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  • 04.04. Geology  (10)
  • JSTOR Archive Collection Business II  (7)
  • 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring
  • 04. Solid Earth::04.06. Seismology::04.06.09. Waves and wave analysis
  • Wiley  (11)
  • Elsevier B.V.  (9)
  • M. E. Sharpe
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  • 1
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    Supervised learning (2021)
    Elsevier B.V.
    Details
    Publication Date: 2021-02-01
    Description: In supervised classification, we search criteria allowing us to decide whether a sample belongs to a certain class of patterns. The identification of such decision functions is based on examples where we know a priori to which class they belong. The distinction of seismic signals, produced from earthquakes and nuclear explosions, is a classical problem of discrimination using classification with supervision. We move on from observed data—signals originating from known earthquakes and nuclear tests—and search for criteria on how to assign a class to a signal of unknown origin. We begin with Principal Component Analysis (PCA) and Fisher's Linear Discriminant Analysis (FLDA), identifying a linear element separating groups at best. PCA, FLDA, and likelihood-based approaches make use of statistical properties of the groups. Considering only the number of misclassified samples as a cost, we may prefer alternatives, such as the Multilayer Perceptrons (MLPs). The Support Vector Machines (SVMs) use a modified cost function, combining the criterion of the minimum number of misclassified samples with a request of separating the hulls of the groups with a margin as wide as possible. Both SVMs and MLPs overcome the limits of linear discrimination. A famous example for the advantages of the two techniques is the eXclusive OR (XOR) problem, where we wish to form classes of objects having the same parity—even, e.g., (0,0), (1,1) or odd, e.g., (0,1), (1,0). MLPs and SVMs offer effective methods for the identification of nonlinear decision functions, allowing us to resolve classification problems of any complexity provided the data set used during earning is sufficiently large. In Hidden Markov Models (HMMs), we consider observations where their meaning depends on their context. Observations form a causal chain generated by a hidden process. In Bayesian Networks (BNs) we represent conditional (in)dependencies between a set of random variables by a graphical model. In both HMMs and BNs, we aim at identifying models and parameters that explain observations with a highest possible degree of probability.
    Description: Published
    Description: 33-85
    Description: 5T. Sismologia, geofisica e geologia per l'ingegneria sismica
    Keywords: pattern recognition ; supervised learning ; Support Vector Machines ; Multilayer Perceptrons ; Hidden Markov Models ; Bayesian Networks ; 04.04. Geology ; 04.06. Seismology ; 04.07. Tectonophysics ; 04.08. Volcanology ; 05.04. Instrumentation and techniques of general interest
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: book chapter
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  • 2
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    Patterns, objects, and features (2021)
    Elsevier B.V.
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    Publication Date: 2021-02-01
    Description: Patterns and objects are described by a variety of characteristics, namely features and feature vectors. Features can be numerical, ordinal, and categorical. Patterns can be made up of a number of objects, such as in speech processing. In geophysics, numerical features are the most common ones and we focus on those. The choice of appropriate features requires a priori reasoning about the physical relation between patterns and features. We present strategies for feature identification and procedures suitable for pattern recognition. In time series analysis and image processing, the direct use of raw data is not feasible. Procedures of feature extraction, based on locally encountered characteristics of the data, are applied. Here we present the problem of delineating segments of interest in time series and textures in image processing. In transformations, we “translate” our raw data to a form suitable for learning. In Principal Component Analysis, we rotate the original features to a system of uncorrelated variables, limiting redundancy. Independent Component Analysis follows a similar strategy, transforming our data into variables independent of each other. Fourier transform and wavelet transform are based on the representation of the original data as a series of basis functions—sines and cosines or finite-length wavelets. Redundancy reduction is achieved considering the contributions of the single basis functions. Even though a large number of features help to solve a classification problem, feature vectors with high dimensions pose severe problems. Besides the computational burden, we encounter problems known under the term “curse of dimensionality.” The curse of dimensionality entails the necessity of feature selection and reduction, which includes a priori considerations as well as redundancy reduction. The significance of features may be evaluated with tests, such as Student’s t or Hotelling's T2, and, in more complex problems, with cross-validation methods.
    Description: Published
    Description: 3-13
    Description: 5T. Sismologia, geofisica e geologia per l'ingegneria sismica
    Keywords: pattern recognition ; objects ; features ; 04.04. Geology ; 04.06. Seismology ; 04.07. Tectonophysics ; 04.08. Volcanology ; 05.04. Instrumentation and techniques of general interest
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 3
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    A posteriori analyses—advantages and pitfalls of pattern recognition techniques (2021)
    Elsevier B.V.
