- Italy
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Research Interests: Seismology and Algorithm
Seismo-electromagnetic signals are electromagnetic signals generated by the propagation of a seismic wave in a porous media containing fluids (Gao & Hu, 2010).These signals can potentially provide useful information on the poro-elastic... more
Seismo-electromagnetic signals are electromagnetic signals generated by the propagation of a seismic wave in a porous media containing fluids (Gao & Hu, 2010).These signals can potentially provide useful information on the poro-elastic media and the hosted fluids (Garambois & Dietrich, 2002).Thus, there has been a growing interest in the study of SES in recent years, due to their potential.Researchers are focusing both on modelling and analysis of both passive and active experiments to investigate the characteristics of these signals (e.g. Honkura et al., 2000; Matsushima et al., 2002; Warden et al., 2013; Gao et al., 2016; Balasco et al., 2014; Dzieran et al., 2019).Passive experiments involve the observation and analysis of naturally occurring SES triggered by earthquakes, while active experiments involve the controlled generation of these signals using seismic source.The aim of our work is to present the results deriving from the analysis of SES recorded with both approaches. As ...
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<p>The High Agri Valley (HAV) is an intermountain basin, located in the axial zone of Southern Apennines. It is characterized by a very high seismic hazard, as testified by the 1857 M<sub>W</sub>... more
<p>The High Agri Valley (HAV) is an intermountain basin, located in the axial zone of Southern Apennines. It is characterized by a very high seismic hazard, as testified by the 1857 M<sub>W</sub> 7 Basilicata earthquake and by the present widespread seismic activity as well. The strong seismogenic potential of the area is strictly related to the geologic evolution of the Apennines and in turn to its present complex tectonic configuration.</p><p>In addition to the natural low-magnitude seismicity occurring therein, two anthropogenic seismicity clusters are documented, located NE and SW of the artificial Pertusillo lake, respectively: a) fluid-induced microseismic swarms due to the injection, through the Costa Molina 2 well, of the wastewater produced by the exploitation of the Val d’Agri oilfield; b) protracted reservoir induced seismicity (RIS) caused by the combined effects of the water table oscillations of the Pertusillo lake, of the regional tectonics and of the poroelastic/elastic stress due to aquifers in the carbonate rocks.</p><p>In the recent past, the elastic properties of the target area have been thoroughly investigated through velocity tomography studies; nonetheless, the attenuation crustal features are to date almost completely unexplored. In our work we thus aim at starting to fill this scientific gap.</p><p>We here present the preliminary results obtained by applying the coda attenuation method on the seismic dataset collected in the period 2001-2014 by the stations belonging to both the trigger-mode monitoring network managed by ENI Oil Company and the Italian National Seismic Network managed by INGV. The complete seismic catalogue consists of about 1800 earthquakes in the magnitude range Ml 0 – 3.3 recorded by an average number of 14 stations. We show the unprecedented Q-coda estimations in the area. This information, in the first order Born approximation, represents the total attenuation accounting for both the scattering (Q<sub>S</sub>) and the intrinsic quality factor (Q<sub>i</sub>). </p><p>The preliminary results retrieved in this study are intended to be the first step towards a complete comprehension of the attenuation properties in this area by including in the near future also the continuous data recorded by the recently installed dense seismic network belonging to the HAV geophysical Observatory (HAVO). The planned investigation will pave the way to the discrimination between the scattering effects and anelastic features acting on the seismic waves propagating within the seismogenic crust of the study area. In that way it will be possible to better identify structural discontinuities and to gain further insights into the role of fluids in the preparatory phase and nucleation of earthquakes in the HAV.</p>
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Historical seismic catalogs report that the Gargano Promontory (southern Italy) was affected in the past by earthquakes with medium to high estimated magnitude. From the instrumental seismicity, it can be identified that the most... more
Historical seismic catalogs report that the Gargano Promontory (southern Italy) was affected in the past by earthquakes with medium to high estimated magnitude. From the instrumental seismicity, it can be identified that the most energetic Apulian sequence occurred in 1995 with a main shock of MW = 5.2 followed by about 200 aftershocks with a maximum magnitude of 3.7. The most energetic earthquakes of the past are attributed to right-lateral strike-slip faults, while there is evidence that the present-day seismicity occur on thrust or thrust-strike faults. In this article, we show a detailed study on focal mechanisms and stress field obtained by micro-seismicity recorded from April 2013 until the present time in the Gargano Promontory and surrounding regions. Seismic waveforms are collected from the OTRIONS Seismic Network (OSN), from the Italian National Seismic Network (RSN), and integrated with data from the Italian National Accelerometric Network (RAN) in order to provide a robu...
