Six‐Axis Ground Motion Measurements of Caldera Collapse at Kīlauea Volcano, Hawai'i—More Data, More Puzzles?

J Wassermann,I Johanson,F Bernauer,H Igel,B Shiro,F Guattari

doi:10.1029/2019gl085999

Abstract

AbstractNear‐field recordings of large earthquakes and volcano‐induced events using traditional seismological instrumentation often suffer from unaccounted effects of local tilt and saturation of signals. Recent hardware advances have led to the development of the blueSeis‐3A, a very broadband, highly sensitive rotational motion sensor. We installed this sensor in close proximity to permanently deployed classical instrumentation (i.e., translational seismometer, accelerometer, and tiltmeter) at the Hawaiian Volcano Observatory (USGS). There, we were able to record three ~Mw 5 earthquakes associated with large collapse events during the later phase of the 2018 Kīlauea summit eruption. Located less than 2 km from the origins of these sources, the combined six‐axis translational and rotational measurements revealed clear static rotations around all three coordinate axes. With these six component recordings, we have been able to reconstruct the complete time history of ground motion of a fixed point during an earthquake for the first time.

Highlights

The May to August 2018 eruption of Kīlauea volcano was exceptional in many respects, representing one of the largest eruptions of the volcano in over 200 years (Neal et al, 2019)
Recent hardware advances have led to the development of the blueSeis‐3A, a very broadband, highly sensitive rotational motion sensor. We installed this sensor in close proximity to permanently deployed classical instrumentation at the Hawaiian Volcano Observatory (USGS)
The co‐location of this instrument in the vault allowed for simultaneous recording and direct comparison of the blueSeis‐3A rotational measurements with translational and tilt data from the other instruments in the vault

Summary

Introduction

The May to August 2018 eruption of Kīlauea volcano was exceptional in many respects, representing one of the largest eruptions of the volcano in over 200 years (Neal et al, 2019). A series of recent papers (Bernauer et al, 2014; Donner et al, 2016; Igel et al, 2007; Wassermann et al, 2016) demonstrated how three component rotational combined with three component translational (i.e., six‐axis) measurements may help to improve our capability to invert for local (S‐wave) velocity, to localize events, and to estimate source mechanisms even in the case of sparse seismic station networks and local tilt effects.

Results

Conclusion