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  • 05. General::05.01. Computational geophysics::05.01.04. Statistical analysis  (4)
  • Wiley-Blackwell  (4)
  • Nature Publishing Group
  • 2010-2014  (4)
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Year
  • 1
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    Some insights on the occurrence of recent volcanic eruptions of Mount Etna volcano (Sicily, Italy) (2012)
    Wiley-Blackwell
    Details
    Publication Date: 2017-04-03
    Description: In the first part of this work, we make use of two non-parametric statistical pattern recognition algorithms and a multiple regression analysis to analyse seismic clusters occur ring around Mount Etna, Italy. The aim is to determine if the onset of flank eruptions at Mount Etna is linked to variations in the regional seismicity at a timescale of few weeks. From the analysis, we find that the discrimination between clusters preceding flank eruptions and clusters not related in time to flank activity is mainly linked to the volume output of the previous flank eruption, in some cases together with the time elapsed from its end. Instead, we do not find any difference in the seismicity features characterizing different types of clusters, except for a very small contribution of the number of seismic events in the clusters. This result does not confirm the existence, suggested in the past, of a direct link between the regional state of stress at a timescale of few weeks and the occurrence of flank eruptions on Mount Etna volcano. On the contrary, the result suggests that a prominent role in the flank eruption occur rence is played by the re-charging of the feeding system. In the second part of this study we analyse the relationship between the magma volume erupted in an eruption and the interevent time following it, finding that a ‘time-predictable model’ satisfactorily describes the occurrence of eruptions at Mount Etna in the last decades. The latter analysis is car ried out both on the flank eruption catalogue only, and on the complete catalogue of flank and summit eruptions, with comparable results.
    Description: Published
    Description: 1203–1218
    Description: JCR Journal
    Description: restricted
    Keywords: flank eruptions ; Mount Etna volcano ; regional tectonic stress ; statistical pattern recognition ; time predictability ; 05. General::05.01. Computational geophysics::05.01.04. Statistical analysis
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 2
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    Are the source models of the M7.1 1908 Messina Straits earthquake reliable? Insights from a novel inversion and a sensitivity analysis of levelling data (2013)
    Wiley-Blackwell
    Details
    Publication Date: 2017-04-04
    Description: For decades, many authors have attempted to define the location, geometry and kinematics of the causative fault for the 1908 December 28, M 7.1 earthquake that struck the Messina Straits between Sicily and Calabria (southern Italy). The coseismic displacement caused a predominant downwarping of the Straits and small land uplift away from it, which were documented by levelling surveys performed 1 yr before and immediately after the earthquake. Most of the source models based on inversion of levelling data suggested that the earthquake was caused by a low angle, east-dipping blind normal fault, whose upper projection intersects the Earth surface on the Sicilian (west) side of the Messina Straits.An alternative interpretation holds that the causative fault is one of the high-angle, west-dipping faults located in southern Calabria, on the eastern side of the Straits, and may in large part coincide with the mapped Armo Fault. Here, we critically review the levelling data with the aim of defining both their usefulness and limits in modelling the seismogenic fault. We demonstrate that the levelling data alone are not capable of discriminating between the two oppositely dipping fault models, and thus their role as a keystone for modellers is untenable. However, new morphotectonic and geodetic data indicate that the Armo Fault has very recent activity and is accumulating strain. The surface observations, together with appraisal ofmacroseismic intensity distribution, available seismic tomography and marine geophysical evidence, lends credit to the hypothesis that the Armo and possibly the S. Eufemia faults are part of a major crustal structure that slipped during the 1908 earthquake.
