The intrusion of magma into Kīlauea's lower East Rift Zone in May 2018 led to the largest eruption along this segment of the volcano in over 200 years. As magma drained from the rift zone, leading to the collapse of Pu'u ‘Ō‘ō, pressure at the summit initially remained elevated and dropped at a slower rate compared to historical intrusion events. The anomalously long timescale of summit deflation suggests that the dike was fed from multiple sources. Here we show that dikes can serve as “dipsticks” of magma reservoirs and that the co‐evolution of dike growth and reservoir deflation constrains key magma transport parameters. Using coupled dike‐chamber models constrained by ground deformation and seismicity, we test four configurations of magma plumbing in order to illuminate which reservoirs and transport pathways were activated during the intrusion phase (30 April to 3 May) of the 2018 event. Slow summit deflation relative to the rate of dike propagation is best explained by a model in which the dike initiates from a compressible magma reservoir in the East Rift Zone, which then drains magma upstream from the Halema'uma'u reservoir through a shallow transport system. We use a Bayesian Markov chain Monte Carlo (MCMC) approach to estimate storage parameters for both reservoirs as well as the effective conductivity of the shallow magma transport system in the East Rift Zone, finding good agreement with independent estimates. Our results suggest that the rupture of reservoirs from within the East Rift Zone presents a unique hazard at Kīlauea.
The 2018 Kīlauea eruption was a complex event that included deformation and eruption at the summit and along the East Rift Zone. We use ambient seismic noise interferometry to measure time‐lapse changes in seismic velocity of the volcanic edifice prior to the lower East Rift Zone eruption. Our results show that seismic velocities increase in relation to gradual inflation of the edifice between 1 March and 20 April. In the 10 days prior to the 3rd of May eruption onset, a rapid seismic velocity decrease occurs even though the summit is still inflating. We confirm that intereruptive velocity change is correlated with surface deformation, while the velocity decrease prior to eruption is likely due to accumulating damage induced by the pressure exerted by the magma reservoir on the edifice. The accumulating damage and subsequent decrease in bulk edifice strength may have facilitated increased transport of magma from the summit reservoir to the Middle East Rift Zone.
more » « less- NSF-PAR ID:
- 10458664
- Publisher / Repository:
- DOI PREFIX: 10.1029
- Date Published:
- Journal Name:
- Geophysical Research Letters
- Volume:
- 46
- Issue:
- 7
- ISSN:
- 0094-8276
- Page Range / eLocation ID:
- p. 3734-3744
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract -
null (Ed.)The first eruption at Kīlauea’s summit in 25 years began on March 19, 2008, and persisted for 10 years. The onset of the eruption marked the first explosive activity at the summit since 1924, forming the new “Overlook crater” (as the 2008 summit eruption crater has been informally named) within the existing crater of Halemaʻumaʻu. The first year consisted of sporadic lava activity deep within the Overlook crater. Occasional small explosions deposited spatter and small wall-rock lithic pieces around the Halemaʻumaʻu rim. After a month-long pause at the end of 2008, deep sporadic lava lake activity returned in 2009. Continuous lava lake activity began in February 2010. The lake rose significantly in late 2010 and early 2011, before subsequently draining briefly in March 2011. This disruption of the summit eruption was triggered by eruptive activity on the East Rift Zone. Rising lake levels through 2012 established a more stable, larger lake in 2013, with continued enlargement over the subsequent 5 years. Lava reached the Overlook crater rim and overflowed on the Halemaʻumaʻu floor in brief episodes in 2015, 2016, and 2018, but the lake level was more commonly 20–60 meters below the rim during 2014–18. The lake was approximately 280×200 meters (~42,000 square meters) by early 2018 and formed one of the two largest lava lakes on Earth. A new eruption began in the lower East Rift Zone on May 3, 2018, causing magma to drain from the summit reservoir complex. The lava in Halemaʻumaʻu had drained below the crater floor by May 10, followed by collapse of the Overlook and Halemaʻumaʻu craters. The collapse region expanded as much of the broader summit caldera floor subsided incrementally during June and July. By early August 2018, the collapse sequence had ended, and the summit was quiet. The historic changes in May–August 2018 brought a dramatic end to the decade of sustained activity at Kīlauea’s summit. The unique accessibility of the 2008–18 lava lake provided new observations of lava lake behavior and open-vent basaltic outgassing. Data indicated that explosions were triggered by rockfalls from the crater walls, that the lake consisted of a low-density foamy lava, that cycles of gas pistoning were rooted at shallow depths in the lake, and that lake level fluctuations were closely tied to the pressure of the summit magma reservoir. Lava chemistry added further support for an efficient hydraulic connection between the summit and East Rift Zone. Notwithstanding the benefits to scientific understanding, the eruption presented a persistent hazard of volcanic air pollution (vog) that commonly extended far from Kīlauea’s summit.more » « less
