DOI: 10.1016/j.epsl.2018.03.020
Scopus记录号: 2-s2.0-85044524763
论文题名: Long-period seismicity reveals magma pathways above a laterally propagating dyke during the 2014–15 Bárðarbunga rifting event, Iceland
作者: Woods J. ; Donaldson C. ; White R.S. ; Caudron C. ; Brandsdóttir B. ; Hudson T.S. ; Ágústsdóttir T.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2018
卷: 490 起始页码: 216
结束页码: 229
语种: 英语
英文关键词: Bárðarbunga-Holuhraun
; dyke intrusion
; Iceland
; long-period seismicity
; tremor
; volcano seismology
Scopus关键词: Hazards
; Sea level
; Tectonics
; Volcanoes
; Dyke intrusion
; Icelands
; long-period seismicity
; tremor
; Volcano seismology
; Earthquakes
; dike
; earthquake magnitude
; igneous intrusion
; magma chamber
; microtremor
; rifting
; seismic wave
; seismicity
; volcanic earthquake
; volcanic eruption
; Baroarbunga
; Holuhraun
; Iceland
英文摘要: The 2014–15 Bárðarbunga–Holuhraun rifting event comprised the best-monitored dyke intrusion to date and the largest eruption in Iceland in 230 years. A huge variety of seismicity was produced, including over 30,000 volcano-tectonic earthquakes (VTs) associated with the dyke propagation at ∼6 km depth below sea level, and large-magnitude earthquakes accompanying the collapse of Bárðarbunga caldera. We here study the long-period seismicity associated with the rifting event. We systematically detect and locate both long-period events (LPs) and tremor during the dyke propagation phase and the first week of the eruption. We identify clusters of highly similar, repetitive LPs, which have a peak frequency of ∼1 Hz and clear P and S phases followed by a long-duration coda. The source mechanisms are remarkably consistent between clusters and also fundamentally different to those of the VTs. We accurately locate LP clusters near each of three ice cauldrons (depressions formed by basal melting) that were observed on the surface of Dyngjujökull glacier above the path of the dyke. Most events are in the vicinity of the northernmost cauldron, at shallower depth than the VTs associated with lateral dyke propagation. At the two northerly cauldrons, periods of shallow seismic tremor following the clusters of LPs are also observed. Given that the LPs occur at ∼4 km depth and in swarms during times of dyke-stalling, we infer that they result from excitation of magmatic fluid-filled cavities and indicate magma ascent. We suggest that the tremor is the climax of the vertical melt movement, arising from either rapid, repeated excitation of the same LP cavities, or sub-glacial eruption processes. This long-period seismicity therefore represents magma pathways between the depth of the dyke-VT earthquakes and the surface. Notably, we do not detect tremor associated with each cauldron, despite melt reaching the base of the overlying ice cap, a concern for hazard monitoring. © 2018 The Authors Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/109943
Appears in Collections: 影响、适应和脆弱性 气候变化事实与影响
There are no files associated with this item.
作者单位: University of Cambridge, Department of Earth Sciences, Bullard Laboratories, Cambridge, United Kingdom; Royal Observatory of Belgium, Seismology and Gravimetry Section, Uccle, Belgium; G-Time, Département Géosciences, Environnement et Société, Université Libre de Bruxelles, Belgium; Institute of Earth Sciences, University of Iceland, Reykjavík, Iceland
Recommended Citation:
Woods J.,Donaldson C.,White R.S.,et al. Long-period seismicity reveals magma pathways above a laterally propagating dyke during the 2014–15 Bárðarbunga rifting event, Iceland[J]. Earth and Planetary Science Letters,2018-01-01,490