Determining the Stress Field in Active Volcanoes Using Focal Mechanisms

Massa, Bruno; D’Auria, Luca; Cristiano, Elena; Matteo, Ada De

doi:10.3389/feart.2016.00103

Cited by 8 publications

(11 citation statements)

References 81 publications

(137 reference statements)

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“…We used the FPFIT algorithm (Reasenberg & Oppenheimer, 1985) with rays traced through the 3D velocity model by Alparone et al As known, in volcanic environments the analysis of the stress field represents a valuable approach to infer the volcano dynamics (Costa & Marti, 2016;Gudmundsson, Acocella, & Vinciguerra, 2009;Hardebeck & Michael, 2006;Massa, D'Auria, Cristiano, & De Matteo, 2016;Plateaux, Bèthoux, Bergerat, & Lèpinay, 2014;Wyss, Habermann, & Bodin, 1992). Indeed, the stress changes play a key role in driving magmas and/or fluids migration within the shallow crust.…”

Section: D Fo C Al Mechanis M and S Tre Ss Tensor Analys Ismentioning

confidence: 99%

“…Indeed, the stress changes play a key role in driving magmas and/or fluids migration within the shallow crust. At the same time, injection of fluids can be responsible for local variations of the stress field, triggering tectonic earthquakes associated with major variations in the dynamics of volcanic eruptions and behaviour of hydrothermal phenomena (Massa et al, 2016).…”

Section: D Fo C Al Mechanis M and S Tre Ss Tensor Analys Ismentioning

confidence: 99%

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Seismological constraints on the 2018 Mt. Etna (Italy) flank eruption and implications for the flank dynamics of the volcano

et al. 2020

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3D earthquake locations, focal mechanisms and stress tensor distribution in a 16‐month interval covering the 2018 Mt. Etna flank eruption, enabled us to investigate the relationship between magma intrusion and structural response of the volcano and shed light on the dynamic processes affecting the instability of Mt. Etna. The magma intrusion likely caused tension in the flanks of the volcano, leading to significant ground deformation and redistribution of stress on the neighbouring faults at the edge of Mt. Etna's unstable sector, encouraging the ESE sliding of the eastern flank of the volcano. Accordingly, FPSs of the post‐eruptive events show strike slip faulting mechanisms, under a stress regime characterized by a maximum compressive σ1, NE‐SW oriented. In this perspective, any flank eruption could temporarily enhance the sliding process of both the southern and eastern flanks of the volcano.

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Section: D Fo C Al Mechanis M and S Tre Ss Tensor Analys Ismentioning

confidence: 99%

Section: D Fo C Al Mechanis M and S Tre Ss Tensor Analys Ismentioning

confidence: 99%

Seismological constraints on the 2018 Mt. Etna (Italy) flank eruption and implications for the flank dynamics of the volcano

et al. 2020

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“…However, the stress in deep rocks cannot be easily measured, therefore it is usually unknown. We can only investigate the stress conditions through geophysical methods, e.g., we can retrieve the orientation of the stress tensor through the inversion of focal mechanisms of earthquakes (D'Auria et al, 2015a;Massa et al, 2016). Conversely, the ground deformation, that is considered as an indicator of stress in the rock, can be measured quite easily through various techniques.…”

Section: Role Of Magma and Rock Propertiesmentioning

confidence: 99%

A Physical Model of Sill Expansion to Explain the Dynamics of Unrest at Calderas with Application to Campi Flegrei

2017

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Many calderas show remarkable unrest, which often does not culminate in eruptions (non-eruptive unrest). In this context the interpretation of the geophysical data collected by the monitoring networks is difficult. When the unrest is eruptive, a vent opening process occurs, which leads to an eruption. In calderas, vent locations typically are scattered over a large area and monogenic cones form. The resulting pattern is characterized by a wide dispersion of eruptive vents, therefore, the location of the future vent is not easily predictable. We propose an interpretation of the deformation associated to unrest and vent pattern commonly observed at calderas, based on a physical model that simulates the intrusion and the expansion of a sill. The model can explain both the uplift and any subsequent subsidence through a single process. Considering that the stress mainly controls the vent opening process, we try to gain insight on the vent opening in calderas through the study of the stress field produced by the intrusion of an expanding sill. We find that the tensile stress in the rock above the sill is concentrated at the sill edge in a ring-shaped area with radius depending on the physical properties of magma and rock, the feeding rate and the magma cooling rate. This stress field is consistent with widely dispersed eruptive vents and monogenic cone formation, which are often observed in the calderas. However, considering the mechanical properties of the elastic plate and the rheology of magma, we show that remarkable deformations may be associated with low values of stress in the rock at the top of the intrusion, thereby resulting in non-eruptive unrest. Moreover, we have found that, under the assumption of isothermal conditions, the stress values decrease over time during the intrusion process. This result may explain why the long-term unrest, in general, do not culminate in an eruption. The proposed approach concerns a general process and is applicable to many calderas. In particular, we simulate the vertical displacement as occurred in the centre of Campi Flegrei caldera during the last decades, and we obtain good agreement with the data of a leveling benchmark near the center of the caldera.