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Abstract We examine the spatiotemporal variations in seismic parameters corresponding to the 2018 Kīlauea eruption. We find that the summit area had mainly strike‐slip focal solutions prior to the eruption, whereas normal‐faulting was the predominant feature during the eruption, partially due to the collapse events. In contrast, the majority of the earthquakes in the central south flank had normal‐faulting solutions before December 2017, in agreement with the normal‐faulting of the Hilina Fault System, while there are more reverse solutions during the eruption. We also observe temporal variations in the estimated in situ
ratios corresponding to the eruption, with increases in the summit and decreases in the East Rift Zone. The sustained low ratios below 4 km depth under the summit caldera may suggest persistent ascent of volatiles from the mantle. The low values in the East Rift Zone are probably associated with increased degassing. -
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Abstract Recent multi‐channel seismic studies of fast spreading and hot‐spot influenced mid‐ocean ridges reveal magma bodies located beneath the mid‐crustal Axial Magma Lens (AML), embedded within the underlying crustal mush zone. We here present new seismic images from the Juan de Fuca Ridge that show reflections interpreted to be from vertically stacked magma lenses in a number of locations beneath this intermediate‐spreading ridge. The brightest reflections are beneath Northern Symmetric segment, from ∼46°42′‐52′N and Split Seamount, where a small magma body at local Moho depths is also detected, inferred to be a source reservoir for the stacked magma lenses in the crust above. The imaged magma bodies are sub‐horizontal, extend continuously for along‐axis lengths of ∼1–8 km, with the shallowest located at depths of ∼100–1,200 m below the AML, and are similar to sub‐AML bodies found at the East Pacific Rise. At both ridges, stacked sill‐like lenses are detected beneath only a small fraction of the ridge length examined and are inferred to mark local sites of higher melt flux and active replenishment from depth. The imaged magma lenses are focused in the upper part of the lower crust, which coincides with the most melt rich part of the crystal mush zone detected in other geophysical studies and where sub‐vertical fabrics are observed in geologic exposures of oceanic crust. We infer that the multi‐level magma accumulations are ephemeral and may result from porous flow and mush compaction, and that they can be tapped and drained during dike intrusion and eruption events.
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Abstract Very‐long‐period (VLP) volcano seismicity often encodes subsurface magma movement, and thus provides insight into subsurface magma transport processes. We develop a fully automated signal processing workflow using wavelet transforms to detect and assess period, decay rate, and ground motions of resonant VLP signals. We then generate a VLP catalog over the 2008–2018 open‐vent summit eruption of Kīlauea Volcano containing thousands of events. Two types of magma resonance dominate our catalog: vertical sloshing of the open magma column in and out of the shallow magma reservoir, and lateral sloshing of magma in the lava lake. These events were triggered mainly from the surface and less commonly from depth. The VLP catalog is then combined with other geophysical datasets to characterize evolution of the shallow magma system. VLP ground motion patterns show both abrupt and gradual changes in shallow magma reservoir geometry. Variation in resonant periods and decay rates of both resonance types occurred on timescales from hours to years, indicating variation in magma density and viscosity that likely reflect unsteady shallow outgassing and convection. A lack of correlation between decay rates of the two dominant resonant modes suggests a decoupling between magma in the conduit and lava lake. Known intrusions and rift zone eruptions often represented change points for resonance characteristics and their relations with other datasets. This data synthesis over a 10‐year eruptive episode at K
lauea Volcano demonstrates how VLP seismicity can sharpen insights into magma system evolution for use in monitoring and understanding eruptive processes.
