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A Preseismic Strain Anomaly Detected Before M6 Earthquakes in the South Iceland Seismic Zone From GPS Station Velocities

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dc.contributor Háskóli Íslands
dc.contributor University of Iceland
dc.contributor.author Arnadottir, Thora
dc.contributor.author Haines, John
dc.contributor.author Geirsson, Halldor
dc.contributor.author Hreinsdóttir, Sigrún
dc.date.accessioned 2019-08-13T14:08:06Z
dc.date.available 2019-08-13T14:08:06Z
dc.date.issued 2018-12
dc.identifier.citation Árnadóttir, T., Haines, J., Geirsson, H., & Hreinsdóttir, S. (2018). A Preseismic Strain Anomaly Detected Before M6 Earthquakes in the South Iceland Seismic Zone From GPS Station Velocities. Journal of Geophysical Research: Solid Earth, 123(12), 11,091-011,111. doi:10.1029/2018jb016068
dc.identifier.issn 2169-9313
dc.identifier.uri https://hdl.handle.net/20.500.11815/1211
dc.description Publisher's version (útgefin grein)
dc.description.abstract The South Iceland Seismic Zone (SISZ) accommodates E‐W translation due to oblique spreading between the North American and the Eurasian plates in South Iceland with ruptures on N‐S faults. Strain is released in earthquake sequences that last days to years, at average intervals of 80–100 years. Two M6.5 earthquakes struck in the SISZ in June 2000, and two M6 earthquakes in May 2008. These events released only half of the strain accumulated since the last earthquake sequence in 1896–1912. GPS station velocities are estimated from annual campaigns and continuous measurements in the SISZ during 2001–2015. The GPS station velocities are used to calculate strain rates from a new method using the vertical derivatives of horizontal stress. Our new strain rates are obtained by integrating vertical derivatives of horizontal stress rates, rather than differentiating interpolated GPS velocities, allowing finer resolution of strain. Estimating the strain rates for eight time intervals, we find high strain rates in the SISZ (0.5–1 microstrain per year) with significant temporal and spatial variation. The strain rates in the SISZ reveal contraction in the Hengill area and dilatation over a large area in eastern SISZ, indicating inflation of the magma system beneath Hekla volcano. A prominent strain anomaly is evident in the epicentral area prior to the May 2008 earthquakes. We suggest that this signal is primarily caused by plate motion and an increase in the rate of contraction in the Hengill area, located ∼10 km west of the epicentral area.
dc.description.sponsorship This study was funded by grants from the Icelandic Research Fund (grants 0315900-03/04/05, 060243-011/012/013, 090237-021/022/023, and 130371-051/052/053), the Icelandic Equipment Fund (grant 061059), and the University of Iceland Research fund (grant HI-6489).
dc.format.extent 11,091-11,111
dc.language.iso en
dc.publisher American Geophysical Union (AGU)
dc.relation.ispartofseries Journal of Geophysical Research: Solid Earth;123(12)
dc.rights info:eu-repo/semantics/openAccess
dc.subject Crustal deformation
dc.subject Strain rates
dc.subject Earthquake sequence
dc.subject Extraction of geothermal fluids
dc.subject Magma accumulation
dc.subject Postseismic transients
dc.subject Jarðskorpa
dc.subject Jarðskjálftar
dc.subject Bergkvika
dc.title A Preseismic Strain Anomaly Detected Before M6 Earthquakes in the South Iceland Seismic Zone From GPS Station Velocities
dc.type info:eu-repo/semantics/article
dcterms.license This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made
dc.description.version Peer Reviewed
dc.identifier.journal Journal of Geophysical Research: Solid Earth
dc.identifier.doi 10.1029/2018JB016068
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)

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