include a wide variety of outcropping lithologies. Coefficients values have been changed in numerous attempts in order to select those where the extent and shape of the simulation matched the field mapping. Best results were summarized with the average statistical values for each parameter and for each geotechnical unit, determining that mode values represent more precisely the data. Initially, for the validation stage, 10 well-known rockfalls exploited in the calibration phase have been selected. Confidence tests have been applied to their modelling results taking into account not only the success but also the mistakes. The best accuracy is obtained when the rockfall has a preferential trajectory and worse results when the rockfall follows two or more trajectories. Additionally, the greater the rockfall runout length, the less precise the simulation is. We have further validated the calibrated parameters along the Ma-road (111 km), the main transportation corridor in the range, using 63 rockfall events that occurred during the past 18 years along the road. Of the rockfalls where source areas were properly identified, 81.5 % are well represented by STONE modelling, as the travel paths and the depositional areas are successfully ascertained. Results of the analysis have been used by the Road Maintenance Service of Mallorca to assess hazard and risk posed by rockfall at regional scale to design the road management plan.  相似文献   

Spatio-temporal variations of seismicity in the southern Peru and northern Chile seismic gaps     

Diana Comte  Gerardo Suárez 《Pure and Applied Geophysics》1993,140(2):317-330

The spatio-temporal variation of seismicity in the southern Peru and northern Chile seismic gaps is analyzed with teleseismic data (m _b 5.5) between 1965 and 1991, to investigate whether these gaps present the precursory combination of compressional outer-rise and tensional downdip events observed in other subduction zones. In the outer-rise and the inner-trench (0 to 100 km distance from the trench) region, lower magnitude (5.0m _b <5.5) events were also studied. The results obtained show that the gaps in southern Peru and northern Chile do not present compressional outer-rise events. However, both gaps show a continuous, tensional downdip seismicity. For both regions, the change from compressional to tensional regime along the slab occurs at a distance of about 160 km from the trench, apparently associated with the coupled-uncoupled transition of the interplate contact zone. In southern Peru, an increase of compressional seismicity near the interplate zone and of tensional events (5.0m _b 6.3) in the outer-rise and inner-trench regions is observed between 1987 and 1991. A similar distribution of seismicity in the outer-rise and inner-trench regions is observed with earthquakes (m _b <5.5). In northern Chile there is a relative absence of compressional activity (m _b 5.5) near the interplate contact since the sequence of December 21, 1967. After that, only a cluster of low-magnitude compressional events has been located in the area 50 to 100 km from the trench. The compressional activity occurring near the interplate zone in both seismic gaps represents that a seismic preslip is occurring in and near the plate contact. Therefore, if this seismic preslip is associated with the maturity of the gap, the fact that it is larger in southern Peru than in northern Chile may reflect that the former gap is more mature than the latter. However, the more intense downdip tensional activity and the absence of compressional seismicity near the contact zone observed in northern Chile, may also be interpreted as evidence that northern Chile is seismically more mature than southern Peru. Therefore, the observed differences in the distribution of stresses and seismicity analyzed under simple models of stress accumulation and transfer in coupled subduction zones are not sufficient to assess the degree of maturity of a seismic gap.  相似文献   

HYDRAULIC ANALYSES FOR A NEW BRIDGE OVER THE PARANA RIVER, ARGENTINA     

Andrés RODRIGUEZ  Daniel Farías  Héctor R.BRAVO  Edgar Castelló 《国际泥沙研究》2003,18(2)

1 INTRODUCTION The Parana River in South America ranks as the sixth largest in the world in terms of average discharge (22 x 103 m3/s according to Schumm and Winkley, 1994), and its Argentinean reach stretches from Puerto Iguazu on the north to the Rio de la Plata estuary in the south (Fig. 1). Its estimated average suspended load, bed load, and total load are 23 x 106, 2.2 x 106, and 25.2 x 106 metric tons per year, respectively (Paoli and Schreider, 2001.) The economic developmen…  相似文献   

Reduced-dynamic and kinematic baseline determination for the Swarm mission     

Allende-Alba  Gerardo  Montenbruck  Oliver  Jäggi  Adrian  Arnold  Daniel  Zangerl  Franz 《GPS Solutions》2017,21(3):1275-1284

GPS Solutions - The Swarm mission of the European Space Agency was launched in November 2013 with the objective of performing measurements of the earth’s magnetic field with unprecedented...  相似文献   

Landslide databases in the Geological Surveys of Europe     

Gerardo Herrera  Rosa María Mateos  Juan Carlos García-Davalillo  Gilles Grandjean  Eleftheria Poyiadji  Raluca Maftei  Tatiana-Constantina Filipciuc  Mateja Jemec Auflič  Jernej Jež  Laszlo Podolszki  Alessandro Trigila  Carla Iadanza  Hugo Raetzo  Arben Kociu  Maria Przyłucka  Marcin Kułak  Michael Sheehy  Xavier M. Pellicer  Charise McKeown  Graham Ryan  Veronika Kopačková  Michaela Frei  Dirk Kuhn  Reginald L. Hermanns  Niki Koulermou  Colby A. Smith  Mats Engdahl  Pere Buxó  Marta Gonzalez  Claire Dashwood  Helen Reeves  Francesca Cigna  Pavel Liščák  Peter Pauditš  Vidas Mikulėnas  Vedad Demir  Margus Raha  Lídia Quental  Cvjetko Sandić  Balazs Fusi  Odd Are Jensen 《Landslides》2018,15(2):359-379

Landslides are one of the most widespread geohazards in Europe, producing significant social and economic impacts. Rapid population growth in urban areas throughout many countries in Europe and extreme climatic scenarios can considerably increase landslide risk in the near future. Variability exists between European countries in both the statutory treatment of landslide risk and the use of official assessment guidelines. This suggests that a European Landslides Directive that provides a common legal framework for dealing with landslides is necessary. With this long-term goal in mind, this work analyzes the landslide databases from the Geological Surveys of Europe focusing on their interoperability and completeness. The same landslide classification could be used for the 849,543 landslide records from the Geological Surveys, from which 36% are slides, 10% are falls, 20% are flows, 11% are complex slides, and 24% either remain unclassified or correspond to another typology. Most of them are mapped with the same symbol at a scale of 1:25,000 or greater, providing the necessary information to elaborate European-scale susceptibility maps for each landslide type. A landslide density map was produced for the available records from the Geological Surveys (LANDEN map) showing, for the first time, 210,544 km² landslide-prone areas and 23,681 administrative areas where the Geological Surveys from Europe have recorded landslides. The comparison of this map with the European landslide susceptibility map (ELSUS 1000 v1) is successful for most of the territory (69.7%) showing certain variability between countries. This comparison also permitted the identification of 0.98 Mkm² (28.9%) of landslide-susceptible areas without records from the Geological Surveys, which have been used to evaluate the landslide database completeness. The estimated completeness of the landslide databases (LDBs) from the Geological Surveys is 17%, varying between 1 and 55%. This variability is due to the different landslide strategies adopted by each country. In some of them, landslide mapping is systematic; others only record damaging landslides, whereas in others, landslide maps are only available for certain regions or local areas. Moreover, in most of the countries, LDBs from the Geological Surveys co-exist with others owned by a variety of public institutions producing LDBs at variable scales and formats. Hence, a greater coordination effort should be made by all the institutions working in landslide mapping to increase data integration and harmonization.  相似文献