| Summary: | Iceland is located on the Mid-Atlantic Ridge and is the surface exposure of the ridge system on land. The influence of the plume has been shown to reach towards the south at least as far as the Bight Transform Fault. The ridge system in Iceland has also been evolving spatially and temporally during the life time of Iceland. One of the best documented and understood mechanisms, where by plate boundaries evolve, is the propagating rift mechanism. Two such areas are studied in the dissertation; Eyjafjallajökull volcano in South Iceland and the area between the Bight-Transform Fault and 80 km south of it. These two areas are both located in front of the advancing limb of a propagating rift. Two papers focus on the Eyjafjallajökull volcano area. In the first paper the velocity structure of the volcano is presented. A fairly new method is used where long-time series of small surface waves are used as a source for tomography. The signal source of the method is the ambient noise, originating in the oceans. If such persistent signal is observed over long enough time and then cross-correlated between two seismic stations, a signal emerges that contains information on the path between the two receivers. Using data from a 7 month long period from stations located around the volcano, ambient seismic tomography was possible around Eyjafjallajökull. Reliable phase dispersion curves were obtained between 1-7 s and sensitivity kernels showed resolution down to 10 kilometers depth. The results show two high-velocity zones elongated E-W on either side of caldera. In between a zone of relatively lower-velocity is observed. The lower-velocity zone coincides with an inferred magma pathway under the volcano as observed from earthquakes in the 2010 Eyjafjallajökull volcano eruption. The higher-velocity zones are interpreted as zones of intrusive rocks. The second paper on Eyjafjallajökull focuses on the tremor observed during the 2010 eruption. Tremor can be located in several different ways, e.g. if the source is isotropic a simple ...
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