Caldera collapse geometry revealed by near‐field GPS displacements at Kīlauea Volcano in 2018

Geophysical Research Letters
By: , and 

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Abstract

We employ near‐field GPS data to determine the subsurface geometry of a collapsing caldera during the 2018 Kīlauea eruption. Collapse occurred in 62 discrete events, with “inflationary” deformation external to the collapse, similar to previous basaltic collapses. We take advantage of GPS data from the collapsing block and independent constraints on the magma chamber geometry from inversion of deflation prior to collapse onset. 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 high angle (85°) normal ring fault that may steepen to vertical with depth. Reservoir magma has compressibility of 2→15 × 10−10 Pa−1, indicating bubble volume fractions from 1% to 7% (lower if fault steepens with depth). Magma pressure increases during collapses are 1 to 3 MPa, depending on compressibility. Depressurization of a triaxial point source in a homogeneous half‐space fits the data well but provides a biased representation of the source depth and process.

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Publication type Article
Publication Subtype Journal Article
Title Caldera collapse geometry revealed by near‐field GPS displacements at Kilauea Volcano in 2018
Series title Geophysical Research Letters
DOI 10.1029/2020GL088867
Volume 47
Issue 15
Year Published 2020
Language English
Publisher American Geophysical Union
Contributing office(s) Volcano Science Center
Description e2020GL088867, 8 p.
Country United States
State Hawaii
Other Geospatial Kilauea Volcano
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