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“…where σ 1 (Pa) and σ 3 (Pa) are the maximum and minimum compressive stresses, respectively, β is an dimensional parameter related to the type of faulting (3.0, 1.2, and 0.75 for thrust, strike-slip, and normal faulting, respectively), ρ (kg m −3 ) is the density of the material, g (m s −2 ) is the acceleration of gravity, z (m) is the depth, and λ is the a dimensional pore fluid factor. According to both the focal mechanism study performed by Massa et al (2016) and the results of our THD analysis, the prevailing faulting regime in LVC is transcurrent/extensional, so as representative value of the rheological brittle regime β we used 1.2. We assumed a value of λ = 0.36 that generally characterizes the crust at least down to depths of 12 km (Ranalli & Murphy, 1987;Zoback & Townend, 2001).…”

Section: Rheological Implicationmentioning

confidence: 99%

“…According to both the focal mechanism study performed by Massa et al. (2016) and the results of our THD analysis, the prevailing faulting regime in LVC is transcurrent/extensional, so as representative value of the rheological brittle regime β we used 1.2. We assumed a value of λ = 0.36 that generally characterizes the crust at least down to depths of 12 km (Ranalli & Murphy, 1987; Zoback & Townend, 2001).…”

Section: Rheological Implicationmentioning

confidence: 99%

A Novel Multidisciplinary Approach for the Thermo‐Rheological Study of Volcanic Areas: The Case Study of Long Valley Caldera

et al. 2021

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The Long Valley caldera formed 0.760 Ma ago, as a result of a paroxysmal Bishop Tuff eruption. This event released 650-700 km 3 of gas-rich rhyolitic magma and drove the caldera collapse (Bailey, 1989; Carle, 1988; Hildreth & Wilson, 2007). Nowadays, the caldera has roughly an elliptical shape (∼17 km by 31 km) and hosts a magmatic-hydrothermal system which manifests itself at surface as hot springs and fumaroles. Geothermal facilities near the Casa Diablo locality supply 40 MW e from three binary power plants, exploiting ∼850 kg s −1 of 160-180°C water that circulates within the volcanic sediments, having depths spanning from 200 m to 350 m (Campbell, 2000). Since geothermal exploration began in 1960s the understanding of the geothermal system has continuously improved. Moreover, after the occurrence of the May 1980 earthquake swarm (D. P. Hill et al., 2017) many geological, geochemical, and geophysical studies focused on this area. The earthquakes were linked to a ∼0.25 m uplift of the old resurgent dome, located in the central part of the caldera (Battaglia et al., 1999; Tizzani et al., 2007, 2009). The seismic swarms and the inflation of the resurgent dome continue to date. Nowadays its center is ∼0.80 m higher. The seismic activity is associated with changes in discharge rates of hot springs and fumaroles in the southern and eastern sectors of the caldera, as well as with increased CO 2 emissions around Mammoth Mt. (at the southwestern border of the present-day caldera rim; Rogie et al., 2001; Sorey & Clark, 1981). These critical events leading to the creation of a multi-parameter monitoring network (managed by USGS), which in turn delivered the data through periodic public reports and monographies (e.g.

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Determining the Stress Field in Active Volcanoes Using Focal Mechanisms

Cited by 8 publications

References 81 publications

Seismological constraints on the 2018 Mt. Etna (Italy) flank eruption and implications for the flank dynamics of the volcano

Seismological constraints on the 2018 Mt. Etna (Italy) flank eruption and implications for the flank dynamics of the volcano

A Physical Model of Sill Expansion to Explain the Dynamics of Unrest at Calderas with Application to Campi Flegrei

A Novel Multidisciplinary Approach for the Thermo‐Rheological Study of Volcanic Areas: The Case Study of Long Valley Caldera

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