Ambient noise tomography reveals upper crustal structure of Icelandic rifts
The structure of oceanic spreading centres and subsurface melt distribution within newly formed crust is largely understood from marine seismic experiments. In Iceland, however, sub-aerial rift elevation allows both accurate surface mapping and the installation of large broadband seismic arrays. We...
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ftunivcam:oai:www.repository.cam.ac.uk:1810/264166 2024-02-04T10:01:25+01:00 Ambient noise tomography reveals upper crustal structure of Icelandic rifts Green, RG Priestley, KF White, RS 2017-05-15 application/pdf https://www.repository.cam.ac.uk/handle/1810/264166 https://doi.org/10.17863/CAM.9525 eng eng Elsevier http://dx.doi.org/10.1016/j.epsl.2017.02.039 Earth and Planetary Science Letters https://www.repository.cam.ac.uk/handle/1810/264166 doi:10.17863/CAM.9525 Attribution 4.0 International http://creativecommons.org/licenses/by/4.0/ Iceland ambient noise tomography seismic structure spreading centre mid-ocean ridge Article 2017 ftunivcam https://doi.org/10.17863/CAM.9525 2024-01-11T23:21:46Z The structure of oceanic spreading centres and subsurface melt distribution within newly formed crust is largely understood from marine seismic experiments. In Iceland, however, sub-aerial rift elevation allows both accurate surface mapping and the installation of large broadband seismic arrays. We present a study using ambient noise Rayleigh wave tomography to image the volcanic spreading centres across Iceland. Our high resolution model images a continuous band of low seismic velocities, parallelling all three segments of the branched rift in Iceland. The upper 10 km contains strong velocity variations, with shear wave velocities 0.5 km s$^{−1}$ faster in the older non-volcanically active regions compared to the active rifts. Slow velocities correlate very closely with geological surface mapping, with contours of the anomalies parallelling the edges of the neo-volcanic zones. The low-velocity band extends to the full 50 km width of the neo-volcanic zones, demonstrating a significant contrast with the narrow (8 km wide) magmatic zone seen at fast spreading ridges, where the rate of melt supply is similarly high. Within the seismically slow rift band, the lowest velocity cores of the anomalies occur above the centre of the mantle plume under the Vatnajökull icecap, and in the Eastern Volcanic Zone under the central volcano Katla. This suggests localisation of melt accumulation at these specific volcanic centres, demonstrating variability in melt supply into the shallow crust along the rift axis. Shear velocity inversions with depth show that the strongest velocity contrasts are found in the upper 8 km, and show a slight depression in the shear velocity through the mid crust (10–20 km) in the rifts. Our model also shows less intensity to the slow rift anomaly in the Western Volcanic Zone, supporting the notion that rift activity here is decreasing as the ridge jumps to the Eastern Volcanic Zone. Seismometers were borrowed from the Natural Environment Research Council (NERC) SEIS-UK (loans 968 and 1022). The ... Article in Journal/Newspaper Iceland Katla Vatnajökull Apollo - University of Cambridge Repository Vatnajökull ENVELOPE(-16.823,-16.823,64.420,64.420) Katla ENVELOPE(-19.062,-19.062,63.631,63.631) |
institution |
Open Polar |
collection |
Apollo - University of Cambridge Repository |
op_collection_id |
ftunivcam |
language |
English |
topic |
Iceland ambient noise tomography seismic structure spreading centre mid-ocean ridge |
spellingShingle |
Iceland ambient noise tomography seismic structure spreading centre mid-ocean ridge Green, RG Priestley, KF White, RS Ambient noise tomography reveals upper crustal structure of Icelandic rifts |
topic_facet |
Iceland ambient noise tomography seismic structure spreading centre mid-ocean ridge |
description |
The structure of oceanic spreading centres and subsurface melt distribution within newly formed crust is largely understood from marine seismic experiments. In Iceland, however, sub-aerial rift elevation allows both accurate surface mapping and the installation of large broadband seismic arrays. We present a study using ambient noise Rayleigh wave tomography to image the volcanic spreading centres across Iceland. Our high resolution model images a continuous band of low seismic velocities, parallelling all three segments of the branched rift in Iceland. The upper 10 km contains strong velocity variations, with shear wave velocities 0.5 km s$^{−1}$ faster in the older non-volcanically active regions compared to the active rifts. Slow velocities correlate very closely with geological surface mapping, with contours of the anomalies parallelling the edges of the neo-volcanic zones. The low-velocity band extends to the full 50 km width of the neo-volcanic zones, demonstrating a significant contrast with the narrow (8 km wide) magmatic zone seen at fast spreading ridges, where the rate of melt supply is similarly high. Within the seismically slow rift band, the lowest velocity cores of the anomalies occur above the centre of the mantle plume under the Vatnajökull icecap, and in the Eastern Volcanic Zone under the central volcano Katla. This suggests localisation of melt accumulation at these specific volcanic centres, demonstrating variability in melt supply into the shallow crust along the rift axis. Shear velocity inversions with depth show that the strongest velocity contrasts are found in the upper 8 km, and show a slight depression in the shear velocity through the mid crust (10–20 km) in the rifts. Our model also shows less intensity to the slow rift anomaly in the Western Volcanic Zone, supporting the notion that rift activity here is decreasing as the ridge jumps to the Eastern Volcanic Zone. Seismometers were borrowed from the Natural Environment Research Council (NERC) SEIS-UK (loans 968 and 1022). The ... |
format |
Article in Journal/Newspaper |
author |
Green, RG Priestley, KF White, RS |
author_facet |
Green, RG Priestley, KF White, RS |
author_sort |
Green, RG |
title |
Ambient noise tomography reveals upper crustal structure of Icelandic rifts |
title_short |
Ambient noise tomography reveals upper crustal structure of Icelandic rifts |
title_full |
Ambient noise tomography reveals upper crustal structure of Icelandic rifts |
title_fullStr |
Ambient noise tomography reveals upper crustal structure of Icelandic rifts |
title_full_unstemmed |
Ambient noise tomography reveals upper crustal structure of Icelandic rifts |
title_sort |
ambient noise tomography reveals upper crustal structure of icelandic rifts |
publisher |
Elsevier |
publishDate |
2017 |
url |
https://www.repository.cam.ac.uk/handle/1810/264166 https://doi.org/10.17863/CAM.9525 |
long_lat |
ENVELOPE(-16.823,-16.823,64.420,64.420) ENVELOPE(-19.062,-19.062,63.631,63.631) |
geographic |
Vatnajökull Katla |
geographic_facet |
Vatnajökull Katla |
genre |
Iceland Katla Vatnajökull |
genre_facet |
Iceland Katla Vatnajökull |
op_relation |
https://www.repository.cam.ac.uk/handle/1810/264166 doi:10.17863/CAM.9525 |
op_rights |
Attribution 4.0 International http://creativecommons.org/licenses/by/4.0/ |
op_doi |
https://doi.org/10.17863/CAM.9525 |
_version_ |
1789967282101813248 |