Mechanical and thermo-fluid behaviour during unrest at the Campi Flegrei caldera (Italy)

Orsi, G.; Petrazzuoli, S.M.; Wohletz, Kenneth H.

doi:10.1016/s0377-0273(99)00051-7

Cited by 53 publications

(36 citation statements)

References 36 publications

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“…2a; Dvorak and Mastrolorenzo 1991;De Natale et al 1995;Orsi et al 1999a). Several models have been proposed to explain the 1982-1984 bradyseism in the frame of magmatic input (Berrino et al 1984;De Natale and Pingue 1988;Dvorak and Berrino 1991;De Natale and Pingue 1993;Troise et al 1997) or the pressurization of a hydrothermal system (Orsi et al 1999b;Chiodini et al 2001;Gottsmann et al 2003;Battaglia et al 2006) or multiple sources (Gottsmann et al 2006). In the last decades, Campi Flegrei caldera has been undergoing moderate and localized uplifts (<5 cm, in the Solfatara crater area, characterized by a widespread hydrothermal activity; Fig.…”

Section: Geology Of Campi Flegrei Calderamentioning

confidence: 99%

Evaluating fracture patterns within a resurgent caldera: Campi Flegrei, Italy

Acocella

2010

Bull Volcanol

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Understanding deformation of active calderas allows their dynamics to be defined and their hazard mitigated. The Campi Flegrei resurgent caldera (Italy) is one of the most active and hazardous volcanoes in the world, characterized by post-collapse resurgence, eruptions, ground deformation, and seismicity. An original structural analysis provides an overview of the main fracture zones. NW-SE and NE-SW fractures (normal or transtensive faults and extensional fractures) predominate along the rim and within the caldera, suggesting a regional control, both during and after the collapses. While the NE-SW fractures are ubiquitous in the deposits of the last ∼37 ka, NW-SE fractures predominate in the last 4.5 ka, during resurgence. The most recently (<4.5 ka) strained area lies in the caldera center (Solfatara area), where the faults, with an overall ∼ENE-WSW extension direction, appear to be associated with the bending due to resurgence. Solfatara lies immediately to the east of the most uplifted part of the caldera (Pozzuoli area), where domes form and culminate both on the long-term (resurgence, accompanied by volcanic activity) and short-term deformation (1982)(1983)(1984) bradyseism, accompanied by seismic and hydrothermal activity). Similar volcano-tectonic behavior characterizes the short-and long-term uplifts, and only the intensity of the tectonic and volcanic activity varies, being related to varying amounts of uplift. Seismicity and hydrothermal manifestations occur during the bradyseisms, with moderate uplift, while surface faulting and eruptions occur during resurgence, with higher uplift. The features observed at Campi Flegrei are found at other major calderas, suggesting consistent behavior of large magmatic systems.

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Section: Geology Of Campi Flegrei Calderamentioning

confidence: 99%

Evaluating fracture patterns within a resurgent caldera: Campi Flegrei, Italy

Acocella

2010

Bull Volcanol

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“…The reconstruction of the thermal history of the Campi Flegrei magmatic system (Wohletz et al 1999) has permitted to estimate the present setting of the thermo-fluid dynamical system and to hypothesise its contribution to the evolution of the recent bradyseismic events (Orsi et al 1999b). The present state of the system results from a sequence of input of new magma batches from depth and extrusion through eruptions since at least 60 ka.…”

Section: Present Statementioning

confidence: 99%

“…The latter is separated from the magmatic system and likely confined in the caldera fill. Analyses of fluid-solid interaction (Orsi et al 1999b), based on the present state of the system Wohletz et al 1999;Di Maio et al 2000;Iuliano et al 2000), have also shown that lateral migration of fluids can be a component of the ductile deformation of the shallow crust during subsidence. The results of these analyses explain the absence of seismicity during subsidence and corroborate the hypothesis that the bradyseismic events are transient episodes in the long-term evolution of the thermal system (Orsi et al 1996;1999a).…”

Section: Present Statementioning

confidence: 99%

Volcanic hazard assessment at the restless Campi Flegrei caldera

2004

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Eruption forecasting and hazard assessments at the restless Campi Flegrei caldera, within the Neapolitan volcanic area, have been performed using stratigraphical, volcanological, structural and petrological data.On the basis of the reconstructed variation of eruption magnitude through time, we hypothesize that the most probable maximum expected event is a medium-magnitude explosive eruption, fed by trachytic magma. Such an eruption could likely occur in the north-eastern sector of the caldera floor that is under a tensile stress regime, when the ongoing deformation will generate mechanical failure of the rocks. A vent could open also in the western sector, at the intersection of two fault systems contemporaneously activated, as happened in the last eruption at Monte Nuovo. The eruption could likely be preceded by precursors apparent to the population, such as ground deformation, seismicity and increase in gas emissions. It will probably alternate between magmatic and phreatomagmatic phases with the generation of tephra fallout, and dilute and turbulent pyroclastic currents. During and/or after the eruption, the re-mobilization of ash by likely heavy rains, could probably generate mud flows.In order to perform a zoning of the territory in relation to the expected volcanic hazards, we have constructed a comprehensive hazard map. On this map are delimited (I) areas of variable probability of opening of a new vent, (II) areas which could be affected by variable load of fallout deposits, and (III) areas over which pyroclastic currents could flow. The areas in which a vent could likely open have been defined on the basis of the dynamics of the ongoing deformation of the caldera floor. To construct the fallout hazard map we have used the frequency of deposition of fallout beds thicker than 10 cm, the frequency of load on the ground by tephra fallout and the direction of dispersal axes of the deposits of the last 5 ka, and the limit load of collapse for the variable types of roof construction. The pyroclastic-current hazard map is based on the areal distribution and frequency of pyroclastic-current deposits of the last 5 ka.

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“…Mandel (1953), Terzaghi (1943)) or the phenomena involved in earthquakes (see e.g. Yang (1999) or in the bradyseism and in the related micro-earthquakes in the Phlegraean Fields -Campi Flegrei region (South Italy) (see dell'Isola a et al (1998) and references there cited, Casertano et al (1976), Orsi et al (1999)). …”

Section: Introductionmentioning

confidence: 99%