HR: 1330h
AN: T52A-0249    [PDF]
TI: Detailed Stress Analysis of the Tj\"{o}rnes Fracture Zone in Northern Iceland, Using Microearthquakes.
AU: * Lund, B
EM: bjorn.lund@geo.uu.se
AF: Dep. of Eart Sciences, Uppsala University, Villav\"{a}gen 16, Uppsala, 752 36 Sweden
AU: Slunga, R
EM: slunga@geofys.uu.se
AF: Dep. of Eart Sciences, Uppsala University, Villav\"{a}gen 16, Uppsala, 752 36 Sweden
AU: B\"{o}dvarsson, R
EM: reynir.bodvarsson@geo.uu.se
AF: Dep. of Eart Sciences, Uppsala University, Villav\"{a}gen 16, Uppsala, 752 36 Sweden
AB: The Tj\"{o}rnes fracture zone in northern Iceland is an oblique, right-lateral transform zone connecting the off-shore Kolbeinsey Ridge to the west with the Icelandic Northern Rift zone to the west. Seismicity is mostly confined to two major zones, the Grimsey lineament to the north and the Husavik-Flatey fault to the south. The Husavik-Flatey fault is an old, well established strike-slip fault whereas the Grimsey lineament is considered to be the early stages of the formation of a new major fault. This study presents a detailed mapping of the state of stress in the Tj\"{o}rnes fracture zone using inversion of large numbers of microearthquake focal mechanisms. We show significant variations in the direction of the stress field along strike of the Husavik-Flatey fault and also in the Grimsey lineament. These variations are interpreted in terms of plate boundary deformation. We apply two different methods of stress inversion, one of which is sensitive to the strength of the fault system, and present an analysis of the results in terms of relative fault strength.
DE: 7230 Seismicity and seismotectonics
DE: 8164 Stresses--crust and lithosphere
SC: Tectonophysics [T]
MN: 2003 Fall Meeting