摘要:

Studies of seismic risk in Sweden indicate that there is coherence between the epicentres of earthquakes and the tectonics. On the basis of the existing seismic data and the tectonics, eleven seismo-tectonic zones are suggested for the Fennoscandian Shield. The correlation between the gravity data, the late glacial movements and the seismo-tectonic zones is found to be positive.

ISSN:0016-786X    

DOI:10.1080/11035897809452527

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

ISSN:0016-786X    

DOI:10.1080/11035897809452528

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

During the Middle Proterozoic orogenic period, the earlier structures of the Finnish bedrock underwent such intense deformation that also the later, differentiated, crustal movements, which were epeirogenic in nature, took place mainly along the deep fractures produced at this time. Recent seismicity, manifested by the latest deformation phase, is likewise associated with these crustal zones of weakness of ancient origin. An apparent, seismogenic, cause-and-effect relation is to be found in both the internal and external tectonics of the Fennoscandian Shield.

ISSN:0016-786X    

DOI:10.1080/11035897809452529

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

ISSN:0016-786X    

DOI:10.1080/11035897809452530

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

A tectonic-fracture map, covering southern Sweden, has been constructed on the basis of lineament analyses and described fracture patterns in the bedrock. Three types of lineaments have been used, namely, morphological, aerial-photographic and Landsat-satellite lineaments. The analysis has resulted in a division of the existing fracture pattern into three types. The Mylonite Zone, which subdivides the area into two blocks, is characterized by a fracture pattern of first-order magnitude. The fracture pattern east of the Mylonite Zone is distinguished by main tectonic orientations to the WNW, NW och N, while the area west of the Mylonite Zone has main orientations to the N, NE and ENE. These fractures are of second- and third-order magnitude.

ISSN:0016-786X    

DOI:10.1080/11035897809452531

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

ISSN:0016-786X    

DOI:10.1080/11035897809452532

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

Several fault-lines, presumably of late-glacial age, in northern Sweden are described. The amount of displacement in the dislocations may reach 25 m and the most extensive fault-line is about 150 km long. The faults were all developed in the Precambrian and they frequently coincide with older dislocation zones. The regional connection between the neotectonic structures and the Recent seismic pattern within the area is obvious. This indicates that the forces which produced the faulting are possibly still active.

ISSN:0016-786X    

DOI:10.1080/11035897809452533

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

ISSN:0016-786X    

DOI:10.1080/11035897809452534

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

The interpretation of low-altitude, aeromagnetic measurements from six areas (each 50 × 50 km) in the Precambrian of northern Sweden yields distinct sets of dislocations with main directions of −35°, 0° and 55°. These dislocations appear to be of transcurrent-fault type. The displacement for the −35° direction is mainly sinistral and vertical, and for the 55° direction exclusively dextral. The 0° direction shows displacement patterns that may be interpreted as exclusively vertical. The apparent, mean, lateral displacement is 400 m, with slight changes in different directions. The dislocations occur at preferred distances with a maximum at about 30 km. On a regional scale, the two main dislocation sets are parallel to the present, active, fracture zones, as indicated by recent seismic activity and mapped, post-glacial fault movements. It is concluded that the low-altitude aeromagnetic anomalies give very clear indications on a regional scale of dislocations and their displacement.

ISSN:0016-786X    

DOI:10.1080/11035897809452535

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

Studies within the Swedish Geodynamics Project of the Fennoscandian uplift have given a quite new picture of the uplift, viz. a total uplift of 830 m, a total forebulge subsidence of 170 m, isostatic peak rates of several hundred millimeters per year, a relaxation time of only 900 years, the existence of a low-viscosity asthenosphere, an uplift/subsidence ratio of 1:1 and a total volume of 0.7 million km3. The uplift was driven by two different mechanisms: a rapid adjustment of the asthenosphere and a “linear” uplift (=the present uplift) of uncertain origin. Geological and geodetic data agree perfectly well over the whole of Sweden south of the River Dalälven. The past and present uplifts exhibit many irregularities, most of which are linked to old fault lines and bedrock seams. The Kolmården area seems to have undergone oscillating crustal movements of fairly large amplitude. Faulting, fracturing and seismic activity are found to have occured frequently and to be linked to the peak rates of isostasy and changes in the rate of uplift. The recorded crustal movements and activities of the last 20 000 years are all expected to be repeated during the next 20000 years, indicating an unsafe geodynamic future. Predictions based only on data from the last hundred years are rejected.

ISSN:0016-786X    

DOI:10.1080/11035897809452536

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor