Repeating caldera collapse events constrain fault friction at the kilometer scale

Proceedings of the National Academy of Sciences
By:  and 



Fault friction is central to understanding earthquakes, yet laboratory rock mechanics experiments are restricted to, at most, meter scale. Questions thus remain as to the applicability of measured frictional properties to faulting in situ. In particular, the slip-weakening distance dcdc strongly influences precursory slip during earthquake nucleation, but scales with fault roughness and is challenging to extrapolate to nature. The 2018 eruption of K̄ılauea volcano, Hawaii, caused 62 repeatable collapse events in which the summit caldera dropped several meters, accompanied by MWMW 4.7 to 5.4 very long period (VLP) earthquakes. Collapses were exceptionally well recorded by global positioning system (GPS) and tilt instruments and represent unique natural kilometer-scale friction experiments. We model a piston collapsing into a magma reservoir. Pressure at the piston base and shear stress on its margin, governed by rate and state friction, balance its weight. Downward motion of the piston compresses the underlying magma, driving flow to the eruption. Monte Carlo estimation of unknowns validates laboratory friction parameters at the kilometer scale, including the magnitude of steady-state velocity weakening. The absence of accelerating precollapse deformation constrains dcdc to be 10≤10 mm, potentially much less. These results support the use of laboratory friction laws and parameters for modeling earthquakes. We identify initial conditions and material and magma-system parameters that lead to episodic caldera collapse, revealing that small differences in eruptive vent elevation can lead to major differences in eruption volume and duration. Most historical basaltic caldera collapses were, at least partly, episodic, implying that the conditions for stick–slip derived here are commonly met in nature.

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Publication type Article
Publication Subtype Journal Article
Title Repeating caldera collapse events constrain fault friction at the kilometer scale
Series title Proceedings of the National Academy of Sciences
DOI 10.1073/pnas.2101469118
Volume 118
Issue 30
Year Published 2021
Language English
Publisher Proceedings of the National Academy of Sciences of the United States of America
Contributing office(s) Volcano Science Center
Description e2101469118, 7 p.
Country United States
State Hawaii
Other Geospatial Kilauea volcano
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