    Details
    Publication Date: 2021-02-01
    Description: In this chapter, we deal with a posterior analysis of supervised and unsupervised learning techniques. Concerning supervised learning, we discuss methods of cross-validation and assessment of uncertainty of tests by means of the “Receiver Operation Curve” and the “Kappa-Statistics.” We show the importance of appropriate target information. Furthermore, features are critical; when they are not properly chosen, they fail to describe objects in a unique way. A critical attitude is mandatory to validate the success of an application. A high score of success does not automatically mean that a method is truly effective. At the same time, users should not despair when the desired success is not achieved. A posteriori analysis on the reasons for an apparent failure may provide useful insights into the problem. Targets may not be appropriately defined, features can be inadequate, etc. Problems can be often fixed by adjusting a few choices; sometimes a change of strategy may be necessary to improve results. In unsupervised learning, we ask whether the structures revealed in the data are meaningful. Cluster analysis offers rules giving formal answers to this question; however, such rules are not generally applicable. In some cases, a heuristic approach may be necessary.
    Description: Published
    Description: 237-259
    Description: 5T. Sismologia, geofisica e geologia per l'ingegneria sismica
    Keywords: pattern recognition ; a posteriori analysis ; supervised learning ; unsupervised learning ; cross validation ; assessment of uncertainty ; Receiver Operation Curve ; Kappa-Statistics ; 04.04. Geology ; 04.06. Seismology ; 04.07. Tectonophysics ; 04.08. Volcanology ; 05.04. Instrumentation and techniques of general interest
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 4
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    Unsupervised learning (2021)
    Elsevier B.V.
    Details
    Publication Date: 2021-02-01
    Description: Unsupervised learning is based on the definition of an appropriate metrics defining the similarity of patterns. On the basis of the metrics, we form groups or clusters of patterns following various strategies. In partitioning cluster analysis, we form disjoint clusters. Being faced with data, where clusters still exhibit heterogeneities or subclusters, we may adopt the strategy of hierarchical clustering, which leads to the generation of the so-called dendrograms. In the partitioning strategy, we choose a priori the number of clusters we wish to form, whereas in the hierarchical strategy, the number of clusters depends on the resolution we want to have. Density-based clustering considers local structures of a data set. We consider a unit volume in our data space and derive the density of samples within this volume. Moving toward neighboring volumes, we verify whether the number of samples has dropped below a threshold. If this is the case, we identify a heterogeneity, otherwise we join the neighboring volumes to a common cluster. Self-Organizing Maps (SOMs) provide a way of representing multidimensional data in much lower dimensional spaces than the original data set. The process of reducing the dimensionality of vectors is essentially a data compression technique known as vector quantization. The SOM technique creates a network that stores information in a way that it maintains the topological relationships within the patterns of the data set. Each node of the network represents a number of patterns. Assigning a color code to the nodes, the representation of pattern characteristics with high-dimensional feature vectors becomes extremely effective.
    Description: Published
    Description: 87-124
    Description: 5T. Sismologia, geofisica e geologia per l'ingegneria sismica
    Keywords: pattern recognition ; unsupervised learning ; cluster analysis ; Density-based clustering ; Self-Organizing Maps ; 04.04. Geology ; 04.06. Seismology ; 04.07. Tectonophysics ; 04.08. Volcanology ; 05.04. Instrumentation and techniques of general interest
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: book chapter
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  • 5
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    Applications with unsupervised learning (2021)
    Elsevier B.V.
    Details
    Publication Date: 2021-02-01
    Description: This chapter demonstrates how Unsupervised Learning can be applied in Geophysics. It starts with an example of clustering seismic spectra obtained on Stromboli volcano. K-means clustering as well as clustering using the Adaptive Criterion are applied. The latter criterion is preferred as it better matches the statistical characteristics of the data. Clusters show close relation to the state of volcanic activity. Density based clustering reveals groups whose hulls can be of irregular shape. This makes the method attractive, among others, for the identification of structural elements in geology, which often do not have a simple geometry. An example application is discussed considering the distribution of earthquake locations on Mt Etna, which clearly evidence structures already identified by other, independent evidences. Using SOM we aim at data reduction and effective graphical visualization. In an example for climate data we demonstrate the application of SOM for zoning purposes. Besides, the temporal evolution of spectral seismic data recorded on Mt Etna can be effectively monitored using SOM. We further illustrate the use of SOM for directional data, which can be handled best using a toroidal sheet geometry. We discuss this using a data set of seismic moment tensors of Mediterranean earthquakes.
