Simultaneous inversion of deformation and gravity changes in a horizontally layered half-space: Evidences for magma intrusion during the 1982–1984 unrest at Campi Flegrei caldera (Italy)

Amoruso, Antonella; Crescentini, Luca; Berrino, Giovanna

doi:10.1016/j.epsl.2008.04.040

Cited by 72 publications

(103 citation statements)

References 24 publications

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“…Unrest events (bradyseism) have affected the area in the last 35 years (e.g., Barberi et al 1989); the last bradyseism episode occurred in the 1980s, resulting in a net 3.5 m uplift at Pozzuoli harbor De Natale et al 2006). According to geodetic data, the 1982-1984 unrest may have been related to shallow magma intrusion (Amoruso et al 2008), followed by upstreaming of magmatic CO 2 -rich gas and low-pressure accumulation of mixed magmatic and hydrothermal components Caliro et al 2007). The existence of magma reservoir(s) at a depth of *4-5 km was previously suggested on the basis of thermal (Wohletz et al 1999), magnetic , and seismological data (Ferrucci et al 1992).…”

Section: Introductionmentioning

confidence: 99%

Crystal fractionation, magma step ascent, and syn-eruptive mingling: the Averno 2 eruption (Phlegraean Fields, Italy)

Fourmentraux

Métrich

Bertagnini

et al. 2012

Contrib Mineral Petrol

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The 3.7 ka year-old Averno 2 eruption is one of the rare eruptions to have occurred in the northwest sector of the Phlegraean Fields caldera (PFc) over the past 5 ka. We focus here on the fallout deposits of the pyroclastic succession emplaced during this eruption. We present major and trace element data on the bulk pumices, along with major and volatile element data on clinopyroxene-hosted melt inclusions, in order to assess the conditions of storage, ascent, and eruption of the feeding trachytic magma. Crystal fractionation accounts for the evolution from trachyte to alkali-trachyte magmas; these were intimately mingled (at the micrometer scale) during the climactic phase of the eruption. The Averno 2 alkali trachyte represents one of the most evolved magmas erupted within the Phlegraean Fields area and belongs to the series of differentiated trachytic magmas erupted at different locations 5 ka ago. Melt inclusions record significant variations in H 2 O (from 0.4 to 5 wt%), S (from 0.01 to 0.06 wt%), Cl (from 0.75 up to 1 wt%), and F (from 0.20 to [0.50 wt%) during both magma crystallization and degassing. Unlike the eruptions occurring in the central part of the PFc, deep-derived input(s) of gas and/or magma are not required to explain the composition of melt inclusions and the mineralogy of Averno 2 pumices. Compositional data on bulk pumices, glassy matrices, and melt inclusions suggest that the Averno 2 eruption mainly resulted from successive extrusions of independent magma batches probably emplaced at depths of 2-4 km along regional fractures bordering the Neapolitan Yellow Tuff caldera.

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Section: Introductionmentioning

confidence: 99%

Crystal fractionation, magma step ascent, and syn-eruptive mingling: the Averno 2 eruption (Phlegraean Fields, Italy)

Fourmentraux

Métrich

Bertagnini

et al. 2012

Contrib Mineral Petrol

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“…Todesco and Berrino, 2005;Hurwitz et al, 2007;Hutnak et al, 2009;Todesco et al, 2010;Rouwet et al, 2014) from those related to magma movement towards the surface (e.g. Amoruso et al, 2008Amoruso et al, , 2014bWoo and Kilburn, 2010;Trasatti et al, 2011). Few deformation models account for significant complexities such as heterogeneities in key hydrological and mechanical properties of matrix and faults, which might influence both the path of ascending magma and the sub-surface circulation of hydrothermal fluids.…”

Section: Introductionmentioning

confidence: 99%

Numerical models for ground deformation and gravity changes during volcanic unrest: simulating the hydrothermal system dynamics of a restless caldera

