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Browsing by Author "Bjarnason, Ingi Þorleifur"

Browsing by Author "Bjarnason, Ingi Þorleifur"

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  • Bjarnason, Ingi Þorleifur (Hið íslenska náttúrufræðifélag, 1997)
    Heitur reitur er landsvæði sem einkennist af mikilli eldvirkni og jarðhita og stendur hátt yfir umhverfið. Ísland er einn af stærstu heitu reitum jarðar og gnæfir 2-4 km yfir venjulega hæð Norður-Atlantshafshryggjarins sem gengur í gegnum landið. Markmið ...
  • Bjarnason, Ingi Þorleifur; Cowie, Patience; Anders, Mark H.; Seeber, Leonardo; Scholz, Christopher H. (The Seismological Society of America, 1993)
    We have mapped in detail surface ruptures of the 1912 magnitude 7.0 strike-slip earthquake in south Iceland. This earthquake ruptured fresh basalt flows that had covered the pre-existing fault. The observed style of surface fracturing closely matches ...
  • Bjarnason, Ingi Þorleifur; Menke, William (Society of Exploration Geophysicists, 1993-07)
    Cross-borehole tomography suffers from a well-known problem of data incompleteness: the limited ray coverage dictated by the poor experimental geometry implies that certain features of the velocity field are not determined by the data. Construction of ...
  • Wolfe, Cecily J.; Bjarnason, Ingi Þorleifur; VanDecar, John C.; Solomon, Sean C. (Wiley-Blackwell, 2002)
    Earlier inversions of body wave delay-time data recorded during the ICEMELT portable broadband experiment imaged a cylindrical plume-like low-velocity anomaly extending to at least 400 km depth beneath Iceland, but the depth extent of the anomaly ...
  • Bjarnason, Ingi Þorleifur; Pechmann, James C. (The Seismological Society of America, 1989)
    We have completed a comprehensive study of focal mechanisms of digitally recorded earthquakes (M, -_< 4.4) that occurred in the Wasatch front region in Utah during 1980 to 1986. Single-event solutions for 24 events were determined using recently ...
  • Darbyshire, Fiona A.; Bjarnason, Ingi Þorleifur; White, Robert S.; Flóvenz, Ólafur G. (Oxford University Press (OUP), 1998-12)
    The crustal structure of central Iceland is modelled using data from a 310 km long refraction profile shot during summer 1995. The profile traversed Iceland from the Skagi Peninsula on the north coast (surface rocks of age 8.5–0.8 Myr) to the southeast ...
  • Bjarnason, Ingi Þorleifur (Iceland Glaciological Society and Geoscience Society of IcelandJöklarannsóknafélags Íslands og Jarðfræðafélags Íslands, 2014)
    A day and a half after the earthquake (mb=5.3, MS=5.6, MW=5.6) in the Bárðarbunga central volcano on Sept. 29th 1996, a volcanic eruption broke out under the Vatnajökull glacier. The eruption was located approximately 20 km SSE of the earthquake ...
  • Wilcock, William S. D.; Webb, Spahr C.; Bjarnason, Ingi Þorleifur (The Seismological Society of America, 1999)
    The mantle electromagnetic and tomography (MELT) experiment on the east Pacific rise near 17°S was the first large teleseismic experiment on a midocean ridge. During the six-month deployment, no compressional arrivals were well recorded above 0.5 ...
  • Shen, Yang; Solomon, Sean C.; Bjarnason, Ingi Þorleifur; Purdy, G. M. (American Geophysical Union (AGU), 1996-12-01)
    P‐to‐S conversions from the two primary discontinuities near 410 and 660 km depth (P410s and P660s phases) are evident in particle motions and receiver functions of teleseismic body waves recorded by broadband seismic stations in Iceland. The average ...
  • Bjarnason, Ingi Þorleifur (Iceland Glaciological Society and Geoscience Society of IcelandJöklarannsóknafélags Íslands og Jarðfræðafélags Íslands, 2008)
    Is Iceland a hotspot, with ridge-centered plume? In Iceland vigorous volcanism has built up a plateau 3.0 km higher than at a normal mid-ocean ridge with 3 to 4 times thicker crust than average oceanic crust. This volcanism can be associated with ...