    Description: Published
    Description: 189-234
    Description: 5T. Sismologia, geofisica e geologia per l'ingegneria sismica
    Keywords: pattern recognition ; unsupervised learning ; Density based clustering ; Stromboli ; earthquakes ; volcanic activity ; structural data ; seismic moment tensors ; 04.04. Geology ; 04.06. Seismology ; 04.07. Tectonophysics ; 04.08. Volcanology ; 05.04. Instrumentation and techniques of general interest
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 6
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    Software manuals (2021)
    Elsevier B.V.
    Details
    Publication Date: 2021-02-01
    Description: In this chapter, we present scripts and programs that accompany this book. Five MATLAB scripts regard simple examples related to supervised learning, that is, linear discrimination, the perceptron, support vector machines, and hidden Markov models. Seven scripts are devoted to unsupervised learning, such as K-means and fuzzy clustering, agglomerative clustering, density-based clustering, and clustering of patterns where features are correlated. These scripts provide a starting point for the reader, who can adjust and modify the codes with respect to proper needs. Besides, we provide sources and executables of programs that can be readily applied to larger and more complex datasets. These programs regard supervised learning using multilayerperceptron and support vector machines. KKAnalysis is a toolbox for unsupervised learning and offers various options of clustering and the use of self-organizing maps. The programs offer graphical user interfaces (GUI) to facilitate their use and create both graphical and alphanumeric output that can be used in further processing steps. The programs come along with real-world datasets that are also discussed in the example applications presented in various chapters of the book. Other propaedeutic material can be found in a folder called “miscellaneous.”
    Description: Published
    Description: 261-313
    Description: 5T. Sismologia, geofisica e geologia per l'ingegneria sismica
    Keywords: pattern recognition ; software manuals ; MATLAB scripts ; 04.04. Geology ; 04.06. Seismology ; 04.07. Tectonophysics ; 04.08. Volcanology ; 05.04. Instrumentation and techniques of general interest
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 7
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    Applications of supervised learning (2021)
    Elsevier B.V.
    Details
    Publication Date: 2021-02-15
    Description: This chapter presents applications of supervised learning in various geophysical disciplines, being them seismology, geodesy, magnetism, and others. For all examples, we provide a brief introduction to the geophysical background. Practical aspects, such as normalization issues and feature selection, are discussed. A posteriori considerations shed light on the geophysical problem, such as the importance of model parameters in regression, the possible nonuniqueness in inversion, and flaws in the definition of targets. We demonstrate multilayer perceptrons (MLPs) as classifiers of seismic waveforms. Besides, we show how the use of MLP is straightforward in the context of inversion of various kinds of data, for example, seismic, geodetic, and magnetic. Regression with MLP is applied to magnetotelluric and seismic data. Multiclass classification with support vector machine (SVM) is discussed for infrasound waveforms and volcanic rocks using geochemical characteristics. We introduce the use of SVM in the context of regression, which is formally less immediate than for MLP, but yields good results. An example deals with empirical ground motion estimation during earthquakes. In hidden Markov models and Bayesian networks one considers the interrelation between observations rather than single patterns. We show their benefits in various applications, from seismic waveform classification aimed at the forecast of volcanic unrest up to their use in tsunami early-warning systems.