et al. 2016

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Abstract. Ground deformation and gravity changes in restless calderas during periods of unrest can signal an impending eruption and thus must be correctly interpreted for hazard evaluation. It is critical to differentiate variation of geophysical observables related to volume and pressure changes induced by magma migration from shallow hydrothermal activity associated with hot fluids of magmatic origin rising from depth. In this paper we present a numerical model to evaluate the thermo-poroelastic response of the hydrothermal system in a caldera setting by simulating pore pressure and thermal expansion associated with deep injection of hot fluids (water and carbon dioxide). Hydrothermal fluid circulation is simulated using TOUGH2, a multicomponent multiphase simulator of fluid flows in porous media. Changes in pore pressure and temperature are then evaluated and fed into a thermo-poroelastic model (one-way coupling), which is based on a finite-difference numerical method designed for axi-symmetric problems in unbounded domains.Informed by constraints available for the Campi Flegrei caldera (Italy), a series of simulations assess the influence of fluid injection rates and mechanical properties on the hydrothermal system, uplift and gravity. Heterogeneities in hydrological and mechanical properties associated with the presence of ring faults are a key determinant of the fluid flow pattern and consequently the geophysical observables. Peaks (in absolute value) of uplift and gravity change profiles computed at the ground surface are located close to injection points (namely at the centre of the model and fault areas).Temporal evolution of the ground deformation indicates that the contribution of thermal effects to the total uplift is almost negligible with respect to the pore pressure contribution during the first years of the unrest, but increases in time and becomes dominant after a long period of the simulation. After a transient increase over the first years of unrest, gravity changes become negative and decrease monotonically towards a steady-state value.Since the physics of the investigated hydrothermal system is similar to any fluid-filled reservoir, such as oil fields or CO 2 reservoirs produced by sequestration, the generic formulation of the model will allow it to be employed in monitoring and interpretation of deformation and gravity data associated with other geophysical hazards that pose a risk to human activity.

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“…Battaglia et al (2006) provided a good fit to the 1980-1984 deformation pattern, which, during the uplift period, appeared to be due to a horizontal penny-shaped source with an average density close to that of the hydrothermal fluids, while the source that provided the best fit for the deflation period (1990)(1991)(1992)(1993)(1994)(1995) was a vertical spheroid with the same average density. According to the gravity changes, Amoruso et al (2008) also indicated that the deformation pattern that occurred during the 1982-1984 unrest was produced by a shallow penny-shaped magma intrusion, although they ruled out the hydrothermal fluid as the primary cause of the deformation. However, this last study did not model the deflation period following the 1982-1984 crisis (Amoruso et al 2008), which is fundamental to fully understand the rheology of the rock and the unrest dynamics.…”

Section: Introductionmentioning

confidence: 95%

“…According to the gravity changes, Amoruso et al (2008) also indicated that the deformation pattern that occurred during the 1982-1984 unrest was produced by a shallow penny-shaped magma intrusion, although they ruled out the hydrothermal fluid as the primary cause of the deformation. However, this last study did not model the deflation period following the 1982-1984 crisis (Amoruso et al 2008), which is fundamental to fully understand the rheology of the rock and the unrest dynamics. Lima et al (2009) interpreted the unrest at CFc as a consequence of aqueous fluid exolution during magma solidification at different timescales.…”

Section: Introductionmentioning

confidence: 95%

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Eruptive versus non-eruptive behaviour of large calderas: the example of Campi Flegrei caldera (southern Italy)

Carlino

Somma

2010

Bull Volcanol

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Caldera eruptions are among the most hazardous of natural phenomena. Many calderas around the world are active and are characterised by recurrent uplift and subsidence periods due to the dynamics of their magma reservoirs. These periods of unrest are, in some cases, accompanied by eruptions. At Campi Flegrei caldera (CFc), which is an area characterised by very high volcanic risk, the recurrence of this behaviour has stimulated the study of the rock rheology around the magma chamber, in order to estimate the likelihood of an eruption. This study considers different scenarios of shallow crustal behaviour, taking into account the earlier models of CFc ground deformation and caldera eruptions, and including recent geophysical investigations of the area. A semi-quantitative evaluation of the different factors that lead to magma storage or to its eruption (such as magma chamber size, wall-rock viscosity, temperature, and regional tectonic strain rate) is reported here for elastic and viscoelastic conditions. Considering the large magmatic sources of the CFc ignimbrite eruptions (400-2,000 km 3 ) and a wall-rock viscosity between 10 18 and 10 20 Pa s, the conditions for eruptive failure are difficult to attain. Smaller source dimensions (a few cubic kilometres) promote the condition for fracture (eruption) rather than for the flow of wall rock. We also analyse the influence of the regional extensional stress regime on magma storage and eruptions, and the thermal stress as a possible source of caldera uplift. The present study also emphasises the difficulty of distinguishing eruption and non-eruption scenarios at CFc, since an unambiguous model that accounts for the rock rheology, magma-source dimensions and locations and regional stress field influences is still lacking.

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Simultaneous inversion of deformation and gravity changes in a horizontally layered half-space: Evidences for magma intrusion during the 1982–1984 unrest at Campi Flegrei caldera (Italy)

Cited by 72 publications

References 24 publications

Crystal fractionation, magma step ascent, and syn-eruptive mingling: the Averno 2 eruption (Phlegraean Fields, Italy)

Crystal fractionation, magma step ascent, and syn-eruptive mingling: the Averno 2 eruption (Phlegraean Fields, Italy)

Numerical models for ground deformation and gravity changes during volcanic unrest: simulating the hydrothermal system dynamics of a restless caldera

Eruptive versus non-eruptive behaviour of large calderas: the example of Campi Flegrei caldera (southern Italy)

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