The role of viscous magma mush spreading in volcanic flank motion at Kīlauea Volcano, Hawai‘i

Journal of Geophysical Research B: Solid Earth
By: , and 



Multiple mechanisms have been suggested to explain seaward motion of the south flank of Kīlauea Volcano, Hawai‘i. The consistency of flank motion during both waxing and waning magmatic activity at Kīlauea suggests that a continuously acting force, like gravity body force, plays a substantial role. Using finite element models, we test whether gravity is the principal driver of long-term motion of Kīlauea's flank. We compare our model results to geodetic data from Global Positioning System and interferometric synthetic aperture radar during a time period with few magmatic and tectonic events (2000-2003), when deformation of Kīlauea was dominated by summit subsidence and seaward motion of the south flank. We find that gravity-only models can reproduce the horizontal surface velocities if we incorporate a regional décollement fault and a deep, low-viscosity magma mush zone. To obtain quasi steady state horizontal surface velocities that explain the long-term seaward motion of the flank, we find that an additional weak zone is needed, which is an extensional rift zone above the magma mush. The spreading rate in our model is mainly controlled by the magma mush viscosity, while its density plays a less significant role. We find that a viscosity of 2.5 × 1017–2.5 × 1019 Pa s for the magma mush provides an acceptable fit to the observed horizontal surface deformation. Using high magma mush viscosities, such as 2.5 × 1019 Pa s, the deformation rates remain more steady state over longer time scales. These models explain a significant amount of the observed subsidence at Kīlauea's summit. Some of the remaining subsidence is probably a result of magma withdrawal from subsurface reservoirs.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title The role of viscous magma mush spreading in volcanic flank motion at Kīlauea Volcano, Hawai‘i
Series title Journal of Geophysical Research B: Solid Earth
DOI 10.1002/jgrb.50194
Volume 118
Issue 5
Year Published 2013
Language English
Publisher Wiley
Contributing office(s) Hawaiian Volcano Observatory, Volcano Science Center
Description 14 p.
Larger Work Type Article
Larger Work Subtype Journal Article
Larger Work Title Journal of Geophysical Research B: Solid Earth
First page 2474
Last page 2487
Country United States
State Hawai'i
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