Large variations of the CO2 flux through the soil were observed between November 2002 and January... more Large variations of the CO2 flux through the soil were observed between November 2002 and January 2006 at Mt. Etna volcano. In many cases, the CO2 flux was strongly influenced by changes in air temperature and atmospheric pressure. A new filtering method was then developed to remove the atmospheric influences on soil CO2 flux and, at the same time, to
We investigated the relationship between volcano-seismic events, recorded at La Fossa crater of V... more We investigated the relationship between volcano-seismic events, recorded at La Fossa crater of Vulcano (Aeolian Islands, Italy) during 2004-2006, and the dynamics of the hydrothermal system. During the period of study, three episodes of increasing numbers of volcano-seismic events took place at the same time as geothermal and geochemical anomalies were observed. These geothermal and geochemical anomalies have been interpreted
1 the deCemBer 2015 and maY 2016 eruPtIons at mt. etna: InsIght on volCano PlumBIng sYstem struCt... more 1 the deCemBer 2015 and maY 2016 eruPtIons at mt. etna: InsIght on volCano PlumBIng sYstem struCture and geometrY BY a multIdIsCIPlInarY aPProaCh A. Cannata1,2, G. Di Grazia2, M. Giuffrida3, S. Gresta3, M. Palano2, M. Sciotto2, M. Viccaro3,2, F. Zuccarello3 1 Dipartimento di Fisica e Geologia, Università degli Studi di Perugia, Italy 2 2Istituto Nazionale di Geofisica e Vulcanologia, Osservatorio Etneo, Catania, Italy 3 Dipartimento di Scienze Biologiche, Geologiche e Ambientali, Università degli Studi, Catania, Italy
the tethyan roots of southeastern siciLy (itaLy): an interdiscipLinary insight from new 3d seismi... more the tethyan roots of southeastern siciLy (itaLy): an interdiscipLinary insight from new 3d seismic tomographies and petrophysicaL inferences E. Giampiccolo1, A. Brancato1, F.C. Manuella2, S. Carbone2, S. Gresta2, V. Scribano2 1 Istituto Nazionale di Geofisica e Vulcanologia – Osservatorio Etneo, Catania, Italy 2 Dip. Scienze Biologiche, Geologiche e Ambientali, Sezione di Scienze della Terra, Università di Catania, Italy
Nakamuras technique, or the H/V spectral ratio method, has been applied to microtremor measureme... more Nakamuras technique, or the H/V spectral ratio method, has been applied to microtremor measurements carried out in the urban area of Catania (Eastern Sicily) to obtain information on the geological structure of some sites,and to make a hypothesis on their seismic response. In general, sites located on soft soils or anthropic debris fillings have shown greater amplification at high frequencies (above 1 Hz). However, a strong lateral variation was observed in the frequency band, thus a denser grid of measurement points is necessary for a precise mapping of the resonant frequencies. In the low frequency range, between 0.1 and 1 Hz, a common peak around 0.2 Hz was observed. The fundamental resonant frequency inferred from the main peak in the H/V spectrum has been used to calculate the depth of the interface between the clays and the main reflector on the basis of the shear-wave velocity: it has been estimated as about 700 m.
Tectonic stress in the Pacific Northwest Washington is dominated by a N-S major compressive axis ... more Tectonic stress in the Pacific Northwest Washington is dominated by a N-S major compressive axis s1 and a minor compressive axis s3 which varies from E-W to near vertical. Minor variations in this pattern occur in different parts of the region. In this study we used ca. 550 earthquakes in the central Washington Cascade Mountains to study in detail the uniformity of the stress tensor in this volcanic arc. Earthquakes from the Pacific Northwest Seismograph Network (PNSN) catalogue were divided into several subsets based on epicentral and depth groupings and stress-tensor inversions using the Gephart and Forsyth technique were computed for each group. As in previous similar studies the maximum compressive stress axis (s1) is nearly horizontal and trending ca. N-S and NNE-SSW in all but one subset. Shallower events directly under Mount Rainier have a near vertical s1. For other subsets the minimum compressive stress axis (s3) deviates from vertical to horizontal for different groups of ...