    Description: Published
    Description: 127-187
    Description: 5T. Sismologia, geofisica e geologia per l'ingegneria sismica
    Keywords: pattern recognition ; supervised learning ; multilayer perceptrons ; seismic data ; magnetotelluric data ; infrasound waveforms ; volcanic rocks ; geochemical characteristics ; 04.04. Geology ; 04.06. Seismology ; 04.07. Tectonophysics ; 04.08. Volcanology ; 05.04. Instrumentation and techniques of general interest
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 8
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    Integrated on‐land‐offshore stratigraphy of the Campi Flegrei caldera: new insights into the volcano‐tectonic evolution in the last 15 kyr (2021)
    Wiley
    Details
    Publication Date: 2022-06-22
    Description: Silicic calderas are volcanic systems whose unrest evolution is more unpredictable than other volcano types because they often do not culminate in an eruption. Their complex structure strongly influences the post-collapse volcano-tectonic evolution, usually coupling volcanism and ground deformation. Among such volcanoes, the Campi Flegrei caldera (southern Italy) is one of the most studied. Significant long- and short-term ground deformations characterize this restless volcano. Several studies performed on the marinecontinental succession exposed in the central sector of the Campi Flegrei caldera provided a reconstruction of ground deformation during the last 15 kyr. However, considering that over one-third of the caldera is presently submerged beneath the Pozzuoli Gulf, a comprehensive stratigraphic on-land-offshore framework is still lacking. This study aims at reconstructing the offshore succession through analysis of high-resolution single and multichannel reflection seismic profiles and correlates the resulting seismic stratigraphic framework with the stratigraphy reconstructed on-land. Results provide new clues on the causative relations between the intra-caldera marine and volcaniclastic sedimentation and the alternating phases of marine transgressions and regressions originated by the interplay between ground deformation and sea-level rise. The volcano-tectonic reconstruction, provided in this work, connects the major caldera floor movements to the large Plinian eruptions of Pomici Principali (12 ka) and Agnano Monte Spina (4.55 ka), with the onset of the first post-caldera doming at ~10.5 ka. We emphasize that ground deformation is usually coupled with volcanic activity, which shows a self-similar pattern, regardless of its scale. Thus, characterizing the long-term deformation history becomes of particular interest and relevance for hazard assessment and definition of future unrest scenarios.
    Description: Published
    Description: 855-882
    Description: 1V. Storia eruttiva
    Description: JCR Journal
    Keywords: offshore stratigraphy ; seismic units ; La Starza succession ; volcanism, ; 04.08. Volcanology ; 04.04. Geology ; 04.07. Tectonophysics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 9
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    Active Extension in a Foreland Trapped Between Two Contractional Chains: The South Apulia Fault System (SAFS) (2020)
    Wiley
    Details
    Publication Date: 2020-07-08
    Description: The response of continental forelands to subduction and collision is a widely investigated topic in geodynamics. The deformation occurring within a foreland shared by two opposite‐verging chains, however, is uncommon and poorly understood. The Apulia Swell in the southern end of the Adria microplate (Africa‐Europe plate boundary, central Mediterranean Sea) represents one of these cases, as it is the common foreland of the SW verging Albanides‐Hellenides and the NE verging Southern Apennines merging into the SSE verging Calabrian Arc. We investigated the internal deformation of the Apulia Swell using multiscale geophysical data: multichannel seismic profiles recording up to 12‐s two‐way time (TWT) for a consistent image of the upper crust; high‐resolution multichannel seismic profiles, high‐resolution multibeam bathymetry, and CHIRP profiles acquired by R/V OGS Explora to constrain the Quaternary geological record. The results of our analyses characterize the geometry of the South Apulia Fault System (SAFS), a 100‐km‐long and 12‐km‐wide structure attesting an extensional (and possibly transtensional) response of the foreland to the two contractional fronts. The SAFS consists of two NW‐SE right‐stepping master faults and several secondary structures. The SAFS activity spans from the Early Pleistocene through the Holocene, as testified by the bathymetric and high‐resolution seismic data, with long‐term slip rates in the range of 0.2–0.4 mm/yr. Considering the position within an area with few or none other active faults in the surroundings, the dimension, and the activity rates, the SAFS can be a candidate causative fault of the 20 February 1743, M 6.7, earthquake.
    Description: Italian Ministry for Education, University, and Research (MIUR), Premiale 2014 D. M. 291 03/05/2016.
    Description: Published
    Description: e2020TC006116
    Description: 2T. Deformazione crostale attiva
    Description: 2TR. Ricostruzione e modellazione della struttura crostale
    Description: JCR Journal
    Keywords: active tectonics ; apulia ; south apulia fault system ; 1743 earthquake ; marine geology ; stable continental region ; ionian sea ; active faults ; subsurface geology ; seismic interpretation ; 04.04. Geology ; 04.07. Tectonophysics ; 04.02. Exploration geophysics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 10
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    New coring study in Augusta Bay expands understanding of offshore tsunami deposits (Eastern Sicily, Italy) (2019)
    Wiley
    Details
    Publication Date: 2021-01-25
    Description: Tsunami deposits present an important archive for understanding tsunami histories and dynamics. Most research in this field has focused on onshore preserved remains, while the offshore deposits have received less attention. In 2009, during a coring campaign with theItalian Navy Magnaghi, four 1 m long gravity cores (MG cores) were sampled from the northern part of Augusta Bay, along a transect in 60 to 110 m water depth. These cores were taken in the same area where a core (MS06) was collected in 2007 about 2.3 km offshore Augusta at a water depth of 72 m below sea level. Core MS06 consisted of a 6.7 m long sequence that included 12 anomalous intervals interpreted as the primary effect of tsunami backwash waves in the last 4500 years. In this study, tsunami deposits were identified, based on sedimentology and displaced benthic foraminifera (as for core MS06) reinforced by X-ray fluorescence data. Two erosional surfaces (L1 and L2) were recognized coupled with grain size increase, abundant Posidonia oceanica seagrass remains and a significant amount of Nubecularia lucifuga, an epiphytic sessile benthic foraminifera considered to be transported from the inner shelf. The occurrence of Ti/Ca and Ti/Sr increments, coinciding with peaks in organic matter (Mo inc/coh) suggests terrestrial run-off coupled with an input of organic matter. The L1 and L2 horizons were attributed to two distinct historical tsunamis (AD 1542 and AD 1693) by indirect age-estimation methods using 210Pb profiles and the comparison of Volume Magnetic Susceptibility data between MG cores and MS06 cores. One most recent bioturbated horizon (Bh), despite not matching the above listed interpretative features, recorded an important palaeoenvironmental change that may correspond to the AD 1908 tsunami. These findings reinforce the value of offshore sediment records as an underutilized resource for the identification of past tsunamis.