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We consider a thermo-rheological model made of a viscoelastic half-space with Maxwell rheology and temperature-dependent viscosity. The half-space is made of layers with different values of density, thermal conductivity, activation energy... more
We consider a thermo-rheological model made of a viscoelastic half-space with Maxwell rheology and temperature-dependent viscosity. The half-space is made of layers with different values of density, thermal conductivity, activation energy and heat productivity. The model relates the surface heat flow to the depth of the brittle-ductile transition and the thickness of the seismogenic layer. The model is applied to the Gargano area (Italy) which is subject to a frequent low-magnitude seismic activity, although it lies out of the Apennine axis, which is the main Italian seismogenic area. The seismic activity in the Gargano area and surroundings occurs at depths that are systematically different in the north-eastern zone with respect to the south-western zone. In correspondence with the change in depth of earthquake foci, we observe a change in the value of surface heat flow. Starting from these observations and from the knowledge of the lithospheric structure, we propose two different geotherms for the two zones. Assuming a constant strain rate, the shear stress is computed as a function of depth and the thickness of the seismogenic layer in the two zones is inferred. The comparison of the results of the thermo-rheological model with the seismological observation is good.
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he attenuation of coda and S waves has been inferred for the Umbria-Marche region (central Italy) using seismic waveforms collected during the 1997 seismic crisis. The selected dataset is composed of 343 small magnitude (1.4... more
he attenuation of coda and S waves has been inferred for the Umbria-Marche region (central Italy) using seismic waveforms collected during the 1997 seismic crisis. The selected dataset is composed of 343 small magnitude (1.4 <ML<4.2) earthquakes recorded at a temporary array composed of 23 seismic stations. The Sato (1977) method, based on the assumption of single isotropic scattering has been used to infer Qc, considering three different lapse times (20, 30 and 40 s). The coda normalization method (Aki, 1980) has been used to infer Q. Both Qc and Qshow a clear frequency dependence with a different frequency dependent parameter. The frequency dependence of Qc is comparable with that previously found in the same area and around it. Using the method of Wennerberg (1993), intrinsic and scattering attenuation have been separated. Intrinsic attenuation is found to be close to coda attenuation and dominates over scattering dissipation. Coda Q increases with increasing lapse time ...
