Near-distance seismological monitoring of the Lansjaerv neotectonic fault region. Pt. 2: 1988

During five months in 1988, a mobile seismic network (six stations) was operated near the Lansjaerv neotectonic fault in Swedish Lapland. This was a continuation of an investigation in the same area in 1987. Some 30 local earthquakes were recorded, 18 of which have been located. A restrained focal depth has been obtained for six of these, and the depths range from 5 to 12 km. There is no clear spatial association of the earthquakes with the lateglacial fault segments, but many epicentres lie close to an older fault with the trend perpendicular to that of the lateglacial fault segments. Seismic moments from 1010 to 1012 Nm, fault radii 30-100 m, average dislocations 0.03-3 mm and stress drops 0.01-4 MPa have been computed from Sg-wave amplitude spectra. Focal mechanisms are not well constrained due to the small number of stations, and their tectonic interpretation is uncertain. (orig.)