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- Geoffroy, Laurent, et al.
(author)
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Hydrothermal fluid flow triggered by an earthquake in Iceland
- 2022
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In: Communications Earth & Environment. - : Springer Nature. - 2662-4435. ; 3:1
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Journal article (peer-reviewed)abstract
- Microearthquake hypocenters were analyzed in the Krysuvik geothermal area in SW-Iceland with data taken from two consecutive passive seismic surveys, 2005 and 2009. Five years prior to the 2005 survey, this area was struck by an earthquake initiating a major top-tobottom fluid migration in the upper crust. We observe from our surveys a complex bottomto-top migration of seismicity with time following this fluid penetration, suggesting the migration of a pore pressure front controlled by the upper-crust fracture system. We interpret these data as the time and space development of high-temperature hydrothermal cells from a deep upper crustal fluid reservoir in the supercritical field. These results provide an insight into the coupling mechanisms between active tectonics and fluid flow in upper-crustal extensional systems with high thermal flux.
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- Kim, Doyeon, et al.
(author)
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Magma "bright spots" mapped beneath Krafla, Iceland, using RVSP imaging of reflected waves from microearthquakes
- 2020
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In: Journal of Volcanology and Geothermal Research. - : ELSEVIER. - 0377-0273 .- 1872-6097. ; 391
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Journal article (peer-reviewed)abstract
- The geometry and distribution of magma in the crust remain controversial topics with recent studies questioning the role of large magma chambers. In this investigation, high-resolution 3D reflection images of crustal discontinuities beneath the Krafla geothermal field in northern Iceland were generated by applying Vertical Seismic Profiling (VSP) techniques adapted from reflection seismology to microearthquake data. Exceptionally large amplitude reflections (bright spots) at a depth of 2.1 km correlate with rhyolitic magma encountered in the IDDP-1 borehole. Although similarly bright reflectors at about 4 km correspond in depth to the top of an inferred magma chamber from previous seismic studies, the scattered reflectivity that persists beneath this deeper reflector argues for a distributed magma system rather than a large feeder chamber.
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