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290 low magnitude earthquakes (0.6 &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; Ml &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 3.5), recorded in South-eastern Sicily (Italy) by a local network deployed in... more
290 low magnitude earthquakes (0.6 &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; Ml &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 3.5), recorded in South-eastern Sicily (Italy) by a local network deployed in the area by the Istituto Nazionale di Geofisica e Vulcanologia (ex Poseidon System), have been selected on the basis of the quality of the shape of the first P arrival. Plots of rise times and pulse widths at each station
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Conduit exit conditions during explosive eruptions play a major role in determining the rate and style of the eruptive column. The main parameter characterizing the eruptive mixture at conduit exit is mass eruption rate (MER), which is... more
Conduit exit conditions during explosive eruptions play a major role in determining the rate and style of the eruptive column. The main parameter characterizing the eruptive mixture at conduit exit is mass eruption rate (MER), which is the product of velocity, density and conduit section area. This was perceived by the first researchers, who constructed theoretical model on the dynamics of explosive eruptions (Wilson et al., 1980; Woods, 1988; Bursik and Woods, 1991). Numerical modelling also helped scientists in the understanding of the complex dynamics of this kind of eruptions (Macedonio et al., 2005; Neri et al., 1998; Papale, 2001; Papale et al., 1998). Finally, the first large scale experiments on the mechanics of eruptive columns and pyroclastic flows (Dellino et al., 2007) allowed the development of an empirical model for the prediction of exit velocity of eruptive mixtures and the conditions of existence of the main eruptive styles (Dellino et al., 2009). Since the experiments were successfully scaled to real eruptions, we implemented a numerical model that reproduces the main quantities measured in the experiments, with the aim of eventually extending the model to the natural case. This would be the first time that a numerical model on the mechanics of explosive eruptions is validated against large-scale experiments. A steady 1-D two phase numerical model of the conduit flow is presented here. In this model the equations of conservation of mass and momentum for gas and volcanic particles are solved via a Runge-Kutta method with an adaptive stepsize. The numerical model is implemented in a code written in Fortran 77 language. The use of an adaptive stepsize control over the Runge-Kutta method allows the achievement of a predetermined accuracy (in this case of the order of 10-5) with minimum computational effort. All the conditions of the experimental runs are implemented and the velocity field is initialized using the empirical model for mixture velocity (Dellino et al., 2009). The model takes in account the real shape of volcanic ash and uses the well established law of Dellino et al. (2005) for the calculation of particles' terminal velocity. The pressure gradient in the conduit, which represents the main driving force of the vertical two-phase flow, is obtained by the same empirical model (Dellino et al., 2009). Finally the interphase drag force and the friction between the phases and the conduit wall are included: the classic empirical laws for wall-particles and wall-fluid frictions developed in industrial engineering and classic fluid dynamics are implemented in the code. All the experimental runs have been simulated with the numerical code, and the model results in velocities that are quite consistent with experiments.
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ABSTRACT Mt. Vesuvius is an active volcano famous for the AD 79 eruption that destroyed Pompeii, Herculaneum and Stabiae. Because of the intense urbanization around and on the volcano, the risk today is very high. Therefore, the knowledge... more
ABSTRACT Mt. Vesuvius is an active volcano famous for the AD 79 eruption that destroyed Pompeii, Herculaneum and Stabiae. Because of the intense urbanization around and on the volcano, the risk today is very high. Therefore, the knowledge of the structure and behavior of the magmatic system is fundamental both for the interpretation of any change in the dynamics of the volcano and for prediction of eruptions. A review of available and new isotopic data on rocks from Mt. Vesuvius, together with mineralogical and geochemical data and recent geophysical results, allow us to constrain a thermal modeling that describes history and present state of Mt. Vesuvius magmatic system. This system is formed by a &quot;deep&quot;, complex magmatic reservoir where mantle-derived magmas arrive, stagnate and differentiate. The reservoir extends discontinuously between 10 and 20 km of depth, is hosted in densely fractured crustal rocks, where magmas and crust can interact, and has been fed more than once since 400 ka. The hypothesis of crustal contamination is favored by the high temperatures reached by crustal rocks as a consequence of repetitive intrusions of magma. From the &quot;deep&quot; reservoir magmas of K-basaltic to K-tephritic to K-phonotephritic composition rise to shallow depths where they stagnate at 3-5 km of depth before plinian eruptions, and through crystallization and mixing processes with the residual portion of the feeding systems, generate isotopically and geochemically layered reservoirs. Alternatively, during &quot;open conduit&quot; conditions deep, volatile-rich magma batches rise from the &quot;deep&quot; reservoir to less than 1 km of depth and mix with the crystal-rich, volatile-poor resident magma, triggering eruptions.
