Please use this identifier to cite or link to this item: http://hdl.handle.net/2122/463
AuthorsTrasatti, E.* 
Giunchi, C.* 
Bonafede, M.* 
TitleStructural and rheological constraints on source depth and overpressure estimates at the Campi Flegrei caldera, Italy
Issue Date2005
Series/Report no.144 (2005)
URIhttp://hdl.handle.net/2122/463
Keywordsfinite element modelling
Campi Flegrei
surface deformation
plasticity
rheological layering
overpressure source
Subject Classification04. Solid Earth::04.03. Geodesy::04.03.01. Crustal deformations 
AbstractThe 1982-84 unrest episode at Campi Flegrei (CF) caldera, Italy, was characterized by huge deformation (more than 1.5 m uplift) concentrated inside the caldera. According to point source isotropic models in homogeneous elastic and visco-elastic half-spaces, the source depth is very shallow (about 3 km). If the source radius is about 1 km this implies that magma is at a depth of 2 km depth. However, several independent observations show that the top of the magma chamber at CF must be deeper than 4 km. This paper investigates how the inferred source depth increases when rigidity heterogeneities (obtained through seismic tomography at CF) are considered and when the long-term deformation takes place under drained conditions. Finite element models indicate that overpressure needed at the source to reproduce the 1.5 m maximum uplift is however beyond typical rock strength values. This evidence, together with the high thermal anomalies, the presence of fluids and the low cohesion of tuffs filling the caldera, suggests the use of elastoplastic constitutive laws. For elastoplastic behavior, the same deformation is obtained using a deeper source (with center at 5 km depth) and a lower overpressure (than required by elastic models). The plastic deformation concentrates both at the source boundaries and above the source, where seismic activity has been recorded. These results indicate that the rheological properties of the shallow crust of CF have important implications for hazard estimate during unrest episodes.
Appears in Collections:Manuscripts
Papers Published / Papers in press

Files in This Item:
File Description SizeFormat 
sdarticle.pdf322.76 kBAdobe PDFView/Open    Request a copy
Show full item record

Page view(s)

129
checked on Apr 24, 2017

Download(s)

23
checked on Apr 24, 2017

Google ScholarTM

Check