| Abstract: | A temporary network of microearthquake seismographs deployed in the northern part of Svalbard recorded numerous earthquakes during the summer of 1982. Most of the earthquakes occurred in concentrated zones in restricted portions of three fault complexes in central Nordaustlandet, but minor activity also occurred to the east and west of these complexes. Within the uncertainty of the epicentral locations, most earthquakes which occurred on land in regions not covered by glaciers could be associated with segments of mapped faults. There are numerous fault segments and even entire faults, however, along which no recorded earthquake occurred. The concentrated spatial locations of these earthquakes along preferred portions of mapped faults, and the absence of throughgoing lines of activity, suggest that these are intraplate earthquakes occurring along existing faults in response to an applied stress field. Composite fault-plane solutions for the three most active regions each include one nodal-plane which can be associated, at least roughly, with a trend of seismicity and trend of a mapped fault. The directions of greatest principle stress for the three fault plane solutions vary between N90°W and N55°W, directions which agree approximately with maximum stress directions determined for a region about 200 km to the south. The consistency of the directions of maximum principle stress obtained for earthquakes throughout a broad region of Svalbard suggests that the earthquakes there occur in response to a stress field which is of plate tectonic origin. |
