Influence of ring faulting in localizing surface deformation at subsiding calderas
KAUST DepartmentEarth Science and Engineering Program
Physical Sciences and Engineering (PSE) Division
KAUST Grant NumberBAS/1/1353-01-01
Embargo End Date2021-09-05
Permanent link to this recordhttp://hdl.handle.net/10754/656712
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AbstractCaldera unrest can lead to major volcanic eruptions. Analysis of subtle subsidence or inflation at calderas helps understanding of their subsurface volcanic processes and related hazards. Several subsiding calderas have shown similar patterns of ground deformation composed of broad subsidence affecting the entire volcanic edifice and stronger localized subsidence focused inside the caldera. Physical models of internal deformation sources used to explain these observations typically consist of two magma reservoirs at different depths in an elastic half-space. However, such models ignore important subsurface structures, such as ring faults, that may influence the deformation pattern. Here we use both analog subsidence experiments and boundary element modeling to study the three-dimensional geometry and kinematics of caldera subsidence processes, evolving from an initial downsag to a later collapse stage. We propose that broad subsidence is mainly caused by volume decrease within a single magma reservoir, whereas buried ring-fault activity localizes the deformation within the caldera. Omitting ring faulting in physical models of subsiding calderas and using multiple point/sill-like sources instead can result in erroneous estimates of magma reservoir depths and volume changes.
SponsorsWe thank Prof. Sigurdur Thoroddsen, Dr. Nadia Kouraytem, Dr. Andres A. Aguirre-Pablo, and Aditya Jetly in the High-Speed Fluids Imaging Laboratory at King Abdullah University of Science and Technology (KAUST) for providing camera equipment and laboratory facilities for our analog experiments. The granular material used in the analog experiments was provided by Dr. Daniele Trippanera (Roma Tre University, now at KAUST). We also thank Mehdi Nikkhoo for fruitfull discussions as well as Yosuke Aoki and one anonymous reviewer that helped to improve the quality of the manuscript. The research reported in this publication was supported by KAUST, award number BAS/1/1353-01-01.