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Abstract—Among Q-estimation methods a simple linear technique consists of the evaluation of the increasing rise time of body waves with the increase of their travel time. This method, known as the rise time method, was theoretically... more
Abstract—Among Q-estimation methods a simple linear technique consists of the evaluation of the increasing rise time of body waves with the increase of their travel time. This method, known as the rise time method, was theoretically justified for an impulsive source time function (Dirac delta function). Wu and Lees (1996), throughout finite difference calculations, showed that, when considering finite source time functions, characterized by a cut-off frequency around 20 Hz, the rise time method can be satisfactorily applied to invert earthquake data.¶In order to establish the applicability of the rise time method to an arbitrary earthquake source we analytically solved the problem of the propagation, throughout an anelastic medium, of a signal generated by a finite dimensions seismic source the shear dislocation fault of Brune (1970). Analyzing theoretical rise time vs. travel-time curves, we were able to distinguish two different corner frequency ranges in which the trend is different. When corner frequency is below 10 Hz the discrepancies with the rise time method increase with a decrease of the corner frequency. When corner frequency is above 10 Hz no meaningful differences are observed.¶The application of the model to a synthetic data set, based on the sources-receivers configuration of the 15 November 1995 Border Town, Nevada, earthquake sequence, shows that a significant bias affects Q estimates obtained with the rise time method, for seismic events characterized by a Brune corner frequency less than 5 Hz.
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The dataset includes the seismic energy envelopes used to study the coda attenuation Qc quality factor in the Gargano Promontory (Southern Italy) and surrounding regions (Filippucci et al., 2019; 2021). The seismic energy envelopes are... more
The dataset includes the seismic energy envelopes used to study the coda attenuation Qc quality factor in the Gargano Promontory (Southern Italy) and surrounding regions (Filippucci et al., 2019; 2021). The seismic energy envelopes are band pass filtered (Butterworth, two-poles) in frequency bands with central frequency fc= 2, 3, 4, 5, 6, 8, 10, 12, 14 and 16 Hz, with a bandwidth ranging inside the interval [fc/√2; fc*√2]. Seismic envelopes are already cut in the time window of the descending energy, ready to be fitted in order to compute the seismic energy attenuation of the sampled medium. In order to reproduce the results of the Qc study (Filippucci et al., 2019; 2021) a single scattering model (Aki, 1969) should be used. - For earthquakes occurred from June to September 2013 the folder is Seismic_Envelopes_2013.zip. In this compressed folder, the seismic event folders are collected named with a numerical code indicating year, month, day, hour, minute of the event origin time (format AAAAMMDDHHmm). In each event folder, the seismic envelope files in *.dat format. - For earthquakes occurred from July 2015 to August 2018 the folder is Seismic_Envelopes_2015_2018.zip. In this compressed folder, the seismic event folders are collected named with a numerical code indicating year, month, day, hour, minute of the event origin time (format AAAAMMDDHHmm). In each event folder, the seismic envelope files in *.TXT format. The original seismograms together with the event's location and magnitude, station locations and velocity model have been already published (https://data.mendeley.com/datasets/7b5mmdjpt3/5).
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Database of the collected waveforms of microearthquakes occurred in the Gargano region (Southern Italy), recorded by the stations of the National Seismic Network (RSN-INGV) and by the Gargano seismic network (OTRIONS) in the period... more
Database of the collected waveforms of microearthquakes occurred in the Gargano region (Southern Italy), recorded by the stations of the National Seismic Network (RSN-INGV) and by the Gargano seismic network (OTRIONS) in the period 2013/04/15 to 2018/08/05, and that integrates the INGV catalogue (http://cnt.rm.ingv.it/). Database of the recognized earthquakes. The University of Bari (Italy) in cooperation with the National Institute of Geophysics and Volcanology (INGV) (Italy), deployed, in 2013, the OTRIONS micro-earthquake network aiming to better understand the active tectonics of the Gargano promontory (Southern Italy). The network consists of 12 short period 3 component seismic stations located in the Apulian territory (Southern Italy). This data releases regards the waveform database collected from 2013 up to 2018. At the end of 2018, we implemented a cloud infrastructure to make more robust the acquisition and storage system of the network through a collaboration with the RECAS-Bari computing centre of the University of Bari (Italy) and of the National Institute of Nuclear Physics (Italy). From the beginning of 2019 waveform dataset and the station metadata are accessible through the European Integrated Data Archive.
