From deformation field analysis, we solve the boundary conditions common to the solid mechanics and the magma flux problems: internal structures geometry (“plumbing system”), pressure, stress and volume variations. The study also allows a better appraisal of monitoring measurements, thus helps hazard mitigation.
We focus our study on Mt. Merapi, Java, Indonesia, a Decade Volcano with a quasi continuous activity: dome growth, explosions and pyroclastic flows. Deformation field measurement come from GPS network and multi-component continuous stations (tiltmeters and extensometers). Data are always validated by compensation to determine uncertainties. For modeling, we use three-dimensional elasto-static boundary elements [Cayol & Cornet, 1997] including topography, fractures and complex geometry sources. Inversion processes are used to estimate parameter evolution and model probability from observations.
- Combination of high-precision tilt, displacements and topography constrains the modeling
- Evidence for a deep magma chamber at Merapi
- Evidence for fracture existence and their implications on the summit deformation field
- Compatibility of displacement observations and multi-phase seismic events: summit deformation field is controlled by magma flux
- Apparent elastic behaviour, but Young’s modulus less than 1 GPa (possibly linear visco-elastic reality)
- Mass balance must include rock avalanches
- Identify potential rock slope problems
Cayol, V., and F.H. Cornet, 3D mixed boundary elements for elastostatic deformation field analysis, Int. J. Rock Mech. Min. Sci., 34, 275–287, 1997.
See also Beauducel , Beauducel and Cornet , Beauducel et al. .