dc.contributor |
Háskóli Íslands (HÍ) |
dc.contributor |
University of Iceland (UI) |
dc.contributor.author |
Woods, Jennifer |
dc.contributor.author |
Donaldson, Clare |
dc.contributor.author |
White, Robert S. |
dc.contributor.author |
Caudron, Corentin |
dc.contributor.author |
Brandsdóttir, Bryndís |
dc.contributor.author |
Hudson, Thomas S. |
dc.contributor.author |
Agustsdottir, Thorbjorg |
dc.date.accessioned |
2020-01-27T16:13:37Z |
dc.date.available |
2020-01-27T16:13:37Z |
dc.date.issued |
2018-05-15 |
dc.identifier.citation |
Woods, J. et al., 2018. Long-period seismicity reveals magma pathways above a laterally propagating dyke during the 2014–15 Bárðarbunga rifting event, Iceland. Earth and Planetary Science Letters, 490(C), pp.216–229. |
dc.identifier.issn |
0012-821X |
dc.identifier.uri |
https://hdl.handle.net/20.500.11815/1481 |
dc.description |
Publisher's version (útgefin grein). |
dc.description.abstract |
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. |
dc.description.sponsorship |
Seismometers were borrowed from the Natural Environment
Research Council (NERC) SEIS-UK [loans 968 and 1022], with funding by research grants from the NERC and the European Community’s Seventh Framework Programme [grant 308377, Project
FUTUREVOLC], and graduate studentships from the NERC (NE/
L002507/1). C.C. acknowledges a Wiener-Anspach postdoctoral fellowship and an F.R.S.-FNRS Chargé de Recherches/Université Libre
de Bruxelles fellowship. We thank Sveinbjörn Steinþórsson and
others who assisted with fieldwork in Iceland, and Jürgen Neuberg, Andy Hooper, Jean Soubestre and others for their helpful
discussions. The Icelandic Meteorological Office, Chris Bean (University College Dublin), and the British Geological Survey kindly
provided additional data from seismometers in northeast Iceland,
data delivery from IMO seismic database 20151001/01. Earthquake
hypocentres can be found in Ágústsdóttir et al. (2016). The raw
seismic data are archived at Cambridge University and will be
available at IRIS for download from October 2019. The GISMO toolbox is freely available from https://geoscience-community-codes.
github.io/GISMO/ and the MTfit software for moment tensor inversion is freely available from https://github.com/djpugh/MTfit. We
thank reviewers Nikolai Shapiro and Tony Hurst for their constructive comments. The first two authors contributed equally to
this paper. Department of Earth Sciences, Cambridge contribution
ESC.4091. |
dc.format.extent |
216-229 |
dc.language.iso |
en |
dc.publisher |
Elsevier BV |
dc.relation |
info:eu-repo/grantAgreement/EC/FP7/308377 |
dc.relation.ispartofseries |
Earth and Planetary Science Letters;490 |
dc.rights |
info:eu-repo/semantics/openAccess |
dc.subject |
Bárðarbunga |
dc.subject |
Dyke intrusion |
dc.subject |
Long-period seismicity |
dc.subject |
Tremor |
dc.subject |
Volcano seismology |
dc.subject |
Iceland |
dc.subject |
Jarðskjálftar |
dc.subject |
Eldfjöll |
dc.subject |
Eldgos |
dc.subject |
Berggangar |
dc.subject |
Holuhraun |
dc.title |
Long-period seismicity reveals magma pathways above a laterally propagating dyke during the 2014–15 Bárðarbunga rifting event, Iceland |
dc.type |
info:eu-repo/semantics/article |
dcterms.license |
This is an open access article under the CC BY license
(http://creativecommons.org/licenses/by/4.0/). |
dc.description.version |
Peer Reviewed |
dc.identifier.journal |
Earth and Planetary Science Letters |
dc.identifier.doi |
10.1016/j.epsl.2018.03.020 |
dc.contributor.department |
Jarðvísindastofnun (HÍ) |
dc.contributor.department |
Institute of Earth Sciences (UI) |
dc.contributor.school |
Verkfræði- og náttúruvísindasvið (HÍ) |
dc.contributor.school |
School of Engineering and Natural Sciences (UI) |