It is well known that in a volcanic region the mechanical behaviour of the shallow crust differs ... more It is well known that in a volcanic region the mechanical behaviour of the shallow crust differs significantly from that of a tectonic extensional area because of high rock fragmentation and heterogeneity. This affects the capability of the medium for storing energy, the size and rate of earthquakes, and the dimension of seismic sources. Computing seismic source parameters allows a
ABSTRACT In the last 1000 years southeastern Sicily was struck by large seismic events (1169, 154... more ABSTRACT In the last 1000 years southeastern Sicily was struck by large seismic events (1169, 1542, 1693, 1757, 1846 and 1990). Following the 1990 earthquake (Ml=5.4), the monitoring of seismic activity of the iblean foreland has been improved by nine 3-C digital seismic stations run by INGV (Sezione di Catania). As inferred from the records of the years 1994-2002, the seismic activity was characterized by events of small magnitudes which did not exceed M=4.2. From the collected seismic database, 70 events with at least 7 impulsive P-wave first motions, were selected. Routine earthquake locations were obtained by using the program Hypoellipse (Lahr, 1989) in an six layers, one-dimensional velocity structure. The depth distribution shows that the majority of the selected events are shallower than 25 km. To estimate the fault parameters of these events a non linear inversion method, which uses both polarity and S polarization data sets (Zollo and Bernard, 1991), has been used. The azimuth, the polarization and the incidence angles of P- and S-waves have been determined applying a Covariance Matrix Decomposition (Montalbetti and Kanasewich, 1970). The addition of a few S polarizations to a set of P polarities greatly improved the resolution of the fault parameters, reducing also the number of multiple solutions. In agreement with the focal mechanism obtained for the 1990 earthquake, compressional axes (P) are mostly oriented NW-SE. Moreover, the analysis of shear-wave splitting shows the polarization of the fast S-wave along the same direction (NW-SE). Finally, earthquakes have been analyzed in order to determine the stress tensor directions by using Gephart and Forsyth algorithm. References Lahr, J.C. (1989). Hypoellipse/version 2.0: A computer program for determining local earthquake hypocentral parameters, magnitude and first motion pattern. U.S. Geol. Surv., Open-File Rep. 89/116, 81 pp. Montalbetti, J. F., and E. R. Kanasevich (1970). Enhancement of telesismic body phase with a polarization filter. Geophys. J. R. Astron. Soc., 21, 119-129. Zollo, A. and P. Bernard (1991). Fault mechanism for near source data: joint inversion of P polarities and S polarizations. Geophys. J. Int., 104, 441-452.
Very long period signals (VLP, 10 s-30 s) associated with long period events (0.5 Hz-5 Hz) were o... more Very long period signals (VLP, 10 s-30 s) associated with long period events (0.5 Hz-5 Hz) were observed at Etna Volcano, Italy, during June-November 2005. They are only recorded at the broadband stations nearest to Etna's craters, ECPN, EBEL, EPDN and EPLC. These ...
Abstract Seismic activity, ground deformation, and soil and fumarole temperatures acquired during... more Abstract Seismic activity, ground deformation, and soil and fumarole temperatures acquired during 20042007 at Vulcano (Aeolian Islands) are analysed and the time relations among the different time series are discussed. Changes in temperature of fumarolic gases took ...
Large variations of the CO2 flux through the soil were observed between November 2002 and January... more Large variations of the CO2 flux through the soil were observed between November 2002 and January 2006 at Mt. Etna volcano. In many cases, the CO2 flux was strongly influenced by changes in air temperature and atmospheric pressure. A new filtering method was then developed to remove the atmospheric influences on soil CO2 flux and, at the same time, to
We investigated the relationship between volcano-seismic events, recorded at La Fossa crater of V... more We investigated the relationship between volcano-seismic events, recorded at La Fossa crater of Vulcano (Aeolian Islands, Italy) during 2004-2006, and the dynamics of the hydrothermal system. During the period of study, three episodes of increasing numbers of volcano-seismic events took place at the same time as geothermal and geochemical anomalies were observed. These geothermal and geochemical anomalies have been interpreted
1 the deCemBer 2015 and maY 2016 eruPtIons at mt. etna: InsIght on volCano PlumBIng sYstem struCt... more 1 the deCemBer 2015 and maY 2016 eruPtIons at mt. etna: InsIght on volCano PlumBIng sYstem struCture and geometrY BY a multIdIsCIPlInarY aPProaCh A. Cannata1,2, G. Di Grazia2, M. Giuffrida3, S. Gresta3, M. Palano2, M. Sciotto2, M. Viccaro3,2, F. Zuccarello3 1 Dipartimento di Fisica e Geologia, Università degli Studi di Perugia, Italy 2 2Istituto Nazionale di Geofisica e Vulcanologia, Osservatorio Etneo, Catania, Italy 3 Dipartimento di Scienze Biologiche, Geologiche e Ambientali, Università degli Studi, Catania, Italy
the tethyan roots of southeastern siciLy (itaLy): an interdiscipLinary insight from new 3d seismi... more the tethyan roots of southeastern siciLy (itaLy): an interdiscipLinary insight from new 3d seismic tomographies and petrophysicaL inferences E. Giampiccolo1, A. Brancato1, F.C. Manuella2, S. Carbone2, S. Gresta2, V. Scribano2 1 Istituto Nazionale di Geofisica e Vulcanologia – Osservatorio Etneo, Catania, Italy 2 Dip. Scienze Biologiche, Geologiche e Ambientali, Sezione di Scienze della Terra, Università di Catania, Italy
Nakamuras technique, or the H/V spectral ratio method, has been applied to microtremor measureme... more Nakamuras technique, or the H/V spectral ratio method, has been applied to microtremor measurements carried out in the urban area of Catania (Eastern Sicily) to obtain information on the geological structure of some sites,and to make a hypothesis on their seismic response. In general, sites located on soft soils or anthropic debris fillings have shown greater amplification at high frequencies (above 1 Hz). However, a strong lateral variation was observed in the frequency band, thus a denser grid of measurement points is necessary for a precise mapping of the resonant frequencies. In the low frequency range, between 0.1 and 1 Hz, a common peak around 0.2 Hz was observed. The fundamental resonant frequency inferred from the main peak in the H/V spectrum has been used to calculate the depth of the interface between the clays and the main reflector on the basis of the shear-wave velocity: it has been estimated as about 700 m.