    Description: Published
    Description: 1553-1576
    Description: 6T. Studi di pericolosità sismica e da maremoto
    Description: JCR Journal
    Keywords: Eastern Sicily ; tsunami ; foraminifera ; sedimentology ; XRF core scanning ; 04.04. Geology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 11
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    Time reverse location of seismic long-period events recorded on Mt Etna (2012)
    Wiley
    Details
    Publication Date: 2017-04-04
    Description: We present the first application of a time reverse location method in a volcanic setting, for a family of long-period (LP) events recorded on Mt Etna. Results are compared with locations determined using a full moment tensor grid search inversion and cross-correlation method. From 2008 June 18 to July 3, 50 broad-band seismic stations were deployed on Mt Etna, Italy, in close proximity to the summit. Two families of LP events were detected with dominant spectral peaks around 0.9 Hz. The large number of stations close to the summit allowed us to locate all events in both families using a time reversal location method. The method involves taking the seismic signal, reversing it in time, and using it as a seismic source in a numerical seismic wave simulator where the reversed signals propagate through the numerical model, interfere constructively and destructively, and focus on the original source location. The source location is the computational cell with the largest displacement magnitude at the time of maximum energy current density inside the grid. Before we located the two LP families we first applied the method to two synthetic data sets and found a good fit between the time reverse location and true synthetic location for a known velocity model. The time reverse location results of the two families show a shallow seismic region close to the summit in agreement with the locations using a moment tensor full waveform inversion method and a cross-correlation location method.
    Description: Published
    Description: 452-462
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: Volcano seismology ; Computational seismology ; Wave propagation ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.06. Seismology::04.06.09. Waves and wave analysis
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  • 12
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    Narrow-band, transient signals in Central Apennines, Italy: hints for underground fluid migration? (2012)
    Wiley
    Details
    Publication Date: 2017-04-04
    Description: In this paper we investigate nature and properties of narrow-band, transient seismic signals observed by a temporary array deployed in the Val Tiberina area (central Apennines, Italy). These signals are characterized by spindle-shaped, harmonic waveforms with no clear S-wave arrivals. The first portion of the seismograms exhibits a main frequency peak centred at 4.5 Hz, while the spectrum of the slowly decaying coda is peaked at about 2 Hz. Events discrimination is performed using a matched-filtering technique, resulting in a set of 2466 detections spanning the 2010 January–March time interval. From a plane-wave-fitting procedure, we estimate the kinematic properties of signals pertaining to a cluster of similar events. The repetition of measurements over a large number of precisely aligned seismograms allows for obtaining a robust statistics of horizontal slownesses and propagation azimuths associated with the early portion of the waveforms. The P-wave arrival exhibits horizontal slownesses around 0.1 s km−1, thus suggesting waves impinging at the array almost vertically. Separately, we use traveltimes measured at a sparse network to derive independent constraints on epicentral location. Ray parameters and azimuths are calibrated using slowness measurements from a local, well-located earthquake. After this correction, the joint solution from traveltime inversion and array analysis indicates a source region spanning the 1–3 km depth interval. Considerations related to the source depth and energy, and the occurrence rate which is not related to the daily and weekly working cycles, play against a surface, artificial source. Instead, the close resemblance of these signals to those commonly observed in volcanic environments suggest a source mechanism related to the resonance of a fluid–filled fracture, likely associated with instabilities in the flux of pressurized CO2.
