G. De Natale et al., Internal stress field at Mount Vesuvius: A model for background seismicityat a central volcano, J GEO R-SOL, 105(B7), 2000, pp. 16207-16214
We propose a model to explain the background seismicity occurring at Somma-
Vesuvius in its present, mostly quiescent period. A finite element procedur
e has been used to simulate the stress field due to gravitational body forc
es in an axisymmetric volcano characterized by a central high-rigidity anom
aly. Results emphasize the important effect of axial high-rigidity, which c
oncentrates at its borders stresses resulting; from the gravitational load
of the volcanic edifice, as well as external (regional) stresses. The joint
effect of the gravitational loading: and of the presence of the anomaly pr
oduces stresses very close to or above the critical rupture threshold. The
observed spatial concentrations of seismicity and moment release correlate
well with peaks of computed maximum shear stress. Seismicity is then interp
reted as due to small stress perturbations concentrated around the high-rig
idity core and added to a sa;stem already close to the failure threshold. T
his model call explain the widely observed occurrence of background seismic
ity at. central volcanoes worldwide.