Papers by Magnús Á. Sigurgeirsson
Journal of geomagnetism and geoelectricity, 1993
We present the results of geological and palaeomagnetic mapping of several lava profiles in South... more We present the results of geological and palaeomagnetic mapping of several lava profiles in Southwestern Iceland, covering a transition from reverse to normal polarity about 2 M.y. ago. The transition was first described by . We confirm that the virtual-pole path of this transition is not confined in longitude. We also present and discuss instances of complex pole paths in older strata in Iceland, and we provide new evidence for the general reliability of palaeomagnetic directions from lava flows.
Journal of Volcanology and Geothermal Research, Feb 1, 2020
The Reykjanes Peninsula is a trans-tensional plate boundary with several volcanic systems from th... more The Reykjanes Peninsula is a trans-tensional plate boundary with several volcanic systems from the centers of which fissure swarms extend to the NE and SW. The fissure swarms accommodate the extensional component, whereas north-south trending strike-slip faults accomodate the transform component. The fissure swarms release stress during volcano-tectonic episodes that occur at intervals of several hundred years. Stress is released by the strike-slip faults by microearthquake swarms at intervals of a few decades. The fissure swarms are segmented along their trend. The segments include a volcanic center with a clustering of fissure eruptions and extensional faults. A proximal zone of 20-40 km follows were faults become dominant with distance from the cener. Linear anomalies of a high geothermal gradient extend further still, into the marginal area of Early Quaternary to Miocene rocks indicating dyke propagation for another 30-40 km beyond visible faults. The Reykjanes volcanic center is nested in a 5-6 km wide rift zone with boundary faults of just over 20 m visible throw. Volcanic production keeps pace with extension and subsidence to fill the rift. The last three volcano-tectonic episodes occurred at Reykjanes in the 13. century, about 2000 years ago and about 3200 years ago. The lavas from these three fissure eruptions cover more than 2/3 of Reykjanes by area, largely smoothing over faults of the rift floor. During the Weichselian glacial maximum the ice margin may have reached 75-100 km beyond Reykjanes. It
EGU General Assembly Conference Abstracts, Apr 1, 2018
Journal of Volcanology and Geothermal Research, 2018
One of the World's premier field geologists, Kristján Saemundsson led immense geological mapping ... more One of the World's premier field geologists, Kristján Saemundsson led immense geological mapping programs and authored or co-authored nearly all geological maps of Iceland during the past half century, including the first modern bedrock and tectonic maps of the whole country. These monumental achievements collectively yield the most inclusive view of an extensional plate boundary anywhere on Earth. When Kristján began his work in 1961, the relation of Iceland to sea-floor spreading was not clear, and plate tectonics had not yet been invented. Kristján resolved key obstacles by demonstrating that the active rifting zones in Iceland had shifted over time and were linked by complex transforms to the mid-ocean spreading ridge, thus making the concept of sea-floor spreading in Iceland acceptable to those previously skeptical. Further, his insights and vast geological and tectonic knowledge on both high-and low-temperature geothermal areas in Iceland yielded a major increase in knowledge of geothermal systems, and probably no one has contributed more than he to Icelandic energy development. Kristján's legacy is comprised by his numerous superb maps on a variety of scales, the high quality papers he produced, the impactful ideas generated that were internationally diffused, and the generations of colleagues and younger people he inspired, mentored, or otherwise positively influenced with his knowledge and generous attitude.
Um nokkurt skeið hefur ferðamönnum sem leið eiga um Haukadal og nágrenni staðið til boða að skoða... more Um nokkurt skeið hefur ferðamönnum sem leið eiga um Haukadal og nágrenni staðið til boða að skoða eftirlíkingu af bæ Eiríks rauða á Eiríksstöðum þar sem hægt er að skoða líflega kynningu á lifnaðar- og hýbýlaháttum Íslendinga á söguöld. Hefur aðsókn á staðinn verið talsverð síðan Eiríksbær var opnaður almenningi og af þeim sökum vaknað sú umræða hvort ekki væri hægt að auka enn frekar við menningartengda ferðaþjónustu á svæðinu. Í því samhengi hafa heimamenn lýst áhuga á því að blása lífi í fornleifarannsóknir í Haukadal og eru þær rannsóknir sem fram fóru sumarið 2009 liður í þeirri áætlun. Í maí 2009 fóru fornleifafræðingar frá Fornleifastofnun Íslands, Oddgeir Hansson, Guðrún Alda Gísladóttir og Hildur Gestsdóttir, í vettvangsferð með Óskari Inga Ingasyni, sóknarpresti Dalaprestakalls og stjórnarmanni í Fornleifafélag Barðstrendinga og Dalamanna, í Haukadal og heimsóttu minjastaði. Þar kviknaði sú hugmynd að dalurinn byði upp á mikla möguleika til rannsókna á búskapar- og hýbýlah...
Radioprotection, 2002
Iceland was identified in the Arctic Monitoring and Assessment Report as one of the Arctic areas ... more Iceland was identified in the Arctic Monitoring and Assessment Report as one of the Arctic areas which received the most global fallout from atmospheric nuclear weapons tests, but measurements of contamination were sparse, and are difficult due to the remote and inaccessible terrain of much of the country. Measurements of global 137 Cs deposition have been made at sites close to meteorological stations to ensure that precipitation data were of high quality. The measured data have been compared with different methods of predicting ,37 Cs deposition. The AMAP modeling approach, based on fallout and precipitation data, was used based on a monitoring station near Reykjavik. The availability of good precipitation data and locally based estimates of time dependent ratios of 137 Cs deposition to precipitation during the fallout period gave a better correlation between predicted and observed 137 Cs deposition (1^=0.96) than that achieved using the heterogeneous set of data collected by AMAP over the whole of the Arctic. The method allows a fallout map to be produced for the whole of Iceland for any time period during or after deposition.
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Papers by Magnús Á. Sigurgeirsson