    Description: Published
    Description: 918-928
    Description: 1.1. TTC - Monitoraggio sismico del territorio nazionale
    Description: JCR Journal
    Description: reserved
    Keywords: Fracture and flow ; Earthquake source observations ; Interface waves ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring
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  • 13
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    Depth-dependent intrinsic and scattering seismic attenuation in north central Italy (2011)
    Wiley
    Details
    Publication Date: 2017-04-04
    Description: In this study the attenuation mechanism of seismic wave energy in north central Italy is estimated using low-magnitude earthquake local data recorded at six stations managed by INGV. Most of the analysed events are located along the Alpine chain in the zone of Iseo and Garda lakes, while a minor part in the Po valley. The zone investigated is characterized by the occurrence of significantly intense earthquakes (magnitude up to 6.6) the most recent occurred in 2004 close to the city of Sal`o on the coast of the Garda lake (Mw = 5.0). Due to the high population density and presence of industrial activity the investigated area is characterized by a high seismic risk. First, the ordinary Multiple Lapse Time Window Analysis (MLTWA) method is applied in the assumption of uniformvelocity and scattering and the couple of B0, the seismic albedo and Le−1, the extinction length inverse (corresponding to the total attenuation coefficient) is calculated in the frequency bands of 1.5, 3, 6 and 12 Hz. To retrieve more realistic estimates, the obtained values of B0 and Le−1 are corrected taking into account the effects of a depth-dependent earth model, consisting of an earth structure characterized by a transparent upper mantle and a heterogeneous crust. We find that the corrected intrinsic and scattering attenuation parameters (which are proportional to the inverse of the intrinsic/scattering quality factors, QI−1 and Qs−1) are strongly frequency dependent, with a prevalence of scattering attenuation over the intrinsic dissipation. The corrected and uncorrected values of total Q are in agreement with the total Q values obtained with different approaches for the same area.
    Description: Published
    Description: 3.1. Fisica dei terremoti
    Description: JCR Journal
    Description: reserved
    Keywords: Seismic Attenuation ; Coda Waves ; Wave Scattering and Diffraction ; 04. Solid Earth::04.06. Seismology::04.06.09. Waves and wave analysis
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 14
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    Time reverse location of seismic long-period events recorded on Mt Etna (2011)
    Wiley
    Details
    Publication Date: 2017-04-04
    Description: We present the first application of a time reverse location method in a volcanic setting, for a family of long-period (LP) events recorded on Mt Etna. Results are compared with locations determined using a full moment tensor grid search inversion and cross-correlation method. From 2008 June 18 to July 3, 50 broad-band seismic stations were deployed on Mt Etna, Italy, in close proximity to the summit. Two families of LP events were detected with dominant spectral peaks around 0.9 Hz. The large number of stations close to the summit allowed us to locate all events in both families using a time reversal location method. The method involves taking the seismic signal, reversing it in time, and using it as a seismic source in a numerical seismic wave simulator where the reversed signals propagate through the numerical model, interfere constructively and destructively, and focus on the original source location. The source location is the computational cell with the largest displacement magnitude at the time of maximum energy current density inside the grid. Before we located the two LP families we first applied the method to two synthetic data sets and found a good fit between the time reverse location and true synthetic location for a known velocity model. The time reverse location results of the two families show a shallow seismic region close to the summit in agreement with the locations using a moment tensor full waveform inversion method and a cross-correlation location method.
