Graben formation during the Bárðarbunga rifting event in central Iceland

Handle URI:
http://hdl.handle.net/10754/595122
Title:
Graben formation during the Bárðarbunga rifting event in central Iceland
Authors:
Ruch, Joel; Jonsson, Sigurjon ( 0000-0001-5378-7079 ) ; Wang, Teng ( 0000-0003-3729-0139 ) ; Xu, Wenbin ( 0000-0001-7294-8229 ) ; Trippanera, Daniele
Abstract:
On the 16th of August 2014, an intense seismic swarm was detected at the Bárðarbunga caldera (central Iceland), which migrated to the east and then to the northeast during the following days. The swarm, highlighting magma propagation pathway from the caldera, migrated laterally during the following two weeks over 40 km. By the end of August, a volcanic eruption had started along a north-south oriented fissure located ~45 km from the caldera. Here we focus on the near-field deformation related to the dike emplacement in the shallow crust, which generated in few days an 8 km long by 0.8 km wide graben (depression) structure. The new graben extends from the northern edge of the Vatnajökull glacier and to the north to the eruptive fissure. We analyze the temporal evolution of the graben by integrating structural mapping using multiple acquisitions of TerraSAR-X amplitude radar images, InSAR and ground-truth data with GPS and structural measurements. Pixel-offset tracking of radar amplitude images shows clearly the graben subsidence, directly above the intrusion pathway, of up to 6 meters in the satellite line-of-sight direction. We installed a GPS profile of 15 points across the graben in October 2014 and measured its depth up to 8 meters, relative to the flanks of the graben. Field structural observations show graben collapse structures that typically accompany dike intrusions, with two tilted blocks dipping toward the graben axis, bordered by two normal faults. Extensive fractures at the center of the graben and at the graben edges show a cumulative extension of ~8 meters. The formation of the graben was also accompanied by strong seismic activity locally, constraining the time frame period of the main graben formation subsidence. Our results show a rare case of a graben formation captured from space and from ground observations. Such structures are the dominant features along rift zones, however, their formation remain poorly understood. The results also provide information about transient deformation occurring along rift zones, suggesting that rapid dike intrusions modify the topography permanently in only a few days. This supports that rift morphologies are primarily generated during rifting events rather than by long-term regional tectonic processes.
Conference/Event name:
EGU General Assembly 2015
Issue Date:
Apr-2015
Type:
Presentation
Additional Links:
http://adsabs.harvard.edu/abs/2015EGUGA..1712247R
Appears in Collections:
Presentations

Full metadata record

DC FieldValue Language
dc.contributor.authorRuch, Joelen
dc.contributor.authorJonsson, Sigurjonen
dc.contributor.authorWang, Tengen
dc.contributor.authorXu, Wenbinen
dc.contributor.authorTrippanera, Danieleen
dc.date.accessioned2016-01-28T07:13:56Zen
dc.date.available2016-01-28T07:13:56Zen
dc.date.issued2015-04en
dc.identifier.urihttp://hdl.handle.net/10754/595122en
dc.description.abstractOn the 16th of August 2014, an intense seismic swarm was detected at the Bárðarbunga caldera (central Iceland), which migrated to the east and then to the northeast during the following days. The swarm, highlighting magma propagation pathway from the caldera, migrated laterally during the following two weeks over 40 km. By the end of August, a volcanic eruption had started along a north-south oriented fissure located ~45 km from the caldera. Here we focus on the near-field deformation related to the dike emplacement in the shallow crust, which generated in few days an 8 km long by 0.8 km wide graben (depression) structure. The new graben extends from the northern edge of the Vatnajökull glacier and to the north to the eruptive fissure. We analyze the temporal evolution of the graben by integrating structural mapping using multiple acquisitions of TerraSAR-X amplitude radar images, InSAR and ground-truth data with GPS and structural measurements. Pixel-offset tracking of radar amplitude images shows clearly the graben subsidence, directly above the intrusion pathway, of up to 6 meters in the satellite line-of-sight direction. We installed a GPS profile of 15 points across the graben in October 2014 and measured its depth up to 8 meters, relative to the flanks of the graben. Field structural observations show graben collapse structures that typically accompany dike intrusions, with two tilted blocks dipping toward the graben axis, bordered by two normal faults. Extensive fractures at the center of the graben and at the graben edges show a cumulative extension of ~8 meters. The formation of the graben was also accompanied by strong seismic activity locally, constraining the time frame period of the main graben formation subsidence. Our results show a rare case of a graben formation captured from space and from ground observations. Such structures are the dominant features along rift zones, however, their formation remain poorly understood. The results also provide information about transient deformation occurring along rift zones, suggesting that rapid dike intrusions modify the topography permanently in only a few days. This supports that rift morphologies are primarily generated during rifting events rather than by long-term regional tectonic processes.en
dc.relation.urlhttp://adsabs.harvard.edu/abs/2015EGUGA..1712247Ren
dc.titleGraben formation during the Bárðarbunga rifting event in central Icelanden
dc.typePresentationen
dc.conference.date12-17 April, 2015en
dc.conference.nameEGU General Assembly 2015en
dc.conference.locationVienna, Austriaen
dc.contributor.institutionDipartimento di Scienze, Università Roma Tre, Rome, Italyen
kaust.authorRuch, Joelen
kaust.authorJonsson, Sigurjonen
kaust.authorWang, Tengen
kaust.authorXu, Wenbinen
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