Detecting pre-eruptive magmatic processes of the 2018 eruption at Kilauea, Hawaii volcano with ambient noise interferometry

Kuan-Fu Feng,Yih-Min Wu,Hsin-Hua Huang

doi:10.1186/s40623-020-01199-x

Abstract

A sequence of eruptions in the lower East Rift Zone (LERZ) of the Kilauea, Hawaii volcano commenced in early May 2018 and caused serious damage and residential evacuation. The post-eruption drainage and collapses of the summit lava lake and caldera suggest a well-connected magmatic plumbing system along the rift zone. How and when the pre-eruptive magmatic processes in such connecting system occurred are, however, still unclear. For that, we apply ambient noise interferometry with seismic data from January 2017 to June 2018 from 12 broadband seismometers to investigate spatiotemporal seismic velocity changes (dv/v) of the upper crust in the Kilauea area. The dv/v variations in three frequency bands (0.3–0.6 Hz, 0.6–0.9 Hz, and 0.9–2.0 Hz) show distinct responses to strong earthquake ground shaking and deep magmatic intrusion processes. Earthquake-induced dv/v drops mainly in the higher two frequency bands imply shallow mechanical changes within the uppermost 1 km of the crust. In contrast, the magma-related dv/v changes can be characterized into three periods of activity: from the December 2017 to March 15, 2018, a dv/v excursion only seen in the lowest frequency band indicates the magmatic intrusion processes taking place at the depth range of 1–4 km, consistent with the proposed depth of the magma reservoir-dike system in the rift zone. The spatial dv/v distribution suggests that the magma may intrude to the deeper summit magma reservoir and in the upper East Rift Zone (UERZ) at this time. From March 15 to April 17 in 2018, the summit inflation recorded by tiltmeters causes the dv/v increases in the higher two frequency bands. After April 17 to the eruption, the accumulating damage of the edifice together with the stronger intrusion activity in the UERZ result in dv/v decreases in all three frequency bands around the summit and UERZ areas. Our observations highlight that the ambient noise interferometry analysis provides an opportunity to image and understand the pre-eruptive processes of reservoir-dike magma system and could be a useful supplement to current volcanic monitoring systems.

Highlights

The lower East Rift Zone eruption of the Kilauea volcano The 2018 eruption of the Kilauea volcano began in early May and created a series of new fissures in the lower East Rift Zone (LERZ, Fig. 1)
Background of Kilauea volcano The Kilauea volcanic area consists of a main summit and two rift zones, the East Rift Zone (ERZ) and the Southwest Rift Zone (SWRZ)
From March 15 to April 17, 2018, the intrusion process reached the shallow magma reservoir and caused sensible summit inflation recorded by tiltmeters and increases in dv/v around the summit

Summary

Introduction

The lower East Rift Zone eruption of the Kilauea volcano The 2018 eruption of the Kilauea volcano began in early May and created a series of new fissures in the lower East Rift Zone (LERZ, Fig. 1). The pioneer study (Brenguier et al 2008) at volcano Piton de la Fournaise (PdF) found consistent decreases in seismic velocity a few weeks before eruptions over several cycles from 1999 to 2000 and suggested that precursory velocity decreases are caused by the inflation of volcanic edifice These inflation-related velocity decreases prior to eruptions have been observed in later studies at PdF (Duputel et al 2009; Obermann et al 2013a) and other volcanoes (Mordret et al 2010; Bennington et al 2015, 2018; MachaccaPuma et al 2019); velocity increases related to pre-eruptive inflation have been found at volcanoes as Miyakejima volcano (Anggono et al 2012), Merapi volcano (Budi-Santoso and Lesage 2016), and Kilauea volcano (Donaldson et al 2017). In contrast to the relatively inactive northern flank, the southern flank displaces seaward on a north-dipping basal decollement at a depth of approximately 7–9 km owing to the effects of magma injection into the rift zones and the topographic load of the island (Dieterich 1988; Denlinger and Okubo 1995; Dieterich and Cayol 2003; Heliker et al 2003; Poland et al 2017)

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Results

Conclusion