    Description: In press
    Description: (11)
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: Volcano seismology ; Computational seismology ; Wave propagation ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.06. Seismology::04.06.09. Waves and wave analysis
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  • 15
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    Tsunami early warning using earthquake rupture duration and P-wave dominant-period: the importance of length and depth of faulting (2011)
    Wiley
    Details
    Publication Date: 2017-04-03
    Description: After an earthquake, rapid, real-time assessment of hazards such as ground shaking and tsunami potential is important for early warning and emergency response. Tsunami potential depends on sea floor displacement, which is related to the length, L, width, W, mean slip, D, and depth, z, of earthquake rupture. Currently, the primary discriminant for tsunami potential is the centroid-moment tensor magnitude, MwCMT, representing the seismic potency LWD, and estimated through an indirect, inversion procedure. The obtained MwCMT and the implied LWD value vary with the depth of faulting, assumed earth model and other factors, and is only available 30 min or more after an earthquake. The use of more direct procedures for hazard assessment, when available, could avoid these problems and aid in effective early warning. Here we present a direct procedure for rapid assessment of earthquake tsunami potential using two, simple measures on P-wave seismograms – the dominant period on the velocity records, Td, and the likelihood that the high-frequency, apparent rupture-duration, T0, exceeds 50-55 sec. T0 can be related to the critical parameters L and z, while Td may be related to W, D or z. For a set of recent, large earthquakes, we show that the period-duration product TdT0 gives more information on tsunami impact and size than MwCMT and other currently used discriminants. All discriminants have difficulty in assessing the tsunami potential for oceanic strike-slip and back-arc or upper-plate, intraplate earthquake types. Our analysis and results suggest that tsunami potential is not directly related to the potency LWD from the “seismic” faulting model, as is assumed with the use of the MwCMT discriminant. Instead, knowledge of rupture length, L, and depth, z, alone can constrain well the tsunami potential of an earthquake, with explicit determination of fault width, W, and slip, D, being of secondary importance. With available real-time seismogram data, rapid calculation of the direct, period- duration discriminant can be completed within 6-10 min after an earthquake occurs and thus can aid in effective and reliable tsunami early warning.
    Description: In press
    Description: 1.1. TTC - Monitoraggio sismico del territorio nazionale
    Description: JCR Journal
    Description: open
    Keywords: Earthquake dynamics ; Earthquake source observations ; Seismic monitoring ; Body waves ; Early warning ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 16
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    Recent seismicity and crustal stress field in the Lucanian Apennines and surrounding areas (Southern Italy): Seismotectonic implications (2009)
    Elsevier B.V.
    Details
    Publication Date: 2017-04-04
    Description: We analyzed the instrumental seismicity of Southern Italy in the area including the Lucanian Apennines and Bradano foredeep, making use of the most recent seismological data base available so far. P- and S-wave arrival times, recorded by the Italian National Seismic Network (RSNC) operated by the Istituto Nazionale di Geofisica e Vulcanologia (INGV), were re-picked along with those of the SAPTEX temporary array deployed in the region in the period 2001–2004. For some events located in the upper Val d'Agri, we also used data from the Eni-Agip oil company seismic network. We examined the seismicity occurred during the period between 2001 and 2006, considering 514 events with magnitudes M≥2.0. We computed the VP/VS ratio obtaining a value of 1.83 and we carried out an analysis for the one-dimensional (1D) velocity model that approximates the seismic structure of the study area. Earthquakes were relocated and, for well- recorded events, we also computed 108 fault plane solutions. Finally, using 58 solutions, the most constrained, we computed regional stress field in the study area. Earthquake distribution shows three main seismic regions: the westernmost (Lucanian Apennines) characterized by high background seismicity, mostly with shallow hypocenters, the easternmost below the Bradano foredeep and the Murge with deeper and more scattered seismicity, and finally the more isolated and sparse seismicity localized in the Sila Range and in the offshore area along the northeastern Calabrian coast. Focal mechanisms computed in this work are in large part normal and strike-slip solutions and their tensional axes (T-axes) have a generalized NE–SW orientation. The denser station coverage allowed us to improve hypocenters determination compared to those obtained by using only RSNC data, for a better characterization of the crustal and subcrustal seismicity in the study area.
    Description: Published
    Description: 130-144
    Description: 3.2. Tettonica attiva
    Description: 5.7. Consulenze in favore di istituzioni nazionali e attività nell'ambito di trattati internazionali
    Description: JCR Journal
    Description: reserved
    Keywords: Lucanian Apennines ; Southern Italy ; Seismicity ; 1D velocity model ; Focal mechanisms ; Stress field ; 04. Solid Earth::04.06. Seismology::04.06.01. Earthquake faults: properties and evolution ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 17
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    Mantle wedge anisotropy in Southern Tyrrhenian Subduction Zone (Italy), from receiver function analysis (2008)
    Elsevier B.V.