Tectonic stress in the Pacific Northwest Washington is dominated by a N-S major compressive axis ... more Tectonic stress in the Pacific Northwest Washington is dominated by a N-S major compressive axis s1 and a minor compressive axis s3 which varies from E-W to near vertical. Minor variations in this pattern occur in different parts of the region. In this study we used ca. 550 earthquakes in the central Washington Cascade Mountains to study in detail the uniformity of the stress tensor in this volcanic arc. Earthquakes from the Pacific Northwest Seismograph Network (PNSN) catalogue were divided into several subsets based on epicentral and depth groupings and stress-tensor inversions using the Gephart and Forsyth technique were computed for each group. As in previous similar studies the maximum compressive stress axis (s1) is nearly horizontal and trending ca. N-S and NNE-SSW in all but one subset. Shallower events directly under Mount Rainier have a near vertical s1. For other subsets the minimum compressive stress axis (s3) deviates from vertical to horizontal for different groups of ...
It is well known that in a volcanic region the mechanical behaviour of the shallow crust differs ... more It is well known that in a volcanic region the mechanical behaviour of the shallow crust differs significantly from that of a tectonic extensional area because of high rock fragmentation and heterogeneity. This affects the capability of the medium for storing energy, the size and rate of earthquakes, and the dimension of seismic sources. Computing seismic source parameters allows a
ABSTRACT In the last 1000 years southeastern Sicily was struck by large seismic events (1169, 154... more ABSTRACT In the last 1000 years southeastern Sicily was struck by large seismic events (1169, 1542, 1693, 1757, 1846 and 1990). Following the 1990 earthquake (Ml=5.4), the monitoring of seismic activity of the iblean foreland has been improved by nine 3-C digital seismic stations run by INGV (Sezione di Catania). As inferred from the records of the years 1994-2002, the seismic activity was characterized by events of small magnitudes which did not exceed M=4.2. From the collected seismic database, 70 events with at least 7 impulsive P-wave first motions, were selected. Routine earthquake locations were obtained by using the program Hypoellipse (Lahr, 1989) in an six layers, one-dimensional velocity structure. The depth distribution shows that the majority of the selected events are shallower than 25 km. To estimate the fault parameters of these events a non linear inversion method, which uses both polarity and S polarization data sets (Zollo and Bernard, 1991), has been used. The azimuth, the polarization and the incidence angles of P- and S-waves have been determined applying a Covariance Matrix Decomposition (Montalbetti and Kanasewich, 1970). The addition of a few S polarizations to a set of P polarities greatly improved the resolution of the fault parameters, reducing also the number of multiple solutions. In agreement with the focal mechanism obtained for the 1990 earthquake, compressional axes (P) are mostly oriented NW-SE. Moreover, the analysis of shear-wave splitting shows the polarization of the fast S-wave along the same direction (NW-SE). Finally, earthquakes have been analyzed in order to determine the stress tensor directions by using Gephart and Forsyth algorithm. References Lahr, J.C. (1989). Hypoellipse/version 2.0: A computer program for determining local earthquake hypocentral parameters, magnitude and first motion pattern. U.S. Geol. Surv., Open-File Rep. 89/116, 81 pp. Montalbetti, J. F., and E. R. Kanasevich (1970). Enhancement of telesismic body phase with a polarization filter. Geophys. J. R. Astron. Soc., 21, 119-129. Zollo, A. and P. Bernard (1991). Fault mechanism for near source data: joint inversion of P polarities and S polarizations. Geophys. J. Int., 104, 441-452.
Very long period signals (VLP, 10 s-30 s) associated with long period events (0.5 Hz-5 Hz) were o... more Very long period signals (VLP, 10 s-30 s) associated with long period events (0.5 Hz-5 Hz) were observed at Etna Volcano, Italy, during June-November 2005. They are only recorded at the broadband stations nearest to Etna's craters, ECPN, EBEL, EPDN and EPLC. These ...
Abstract Seismic activity, ground deformation, and soil and fumarole temperatures acquired during... more Abstract Seismic activity, ground deformation, and soil and fumarole temperatures acquired during 20042007 at Vulcano (Aeolian Islands) are analysed and the time relations among the different time series are discussed. Changes in temperature of fumarolic gases took ...
Uploads
Papers