Present kinematics of the Tjornes Fracture Zone, North Iceland, from campaign and continuous GPS measurements

Handle URI:
http://hdl.handle.net/10754/555753
Title:
Present kinematics of the Tjornes Fracture Zone, North Iceland, from campaign and continuous GPS measurements
Authors:
Metzger, S.; Jonsson, Sigurjon ( 0000-0001-5378-7079 ) ; Danielsen, G.; Hreinsdottir, S.; Jouanne, F.; Giardini, D.; Villemin, T.
Abstract:
The Tjörnes Fracture Zone (TFZ), North Iceland, is a 120 km transform offset of the Mid-Atlantic-Ridge that accommodates 18 mm yr−1 plate motion on two parallel transform structures and connects the offshore Kolbeinsey Ridge in the north to the on-shore Northern Volcanic Zone (NVZ) in the south. This transform zone is offshore except for a part of the right-lateral strike-slip Húsavík-Flatey fault (HFF) system that lies close to the coastal town of Húsavík, inducing a significant seismic risk to its inhabitants. In our previous work we constrained the locking depth and slip-rate of the HFF using 4 yr of continuous GPS measurements and found that the accumulated slip-deficit on the fault is equivalent to a Mw6.8 ± 0.1 earthquake, assuming a complete stress release in the last major earthquakes in 1872 and a steady accumulation since then. In this paper we improve our previous analysis by adding 44 campaign GPS (EGPS) data points, which have been regularly observed since 1997. We extract the steady-state interseismic velocities within the TFZ by correcting the GPS data for volcanic inflation of Theistareykir—the westernmost volcano of the NVZ—using a model with a magma volume increase of 25 × 106 m3, constrained by InSAR time-series analysis results. The improved velocity field based on 58 GPS stations confirms the robustness of our previous model and allows to better constrain the free model parameters. For the HFF we find a slightly shallower locking depth of ∼6.2 km and a slightly higher slip-rate of ∼6.8 mm yr−1 that again result in the same seismic potential equivalent to a Mw6.8 earthquake. The much larger number of GPS velocities improves the statistically estimated model parameter uncertainties by a factor of two, when compared to our previous study, a result that we validate using Bayesian estimation.
KAUST Department:
Physical Sciences and Engineering (PSE) Division
Citation:
Present kinematics of the Tjornes Fracture Zone, North Iceland, from campaign and continuous GPS measurements 2012, 192 (2):441 Geophysical Journal International
Publisher:
Oxford University Press (OUP)
Journal:
Geophysical Journal International
Issue Date:
19-Nov-2012
DOI:
10.1093/gji/ggs032
Type:
Article
ISSN:
0956-540X; 1365-246X
Additional Links:
http://gji.oxfordjournals.org/cgi/doi/10.1093/gji/ggs032
Appears in Collections:
Articles; Physical Sciences and Engineering (PSE) Division; Physical Sciences and Engineering (PSE) Division

Full metadata record

DC FieldValue Language
dc.contributor.authorMetzger, S.en
dc.contributor.authorJonsson, Sigurjonen
dc.contributor.authorDanielsen, G.en
dc.contributor.authorHreinsdottir, S.en
dc.contributor.authorJouanne, F.en
dc.contributor.authorGiardini, D.en
dc.contributor.authorVillemin, T.en
dc.date.accessioned2015-05-26T07:14:24Zen
dc.date.available2015-05-26T07:14:24Zen
dc.date.issued2012-11-19en
dc.identifier.citationPresent kinematics of the Tjornes Fracture Zone, North Iceland, from campaign and continuous GPS measurements 2012, 192 (2):441 Geophysical Journal Internationalen
dc.identifier.issn0956-540Xen
dc.identifier.issn1365-246Xen
dc.identifier.doi10.1093/gji/ggs032en
dc.identifier.urihttp://hdl.handle.net/10754/555753en
dc.description.abstractThe Tjörnes Fracture Zone (TFZ), North Iceland, is a 120 km transform offset of the Mid-Atlantic-Ridge that accommodates 18 mm yr−1 plate motion on two parallel transform structures and connects the offshore Kolbeinsey Ridge in the north to the on-shore Northern Volcanic Zone (NVZ) in the south. This transform zone is offshore except for a part of the right-lateral strike-slip Húsavík-Flatey fault (HFF) system that lies close to the coastal town of Húsavík, inducing a significant seismic risk to its inhabitants. In our previous work we constrained the locking depth and slip-rate of the HFF using 4 yr of continuous GPS measurements and found that the accumulated slip-deficit on the fault is equivalent to a Mw6.8 ± 0.1 earthquake, assuming a complete stress release in the last major earthquakes in 1872 and a steady accumulation since then. In this paper we improve our previous analysis by adding 44 campaign GPS (EGPS) data points, which have been regularly observed since 1997. We extract the steady-state interseismic velocities within the TFZ by correcting the GPS data for volcanic inflation of Theistareykir—the westernmost volcano of the NVZ—using a model with a magma volume increase of 25 × 106 m3, constrained by InSAR time-series analysis results. The improved velocity field based on 58 GPS stations confirms the robustness of our previous model and allows to better constrain the free model parameters. For the HFF we find a slightly shallower locking depth of ∼6.2 km and a slightly higher slip-rate of ∼6.8 mm yr−1 that again result in the same seismic potential equivalent to a Mw6.8 earthquake. The much larger number of GPS velocities improves the statistically estimated model parameter uncertainties by a factor of two, when compared to our previous study, a result that we validate using Bayesian estimation.en
dc.publisherOxford University Press (OUP)en
dc.relation.urlhttp://gji.oxfordjournals.org/cgi/doi/10.1093/gji/ggs032en
dc.rightsArchived with thanks to Geophysical Journal International © The Authors 2012. Published by Oxford University Press on behalf of The Royal Astronomical Society.en
dc.subjectTime series analysisen
dc.subjectNumerical approximations and analysisen
dc.subjectSatellite geodesy, Radar interferometryen
dc.subjectOceanic transform and fracture zone processesen
dc.subjectKinematics of crustal and mantle deformationen
dc.titlePresent kinematics of the Tjornes Fracture Zone, North Iceland, from campaign and continuous GPS measurementsen
dc.typeArticleen
dc.contributor.departmentPhysical Sciences and Engineering (PSE) Divisionen
dc.identifier.journalGeophysical Journal Internationalen
dc.eprint.versionPublisher's Version/PDFen
dc.contributor.institutionInstitute of Geophysics, ETH Zürich, Sonneggstrasse 5, 8092 Zürich, Switzerlanden
dc.contributor.institutionNordic Volcanological Center, Institute of Earth Sciences, University of Iceland, Icelanden
dc.contributor.institutionUniversité de Savoie, Bourget-du-Lac, Franceen
kaust.authorJonsson, Sigurjonen
kaust.authorDanielsen, Gillisen
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