    Details
    Publication Date: 2017-04-04
    Description: We constrain mantle wedge seismic structure in the Southern Tyrrhenian Subduction Zone (Italy) using teleseismic receiver functions (RF) recorded at station CUC of the Mednet seismographic network. Station CUC lies above the northern portion of the Calabrian slab segment, which is recognized from deep seismicity and tomographic imaging as a narrow, laterally high-arched slab fragment, extending from the surface below Calabria down to the transition zone. To better define the descending slab interface and possible shear-coupled flow in the mantle wedge above the slab, we computed receiver functions from the P-coda of 147 teleseismic events to analyze the back-azimuth dependence of Ps converted phases from interfaces beneath CUC. We stack the RF data-set with back azimuth to compute its harmonic expansion, which relates to the effects of interface dip and anisotropy at layer boundaries. The seismic structure constrained through the RF analysis is characterized in its upper part by a sub-horizontal Moho at about 25 km depth, overlying a thin isotropic layer at top of mantle. For the deeper part, back-azimuth variation suggests two alternative models, each with an anisotropic layer between two dipping interfaces near 70- and 90-km depth, with fast- and slow-symmetry axes, respectively, above the Apennines slab. Although independent evidence suggests a north-south strike for the slab beneath CUC, the trend of the inferred anisotropy is 45° clockwise from north, inconsistent with a simple downdip shear-coupled flow model in the supra-slab mantle wedge. However complexities of flow and induced rock fabric in the Tyrrhenian back arc may arise due to several concurring factors such as the arcuate shape of the Apennines slab, its retreating kinematics, or slab edge effects.
    Description: Published
    Description: 35-48
    Description: 3.3. Geodinamica e struttura dell'interno della Terra
    Description: JCR Journal
    Description: reserved
    Keywords: Subduction zone processes ; Seismic anisotropy ; Body waves ; Mantle processes ; 04. Solid Earth::04.06. Seismology::04.06.09. Waves and wave analysis
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 18
    Journal cover
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    Eastern European Economics (ältere Jahrgänge via JSTOR)
    M. E. Sharpe | JSTOR
    Online: 1(1).1962 – (older than 6 years)
    Details
    Publisher: M. E. Sharpe , JSTOR
    Print ISSN: 0012-8775
    Electronic ISSN: 1557-9298
    Topics: Economics
    Keywords: JSTOR Archive Collection Business II
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  • 19
    Journal cover
    Unknown
    Public Performance and Management Review (ältere Jahrgänge via JSTOR)
    M. E. Sharpe | JSTOR
    Online: 24(1).2000 – (older than 6 years)
    Details
    Publisher: M. E. Sharpe , JSTOR
    Print ISSN: 1530-9576
    Electronic ISSN: 1557-9271
    Topics: Political Science , Economics
    Keywords: JSTOR Archive Collection Business II
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  • 20
    Journal cover
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    Journal of Post Keynesian Economics (ältere Jahrgänge via JSTOR)
    M. E. Sharpe | JSTOR
    Online: 1(1).1978 – (older than 6 years)
    Details
    Publisher: M. E. Sharpe , JSTOR
    Print ISSN: 0160-3477
    Electronic ISSN: 1557-7821
    Topics: Economics
    Keywords: JSTOR Archive Collection Business II
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  • 21
    Journal cover
    Unknown
    Journal of Advertising (ältere Jahrgänge via JSTOR)
    M. E. Sharpe | JSTOR
    Online: 1(1).1972 – (older than 6 years)
    Details
    Publisher: M. E. Sharpe , JSTOR
    Print ISSN: 0091-3367
    Electronic ISSN: 1557-7805
    Topics: Economics
    Keywords: JSTOR Archive Collection Business II
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  • 22
    Journal cover
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    Financial Management (ältere Jahrgänge via JSTOR)
    Wiley | Financial Management Association International | JSTOR
    Online: 1(1).1972 – (older than 4 years)
    Details
    Publisher: Wiley , Financial Management Association International , JSTOR
    Print ISSN: 0046-3892
    Electronic ISSN: 1755-053X
    Topics: Economics
    Keywords: JSTOR Archive Collection Business II
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  • 23
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    Applied Economic Perspectives and Policy
    Wiley | JSTOR | formerly Oxford University Press (OUP)
    Online: 10(1).1988 –
    Details
    Formerly as: Illinois Agricultural Economics; North Central Journal of Agricultural Economics; Review of Agricultural Economics  (1961–2009)
    Publisher: Wiley , JSTOR , formerly Oxford University Press (OUP)
    Print ISSN: 0191-9016 , 1058-7195 , 2040-5790
    Electronic ISSN: 1467-9353 , 2040-5804
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Economics
    Keywords: JSTOR Archive Collection Business II
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    Scandinavian Journal of Economics, The (ältere Jahrgänge via JSTOR)
    Wiley | JSTOR
    Online: 78.1976 – (older than 6 years)
    Details
    Publisher: Wiley , JSTOR
    Print ISSN: 0347-0520
    Electronic ISSN: 1467-9442
    Topics: Economics
    Keywords: JSTOR Archive Collection Business II
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