The locations of magma chambers at Mt. Etna, Italy, mapped by <i>b</i>‐values

Murru, Maura; Montuori, Caterina; Wyss, Max; Privitera, E.

doi:10.1029/1999gl900568

Cited by 151 publications

(99 citation statements)

References 15 publications

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“…This overall picture shows analogies with the pattern found by Murru et al (1999Murru et al ( , 2007 on a temporally different earthquake dataset (1999)(2000)(2001)(2002)(2003)(2004)(2005), highlighting two areas characterized by higher b values than other surrounding areas: (i) beneath the central craters and (ii) in the eastern flank, at a depth range of 5-7 km. Although the b values cannot be compared as absolute numbers because they were calculated from two different magnitude scales -M L in this study, M d in the Murru et al (2007) paper -the aforementioned spatial variations remain constant during time though the datasets cover contiguous time windows.…”

Section: Distributed Seismicitysupporting

confidence: 51%

When probabilistic seismic hazard climbs volcanoes: the Mt. Etna case, Italy – Part 1: Model components for sources parameterization

Azzaro

Barberi

D’Amico

et al. 2017

Nat. Hazards Earth Syst. Sci.

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Abstract. The volcanic region of Mt. Etna (Sicily, Italy) represents a perfect lab for testing innovative approaches to seismic hazard assessment. This is largely due to the long record of historical and recent observations of seismic and tectonic phenomena, the high quality of various geophysical monitoring and particularly the rapid geodynamics clearly demonstrate some seismotectonic processes. We present here the model components and the procedures adopted for defining seismic sources to be used in a new generation of probabilistic seismic hazard assessment (PSHA), the first results and maps of which are presented in a companion paper, . The sources include, with increasing complexity, seismic zones, individual faults and gridded point sources that are obtained by integrating geological field data with long and short earthquake datasets (the historical macroseismic catalogue, which covers about 3 centuries, and a highquality instrumental location database for the last decades). The analysis of the frequency-magnitude distribution identifies two main fault systems within the volcanic complex featuring different seismic rates that are controlled essentially by volcano-tectonic processes. We discuss the variability of the mean occurrence times of major earthquakes along the main Etnean faults by using an historical approach and a purely geologic method. We derive a magnitude-size scaling relationship specifically for this volcanic area, which has been implemented into a recently developed software toolFiSH (Pace et al., 2016) -that we use to calculate the characteristic magnitudes and the related mean recurrence times expected for each fault. Results suggest that for the Mt. Etna area, the traditional assumptions of uniform and Poissonian seismicity can be relaxed; a time-dependent fault-based modeling, joined with a 3-D imaging of volcano-tectonic sources depicted by the recent instrumental seismicity, can therefore be implemented in PSHA maps. They can be relevant for the retrofitting of the existing building stock and for driving risk reduction interventions. These analyses do not account for regional M > 6 seismogenic sources which dominate the hazard over long return times (≥ 500 years).

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Section: Distributed Seismicitysupporting

confidence: 51%

When probabilistic seismic hazard climbs volcanoes: the Mt. Etna case, Italy – Part 1: Model components for sources parameterization

Azzaro

Barberi

D’Amico

et al. 2017

Nat. Hazards Earth Syst. Sci.

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“…The observed lack of large-magnitude earthquakes in the MER is consistent with geodetic data that show that the majority of strain across the MER is accommodated aseismically (Hofstetter andBeyth, 2003 Bendick et al, 2006). Studies of seismically active magmatic systems show that M c and b-value can vary in space and time (e.g., Wiemer et al, 1998;Murru et al, 1999). The b-value obtained in our study is based on only 16 months of data from a 250 km ‫ן‬ 350 km area and may thus be biased by short-term spatial and temporal variations in the pattern of seismic activity.…”

Section: Discussionmentioning

confidence: 87%

Local Earthquake Magnitude Scale and Seismicity Rate for the Ethiopian Rift

Keir¹,

Stuart²,

Jackson³

et al. 2006

Bulletin of the Seismological Society of America

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A calibrated local earthquake magnitude scale is essential for quantitative analyses of seismicity. In Ethiopia, effective monitoring of earthquakes and resulting assessment of seismic hazard are especially important as regions with seismic and volcanic activity coincide with regions of economic significance and population growth. We have developed a local magnitude (M L ) scale for the northern Main Ethiopian rift (MER) using earthquake data collected during 2001-2003 on 122 three-component broadband seismic stations. Waveform data from 2139 local earthquakes were corrected for instrument response and convolved with the nominal Wood-Anderson torsion seismograph response appropriate for the original definition of local magnitude. The hypocentral distances considered are 5 to 800 km, with the best represented range from 5 to 150 km. A total of 30,908 maximum zero-to-peak amplitudes (A WA ) were incorporated into a direct linear inversion for individual earthquake local magnitudes (M L ), 244 station factors (C), and 2 linear distance-dependent factors (n, K) in the distance correction term, log (A o ), of the equation for local magnitude: M L ‫ס‬ log(A WA ) ‫מ‬ log(A o ) ‫ם‬ C. The resulting distance correction is given by ‫מ‬log(A o ) ‫ס‬ 1.196997log(r/17) ‫ם‬ 0.001066(r ‫מ‬ 17) ‫ם‬ 2, which implies that ground-motion attenuation is relatively high, consistent with ongoing magma intrusion and the presence of shallow magma reservoirs beneath the MER. Station corrections significantly reduce M L residuals and range between ‫24.0ע‬ M L units. The catalog of earthquakes is complete above M L ϳ2.1 and the annual cumulative seismicity rate follows the relation log N ‫ס‬ 4.5 ‫מ‬ 1.13 M L . Our results are critical for accurate routine quantitative analysis of past, current and, future seismicity in Ethiopia.

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“…Etna mainly on the basis of ground deformation (Bonaccorso et al 1994;Bonaccorso 1996) and seismic data (Murru et al 1999;Patanè et al 2003). In particular, Murru et al (1999) found evidence of at least two magma reservoirs. One has a radius less than 2 km and is located WSW of the summit at about 3 ± 2 km b.s.l.…”

Section: Shallow Magma Reservoirsmentioning

confidence: 99%