Gottsmann, Joachim; Camacho, Antonio G.; Martí Molist, Joan; Wooller, Luke K.; Fernández Torres, José; García García, Alicia; Rymer, Hazel
We present a new local Bouguer anomaly map of the Central Volcanic Complex (CVC) of Tenerife, Spain, constructed from the amalgamation of 323 new high precision gravity measurements with existing gravity data from 361 observations. The new anomaly map images the high-density core of the CVC and the pronounced gravity low centred in the Las Cañadas caldera in greater detail than previously available. Mathematical construction of a sub-surface model from the local anomaly data, employing a 3D inversion based on “growing” the sub-surface density distribution via the aggregation of cells, enables mapping of the shallow structure beneath the complex, giving...
Gottsmann, Joachim; Wooller, Luke K.; Martí Molist, Joan; Fernández Torres, José; Camacho, Antonio G.; González Méndez, Pablo José; García García, Alicia; Rymer, Hazel
Geophysical signals accompanying the reactivation of
a volcano after a period of quiescence must be evaluated as
potential precursors to impending eruption. Here we report
on the reactivation of the central volcanic complex of
Tenerife, Spain, in spring 2004 and present gravity change
maps constructed by time-lapse microgravity measurements
taken between May 2004 and July 2005. The gravity
changes indicate that the recent reactivation after almost a
century of inactivity was accompanied by a sub-surface
mass addition, yet we did not detect widespread surface
deformation. We find that the causative source was evolving
in space and time and infer fluid migration at depth as
the most likely cause for mass increase. Our...
(3400688 bytes; application/pdf) - 17-jul-2018
Fernández Torres, José; Tizzani, P.; Manzo, M.; Borgia, A.; González Méndez, Pablo José; Martí Molist, Joan; Camacho, Antonio G.; Casu, F.; Berardino, P.; Prieto, Juan Francisco; Lanari, R.; Pepe, A.
We study the state of deformation of Tenerife (Canary Islands) using Differential Synthetic Aperture Radar Interferometry (DInSAR). We apply the Small BAseline Subset (SBAS) DInSAR algorithm to radar images acquired from 1992 to 2005 by the ERS sensors to determine the deformation rate distribution and the time series for the coherent pixels identified in the island. Our analysis reveals that the summit area of the volcanic edifice is characterized by a rather continuous subsidence extending well beyond Las Cañadas caldera rim and corresponding to the dense core of the island. These results, coupled with GPS ones, structural and geological information...
(445232 bytes; application/pdf) - 17-jul-2018
Folch, A.; Fernández Torres, José; Rundle, J. B.; Martí Molist, Joan
We obtain and compare analytical and numerical solutions for ground displacement caused by an overpressurized magma chamber placed in a linear viscoelastic medium composed of a layer over a half-space. Different parameters such as size, depth and shape of the chamber, crustal rheology and topography are considered and discussed. Numerical solutions for an axisymmetric extended source are computed using a finite element method (FEM). Analytical solutions for a point source are obtained using the dislocation theory and the propagator matrix technique. In both cases, the elastic solutions are used together with the correspondence principle of linear viscoelasticity to obtain the...