Färoe‐Iceland Ridge Experiment 2. Crustal structure of the Krafla central volcano

Brandsdóttír, Bryndís; Menke, William; Einarsson, Páll; White, R. S.; Staples, Robert K.

doi:10.1029/96jb03799

Cited by 149 publications

(150 citation statements)

References 39 publications

Supporting

Mentioning

134

Contrasting

Order By: Relevance

“…2e). A low seismic velocity anomaly and shear wave attenuation at 3-5 km depth has been interpreted as a shallow magma chamber 36 . It is located within a high velocity 'chimney' -probably a complex of intrusions -extending from the base of the crust.…”

Section: Subaerial Rifting Episodes In the Modern Eramentioning

confidence: 99%

Geophysical constraints on the dynamics of spreading centres from rifting episodes on land

et al. 2012

Self Cite

View full text Add to dashboard Cite

Most of the Earth's crust is created along 60,000 km of mid-ocean ridge system. Here, tectonic plates spread apart and, in doing so, gradually build up stress. This stress is released during rifting episodes, when bursts of magmatic activity lead to the injection of vertical sheets of magma -termed dykes -into the crust. Only 2% of the global mid-ocean ridge system is above sea level, so making direct observations of the rifting process is difficult. However, geodetic and seismic observations exist from spreading centres in Afar (East Africa) and Iceland that are exposed at the land surface. Rifting episodes are rare, but the few that have been well observed at these sites have operated with remarkably similar mechanisms. Specifically, magma is supplied to the crust in an intermittent manner, and is stored at multiple positions and depths. It then laterally intrudes in dykes within the brittle upper crust. Depending on the availability of magma, multiple magma centres can interact during one rifting episode. If we are to forecast large eruptions at spreading centres, rifting-cycle models will need to fully incorporate realistic crust and mantle properties, as well as the dynamic transport of magma.

show abstract

Section: Subaerial Rifting Episodes In the Modern Eramentioning

confidence: 99%

Geophysical constraints on the dynamics of spreading centres from rifting episodes on land

et al. 2012

Self Cite

View full text Add to dashboard Cite

show abstract

“…There is a shallow crustal magma reservoir with an upper boundary at a depth of approximately 3 km, near the center of inflation in the caldera (Einarsson, 1978). This magma chamber is smaller than the caldera, about 2-3 km in the N-S direction and 8-10 km in the E-W direction, with a thickness of 0.75-1.8 km (Brandsdottir et al, 1997). Geodetic measurements support the existence of a shallow magma chamber at a depth of 3 km within the caldera and have been used to argue for the existence of multiple magma reservoirs at depth (Tryggvason, 1986).…”

Section: Introductionmentioning

confidence: 99%

“…Figure 2a shows the epicenters of seismic events located from July 5th to August 11th and Figure 2b shows the depth distribution of some selected events along E-W and N-S cross-sections respectively. The velocity model used in the locating is from Brandsdottir et al (1997). Although these are preliminary locations, it is apparent that epicenters roughly align along the E-W direction, while hypocenters are shallow around the injection well.…”

Section: Introductionmentioning

confidence: 99%

Seismic imaging of the geothermal field at Krafla, Iceland using shear-wave splitting

Tang

Rial

Lees

2008

Journal of Volcanology and Geothermal Research

View full text Add to dashboard Cite

During the summer of 2004 we recorded the seismicity at the Krafla geothermal field for forty days with an array of twenty PASSCAL L-28 4.5-Hz sensors. The Krafla field is located approximately 60 km East of Akureyri in northern Iceland. The array covered an area approximately 5 km N-S by 4 km E-W. The field area is located on Holocene lava flows on the Mid-Atlantic Ridge. The array recorded approximately 5 micro-earthquakes per day at a sampling rate of 500 Hz. This high sampling rate is required to exploit newly developed theories on the frequency-dependence of shear-wave splitting (SWS). During the experiment, the injection well was stopped for ten days to study the response of the subsurface crack system to changes in water pressure. SWS is an exploration method based on the analyses of polarizations and time delays of shear waves that have been distorted by the anisotropy of the medium through which the seismic waves have propagated. Epicenters roughly align along the E-W direction, while hypocenters are shallow around the injection well and appear to be related to the on-going injection. Observations of SWS at Krafla have provided evidence for at least two major crack systems oriented approximately N-S and E-W. This last, rather unexpected direction is consistent with results from a simultaneous MT (magneto-telluric) survey. Further SWS study will lead to a more detailed understanding of the fracture locations, sizes, and orientations in the geothermal field.

show abstract

“…Controlled source experiments on Iceland have revealed Vp/Vsratios in oceanic layer 3 in the range 1.75e1.80 (Bjarnason et al, 1993;Brandsdottir et al, 1997;Staples et al, 1997;Darbyshire et al, 1998;Menke et al, 1998). These values are consistent with gabbro well below the solidus (Kampfmann and Berckhemer, 1985).…”

Section: Icelandic Type Oceanic Crustmentioning

confidence: 99%

Vp/Vs-ratios and anisotropy on the northern Jan Mayen Ridge, North Atlantic, determined from ocean bottom seismic data

et al. 2015

View full text Add to dashboard Cite

a b s t r a c tIn order to gain insight into the lithology and crustal evolution of the northern Jan Mayen Ridge, North Atlantic, the horizontal components of an Ocean Bottom Seismometer (OBS) dataset were analyzed with regard to Vp/Vs-modeling and seismic anisotropy. The modeling suggests that the northernmost part of the ridge consists of Icelandic type oceanic crust, bordered to the north by anomalously thick oceanic crust formed at the Mohns spreading ridge. The modeled Vp/Vs-ratios suggest variations in gabbroic composition and present-day temperatures in the area. Anisotropy analysis reveals a fast S-wave component along the Jan Mayen Ridge. This pattern of anisotropy is most readily interpreted as dikes intruded along the ridge, suggesting that the magmatism can be related to the development of a leaky transform since Early Oligocene.

show abstract

Färoe‐Iceland Ridge Experiment 2. Crustal structure of the Krafla central volcano

Abstract: The high-velocity dome, in our view, represents crust generated in and around the magma chamber, which has subsequently been advected to greater depths.

Cited by 149 publications

References 39 publications

Geophysical constraints on the dynamics of spreading centres from rifting episodes on land

Geophysical constraints on the dynamics of spreading centres from rifting episodes on land

Seismic imaging of the geothermal field at Krafla, Iceland using shear-wave splitting

Vp/Vs-ratios and anisotropy on the northern Jan Mayen Ridge, North Atlantic, determined from ocean bottom seismic data

Contact Info

Product

Resources

About