The large-scale surface uplift in the Altiplano-Puna region of Bolivia: A parametric study of source characteristics and crustal rheology using finite element analysis
Hickey, J; Gottsmann, J; del Potro, R
Date: 1 March 2013
Article
Journal
Geochemistry, Geophysics, Geosystems
Publisher
American Geophysical Union (AGU)
Publisher DOI
Abstract
This paper focuses on the driving mechanism behind a 70 km wide region of ground uplift centered on
Uturuncu volcano, in the Altiplano-Puna region of southern Bolivia. We present a series of forward models
using finite element analysis to simultaneously test for first-order parameters that help constrain a viable
model for the ...
This paper focuses on the driving mechanism behind a 70 km wide region of ground uplift centered on
Uturuncu volcano, in the Altiplano-Puna region of southern Bolivia. We present a series of forward models
using finite element analysis to simultaneously test for first-order parameters that help constrain a viable
model for the observed maximum line of sight uplift rate of 1–2 cm/yr between 1992 and 2006. Stresses
from pressure sources with finite geometries are solved numerically, accounting for both homogeneous
and heterogeneous mechanical rock properties in elastic and viscoelastic rheologies. Crustal heterogeneity
is constrained by seismic velocity data that indicate the presence of a large low-velocity zone, the AltiplanoPuna
magma body, at depths of ~17 km below the surface. A viscoelastic rheology is employed to account
for time-dependent deformation and an inelastic crust. Comparing homogeneous and heterogeneous
models demonstrates the significant impact of a mechanically weak, source-depth layer, which alters
surface displacement patterns by buffering subsurface deformation. Elastic model results guide the source
parameters tested in the viscoelastic models and demonstrate a range of possible causative source
geometries. Our preferred model suggests that pressurization of a magma source extending upward from
the Altiplano-Puna magma body is causing the observed surface uplift and alludes to a continued increase
in this pressure to explain both the spatial and temporal patterns. We also demonstrate how a pressure-time
function plays a first-order role in explaining the observed temporal deformation pattern
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