Local Earthquake Tomography in the Tjörnes Fracture Zone (North Iceland)
Local earthquake tomography has been carried out in the Tjornes Fracture Zone. This transform region connects the Mid-Atlantic Ridge to the Northern Volcanic Zone in Iceland in a mostly offshore area. The challenge to record seismic information in this area was the motivation for the North ICeland E...
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Uppsala universitet, Geofysik
2021
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ftuppsalauniv:oai:DiVA.org:uu-363252 2024-02-11T10:04:30+01:00 Local Earthquake Tomography in the Tjörnes Fracture Zone (North Iceland) Abril, Claudia Tryggvason, Ari Gudmundsson, Ólafur Steffen, Rebekka 2021 application/pdf http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-363252 https://doi.org/10.1029/2020JB020212 eng eng Uppsala universitet, Geofysik Icelandic Meteorol Off IMO, Reykjavik, Iceland. Lantmäteriet, Gävle, Sweden. Journal of Geophysical Research - Solid Earth, 2169-9313, 2021, 126:6, orcid:0000-0002-3365-8613 orcid:0000-0002-2511-187X http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-363252 doi:10.1029/2020JB020212 ISI:000665206200017 info:eu-repo/semantics/openAccess Geophysics Geofysik Article in journal info:eu-repo/semantics/article text 2021 ftuppsalauniv https://doi.org/10.1029/2020JB020212 2024-01-17T23:31:56Z Local earthquake tomography has been carried out in the Tjornes Fracture Zone. This transform region connects the Mid-Atlantic Ridge to the Northern Volcanic Zone in Iceland in a mostly offshore area. The challenge to record seismic information in this area was the motivation for the North ICeland Experiment (NICE). Fourteen ocean-bottom seismometers and eleven on-land stations were installed in the project and operated simultaneously with the permanent Icelandic seismic network (SIL) during summer 2004. Data from the experiment were used to estimate P- and S-wave crustal velocities. Also, the gravity anomaly was derived for comparison with the tomographic results. Upper-crustal velocities are found to be relatively low in the offshore region. In particular, low velocities are mapped along the Husavik-Flatey Fault, where a more confined negative gravity anomaly and a sedimentary basin are found. Low velocities are also mapped along the Grimsey Oblique Rift and in a zone connecting these two main lineaments. The northern half of the aseismic Grimsey Shoal appears as a fast anomaly. Furthermore, localized high-velocity anomalies are found beneath northern Trollaskagi and Flateyjarskagi Peninsulas, where bedrock dates from Upper and Middle Miocene (10-15 Ma). Regions of low Vp/Vs ratios are mapped at depth along the main lineaments. Low velocities along the lineaments are interpreted as due to fracturing extending into the middle crust, while high velocities in the upper crust beneath Tertiary formations are associated with relic volcanoes. Low Vp/Vs variations along the lineaments are interpreted as due to the presence of supercritical fluids. Title in dissertation list of papers: Local earthquake tomography and earthquake relocation in the Tjörnes Fracture Zone (North Iceland) Article in Journal/Newspaper Grimsey Iceland Flatey Uppsala University: Publications (DiVA) Husavik ENVELOPE(-17.345,-17.345,66.046,66.046) Mid-Atlantic Ridge Tjörnes ENVELOPE(-17.087,-17.087,66.152,66.152) Journal of Geophysical Research: Solid Earth 126 6 |
institution |
Open Polar |
collection |
Uppsala University: Publications (DiVA) |
op_collection_id |
ftuppsalauniv |
language |
English |
topic |
Geophysics Geofysik |
spellingShingle |
Geophysics Geofysik Abril, Claudia Tryggvason, Ari Gudmundsson, Ólafur Steffen, Rebekka Local Earthquake Tomography in the Tjörnes Fracture Zone (North Iceland) |
topic_facet |
Geophysics Geofysik |
description |
Local earthquake tomography has been carried out in the Tjornes Fracture Zone. This transform region connects the Mid-Atlantic Ridge to the Northern Volcanic Zone in Iceland in a mostly offshore area. The challenge to record seismic information in this area was the motivation for the North ICeland Experiment (NICE). Fourteen ocean-bottom seismometers and eleven on-land stations were installed in the project and operated simultaneously with the permanent Icelandic seismic network (SIL) during summer 2004. Data from the experiment were used to estimate P- and S-wave crustal velocities. Also, the gravity anomaly was derived for comparison with the tomographic results. Upper-crustal velocities are found to be relatively low in the offshore region. In particular, low velocities are mapped along the Husavik-Flatey Fault, where a more confined negative gravity anomaly and a sedimentary basin are found. Low velocities are also mapped along the Grimsey Oblique Rift and in a zone connecting these two main lineaments. The northern half of the aseismic Grimsey Shoal appears as a fast anomaly. Furthermore, localized high-velocity anomalies are found beneath northern Trollaskagi and Flateyjarskagi Peninsulas, where bedrock dates from Upper and Middle Miocene (10-15 Ma). Regions of low Vp/Vs ratios are mapped at depth along the main lineaments. Low velocities along the lineaments are interpreted as due to fracturing extending into the middle crust, while high velocities in the upper crust beneath Tertiary formations are associated with relic volcanoes. Low Vp/Vs variations along the lineaments are interpreted as due to the presence of supercritical fluids. Title in dissertation list of papers: Local earthquake tomography and earthquake relocation in the Tjörnes Fracture Zone (North Iceland) |
format |
Article in Journal/Newspaper |
author |
Abril, Claudia Tryggvason, Ari Gudmundsson, Ólafur Steffen, Rebekka |
author_facet |
Abril, Claudia Tryggvason, Ari Gudmundsson, Ólafur Steffen, Rebekka |
author_sort |
Abril, Claudia |
title |
Local Earthquake Tomography in the Tjörnes Fracture Zone (North Iceland) |
title_short |
Local Earthquake Tomography in the Tjörnes Fracture Zone (North Iceland) |
title_full |
Local Earthquake Tomography in the Tjörnes Fracture Zone (North Iceland) |
title_fullStr |
Local Earthquake Tomography in the Tjörnes Fracture Zone (North Iceland) |
title_full_unstemmed |
Local Earthquake Tomography in the Tjörnes Fracture Zone (North Iceland) |
title_sort |
local earthquake tomography in the tjörnes fracture zone (north iceland) |
publisher |
Uppsala universitet, Geofysik |
publishDate |
2021 |
url |
http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-363252 https://doi.org/10.1029/2020JB020212 |
long_lat |
ENVELOPE(-17.345,-17.345,66.046,66.046) ENVELOPE(-17.087,-17.087,66.152,66.152) |
geographic |
Husavik Mid-Atlantic Ridge Tjörnes |
geographic_facet |
Husavik Mid-Atlantic Ridge Tjörnes |
genre |
Grimsey Iceland Flatey |
genre_facet |
Grimsey Iceland Flatey |
op_relation |
Journal of Geophysical Research - Solid Earth, 2169-9313, 2021, 126:6, orcid:0000-0002-3365-8613 orcid:0000-0002-2511-187X http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-363252 doi:10.1029/2020JB020212 ISI:000665206200017 |
op_rights |
info:eu-repo/semantics/openAccess |
op_doi |
https://doi.org/10.1029/2020JB020212 |
container_title |
Journal of Geophysical Research: Solid Earth |
container_volume |
126 |
container_issue |
6 |
_version_ |
1790601107948437504 |