  • Bjarnason, Ingi Þorleifur; Wolfe, Cecily J.; Solomon, Sean C.; Guðmundsson, Gunnar (Wiley-Blackwell, 1996-03-01)
    We present results from the first stage of the ICEMELT broadband seismometer experiment designed to determine upper mantle structure beneath Iceland, a hotspot located on the Mid-Atlantic Ridge. Relative delays of teleseismic body waves across Iceland ...
  • Bjarnason, Ingi Þorleifur; Schmeling, Harro (Oxford University Press (OUP), 2009-07)
    1-D models were calculated for the velocity of shear waves, polarized vertically (SV) and horizontally (SH) from dispersed Rayleigh and Love surface waves. These had been recorded in Iceland by the ICEMELT broad-band seismic network, with about half ...
  • Menke, William; Brandsdóttir, Bryndís; Einarsson, Páll; Bjarnason, Ingi Þorleifur (Oxford University Press (OUP), 1996-07)
    Two shear-wave profiles, E and G, collected during the 1977 Reykjanes Ridge Iceland Seismic Experiment have played an important role in models of the Icelandic crust. They were originally interpreted as indicating very low shear-wave velocities and ...
  • Shen, Yang; Solomon, Sean C.; Bjarnason, Ingi Þorleifur; Wolfe, Cecily J. (Springer Nature, 1998-09)
    Iceland, one of the most thoroughly investigated hotspots1,2,3, is generally accepted to be the manifestation of an upwelling mantle plume4. Yet whether the plume originates from the lower mantle or from a convective instability at a thermal boundary ...
  • Shen, Yang; Solomon, Sean C.; Bjarnason, Ingi Þorleifur; Nolet, Guust; Morgan, W.Jason; Allen, Richard M.; Vogfjörð, Kristín; Jakobsdóttir, Steinunn; Stefánsson, Ragnar; Julian, B.R.; Foulger, G.R. (Elsevier BV, 2002-04)
    Shear waves converted from compressional waves at mantle discontinuities near 410- and 660-km depth recorded by two broadband seismic experiments in Iceland reveal that the center of an area of anomalously thin mantle transition zone lies at least 100 ...
  • Bjarnason, Ingi Þorleifur; Silver, Paul G.; Rümpker, Georg; Solomon, Sean C. (Wiley-Blackwell, 2002-12)
    We report on observations of upper mantle anisotropy from the splitting of teleseismic shear waves (SKS, SKKS, and PKS) recorded by the ICEMELT broadband seismometer network in Iceland. In a ridge-centered hot spot locale, mantle anisotropy may be ...
  • Bjarnason, Ingi Þorleifur; Einarsson, Páll (American Geophysical Union (AGU), 1991-03-10)
    The May 25, 1987, Vatnafjöll earthquake occurred on the Mid‐Atlantic plate boundary, at a junction between a transform (the South Iceland Seismic Zone) and a spreading segment (the Eastern Volcanic Zone). The South Iceland Seismic Zone has had the most ...
  • Kreutzmann, A.; Schmeling, Harro; Junge, A.; Ruedas, T.; Marquart, G.; Bjarnason, Ingi Þorleifur (Oxford University Press (OUP), 2004-12)
    The dynamic and melting processes of a ridge-centred plume have been investigated in a companion paper by Ruedas et al. (hereafter referred to as Paper I) in a set of 3-D numerical fluid dynamic models with varying plume excess temperatures and melt ...
  • Bjarnason, Ingi Þorleifur; Menke, William; Flóvenz, Ólafur G.; Caress, David (American Geophysical Union (AGU), 1993-04-10)
    The 170 km South Iceland Seismic Tomography (SIST) profile extends from the west and across the Mid‐Atlantic Ridge spreading center in the Western Volcanic Zone and continues obliquely through the transform zone (the South Iceland Seismic Zone) to the ...