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Caldera Collapse Geometry Revealed by Near-field GPS Displacements at Kilauea Volcano in 2018
  • +2
  • Paul Segall,
  • Kyle Anderson,
  • Fabio Pulvirenti,
  • Taiyi Wang,
  • Ingrid A. Johanson
Paul Segall
Stanford University

Corresponding Author:[email protected]

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Kyle Anderson
United States Geological Survey
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Fabio Pulvirenti
Jet Propulsion Laboratory, California Institute of Technology
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Taiyi Wang
Stanford University
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Ingrid A. Johanson
U. S. Geological Survey
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Abstract

We employ near-field GPS data to determine the subsurface geometry of a collapsing caldera during the 2018 Kilauea eruption. Collapse occurred in 62 discrete events with “inflationary’ deformation external to the collapse similar to previous basaltic collapses. We employ GPS data from the collapsing block, and constraints on the magma chamber geometry from inversion of deflation prior to collapse. This provides an unparalleled opportunity to constrain the collapse geometry. Employing an axisymmetric finite element model, the co-collapse displacements are best explained by piston-like subsidence along a steep (~85 degree) normal ring-fault that may steepen with depth. Magma compressibility is 2-15 x 10 Pa, indicating bubble volume fractions from 1 to 7 % (lower if fault steepens with depth). Magma pressure increases during collapses are 1-3 MPa, depending on compressibility. A point source in a half-space fits the data well, but provides a biased representation of the source depth and process.