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Here, we describe the dataset of seismic envelopes used to study the S-wave Q-coda attenuation quality factor Qc of the Gargano Promontory (Southern Italy). With this dataset, we investigated the crustal seismic attenuation by the Qc... more
Here, we describe the dataset of seismic envelopes used to study the S-wave Q-coda attenuation quality factor Qc of the Gargano Promontory (Southern Italy). With this dataset, we investigated the crustal seismic attenuation by the Qc parameter. We collected this dataset starting from two different earthquake catalogues: the first regarding the period from April 2013 to July 2014; the second regarding the period from July 2015 to August 2018. Visual inspection of the envelopes was carried out on recordings filtered with a Butterworth two-poles filter with central frequency fc = 6 Hz. The obtained seismic envelopes of coda decay can be linearly fitted in a bilogarithmic diagram in order to obtain a series of single source-receiver measures of Qc for each seismogram component at different frequency fc. The analysis of the trend Qc(fc) gives important insights into the heterogeneity and the anelasticity of the sampled Earth medium.
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We investigate crustal seismic attenuation by the coda quality parameter (Qc) in the Gargano area (Southern Italy), using a recently released dataset composed of 191 small earthquakes (1.0 ≤ ML ≤ 2.8) recorded by the local OTRIONS and the... more
We investigate crustal seismic attenuation by the coda quality parameter (Qc) in the Gargano area (Southern Italy), using a recently released dataset composed of 191 small earthquakes (1.0 ≤ ML ≤ 2.8) recorded by the local OTRIONS and the Italian INGV seismic networks, over three years of seismic monitoring. Following the single back-scattering theoretical assumption, Qc was computed using different frequencies (in the range of 2–16 Hz) and different lapse times (from 10 to 40 s). The trend of Qc vs. frequency is the same as that observed in the adjacent Umbria-Marche region. Qc at 1 Hz varies between 11 and 63, indicating that the area is characterized by active tectonics, despite the absence of high-magnitude earthquakes in recent decades. The 3D mapping procedure, based on sensitivity kernels, revealed that the Gargano Promontory is characterized by very low and homogeneous Qc at low frequencies, and by high and heterogeneous Qc at high frequencies. The lateral variations of Qc a...
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The historical seismicity catalogs report that the Gargano area (Apulia region, southern Italy) has been site of medium to high magnitude earthquakes. Instrumental seismicity suffers of the poor coverage of the seismic stations of the RSN... more
The historical seismicity catalogs report that the Gargano area (Apulia region, southern Italy) has been site of medium to high magnitude earthquakes. Instrumental seismicity suffers of the poor coverage of the seismic stations of the RSN (National Seismic Network). To improve the seismological monitoring of the area, in 2013 the OTRIONS seismic network (OSN), managed by the University of Bari - Italy, in cooperation with INGV (National Institute of Geophysics and Volcanology), was installed. In this study, focal mechanisms of single and composite events have been computed using 118 micro-earthquakes occurred in this area. We subdivided the dataset into subsets according to their location and depth, distinguishing between the Promontory zone and the Apulian foredeep. High quality focal mechanisms and low-misfit stress tensor inversion were obtained for three groups of events. To better constrain the stress tensor we included also focal mechanism solutions obtained in previous studies. In the southwestern Apulian foredeep zone, a normal fault kinematics is inferred, normal to the Apennine stress direction; in the Promontory zone, the fault kinematics indicate inverse fault mechanisms striking in NE-SW direction. Differently from previous analyses, the stress orientations inferred in this study agree with those inferred in the World Stress Map.