    Description: Published
    Description: 1025-1041
    Description: JCR Journal
    Description: restricted
    Keywords: Earthquake source ; Messina Straits ; 04. Solid Earth::04.03. Geodesy::04.03.01. Crustal deformations ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics ; 05. General::05.01. Computational geophysics::05.01.03. Inverse methods ; 05. General::05.01. Computational geophysics::05.01.04. Statistical analysis
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 3
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    A comparison of moment magnitude estimates for the European–Mediterranean and Italian regions (2013)
    Wiley-Blackwell
    Details
    Publication Date: 2017-04-04
    Description: With the goal of constructing a homogeneous data set of moment magnitudes (Mw) to be used for seismic hazard assessment, we compared Mw estimates from moment tensor catalogues available online. We found an apparent scaling disagreement between Mw estimates from the National Earthquake Information Center (NEIC) of the US Geological Survey and from the Global Centroid Moment Tensor (GCMT) project. We suspect that this is the effect of an underestimation ofMw 〉 7.0 (M0 〉 4.0 × 1019 Nm) computed by NEIC owing to the limitations of their computational approach. We also found an apparent scaling disagreement between GCMT and two regional moment tensor catalogues provided by the ‘Eidgen¨ossische Technische Hochschule Z¨urich’ (ETHZ) and by the European–Mediterranean Regional Centroid Moment Tensor (RCMT) project of the Italian ‘Istituto Nazionale di Geofisica e Vulcanologia’ (INGV). This is probably the effect of the overestimation of Mw 〈 5.5 (M0 〈 2.2 × 1017 Nm), up to year 2002, and of Mw 〈 5.0 (M0 〈 4.0 × 1016 Nm), since year 2003, owing to the physical limitations of the standard CMT inversion method used by GCMT for the earthquakes of relatively low magnitude. If the discrepant data are excluded from the comparisons, the scaling disagreements become insignificant in all cases. We observed instead small absolute offsets (≤0.1 units) for NEIC and ETHZ catalogues with respect to GCMT whereas there is an almost perfect correspondence between RCMT and GCMT. Finally, we found a clear underestimation of about 0.2 units of Mw magnitudes computed at the INGV using the time-domain moment tensor (TDMT) method with respect to those reported by GCMT and RCMT. According to our results, we suggest appropriate offset corrections to be applied to Mw estimates from NEIC, ETHZ and TDMT catalogues before merging their data with GCMT and RCMT catalogues. We suggest as well to discard the probably discrepant data from NEIC and GCMT if other Mw estimates from different sources are available for the same earthquakes. We also estimate approximately the average uncertainty of individual Mw estimates to be about 0.07 magnitude units for the GCMT, NEIC, RCMT and ETHZ catalogues and about 0.13 for the TDMT catalogue.
    Description: European Union research project SHARE (Seismic Hazard Harmonization in Europe), within the ambit of Task 3.1 ‘European Earthquake Database’
    Description: Published
    Description: 1733-1745
    Description: JCR Journal
    Description: restricted
    Keywords: Earthquake source observations; Statistical seismology ; 05. General::05.01. Computational geophysics::05.01.04. Statistical analysis
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 4
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    Crustal heterogeneity highlighted by spatial b-value map in theWellington region of New Zealand (2010)
    Wiley-Blackwell
    Details
    Publication Date: 2017-04-04
    Description: We map the b-value in the subduction zone of theWellington region, NewZealand, using a high quality earthquake catalogue relocated with a 3-D seismic velocity model, consisting of 50 314 events that occurred between 1990 and 2005. In order to investigate heterogeneity in the crust of the overlying plate and in the upper plane of the Wadati–Benioff Zone (WBZ), we analyse a series of cross-sections perpendicular to the strike of the subduction zone. We calculate the b-values selecting events with magnitude of completeness ≥2.4 and depth ≤65 km and projecting the seismicity within 20 km on each side of the cross-sectional planes. We observe areas of high b-value (∼1.7) near the plate interface and regions of low b-value anomalies are detected both in the WBZ in the northwest region below 40 km depth and in the overlying plate in the northern South Island at 10 km depth. The anomalies are statistically significant based on Utsu’s p-test and the bootstrap method and are not data processing method or parameter dependent. We compare the b-value distribution with previously determined 3-D distributions of Vp, Vp/Vs andQp from seismic tomography. This comparison suggests that material inhomogeneity, caused by fluid filled cracks resulting from dehydration of the subducted slab and subducted sediments, is the predominant cause of b-value variation in the shallow part of this subduction zone. Our observations are consistent with a previously proposed conceptual model that fluid distribution in the shallow part of this subduction zone is controlled by the permeability of geological terranes in the overlying plate.
    Description: Published
    Description: 451-460
    Description: 3.3. Geodinamica e struttura dell'interno della Terra
    Description: JCR Journal
    Description: restricted
    Keywords: Seismic attenuation ; Seismic tomography ; Statistical seismology ; Subduction zone processes ; 04. Solid Earth::04.06. Seismology::04.06.07. Tomography and anisotropy ; 05. General::05.01. Computational geophysics::05.01.04. Statistical analysis
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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