Fennoscandian earthquakes: Whole crustal rupturing related to postglacial rebound

Science

Volumn 274, Issue 5288, 1996, Pages 744-746

  Arvidsson, Ronald ^a,b  

^a UPPSALA UNIVERSITY   (Sweden)

^b HARVARD UNIVERSITY   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

ARTICLE; EARTHQUAKE; GEOLOGY; PRIORITY JOURNAL;

DEGLACIATION; EARTHQUAKE; POSTGLACIAL REBOUND; SEISMICITY;

EUROPE, FENNOSCANDIA;

EID: 0029659880     PISSN: 00368075     EISSN: None     Source Type: Journal    
DOI: 10.1126/science.274.5288.744     Document Type: Article

References (36)

1. R. Kujansuu, Geol. Surv. Finland Bull. 256, 1 (1964); J. Lundqvist and R. Lagerbäck, Geol. Fören. Stockholm Förh. 98, 45 (1976); O. Olesen, Nor. Geol. Tidsskr. 8, 107 (1988).
2. R. Kujansuu, Geol. Surv. Finland Bull. 256, 1 (1964); J. Lundqvist and R. Lagerbäck, Geol. Fören. Stockholm Förh. 98, 45 (1976); O. Olesen, Nor. Geol. Tidsskr. 8, 107 (1988).
3. R. Kujansuu, Geol. Surv. Finland Bull. 256, 1 (1964); J. Lundqvist and R. Lagerbäck, Geol. Fören. Stockholm Förh. 98, 45 (1976); O. Olesen, Nor. Geol. Tidsskr. 8, 107 (1988).
4. R. Sabadini, K. Lambeck, E. Boschi, Eds., Glacial Isostasy, Sea-Level and Mantle Rheology (Kluwer, Dordrecht, Netherlands, 1991).
5. R. Lagerbäck, Geol. Fören. Stockholm Förh. 112, 333 (1990); R. Lagerbäck, ibid. 100, 263 (1979).
6. R. Lagerbäck, Geol. Fören. Stockholm Förh. 112, 333 (1990); R. Lagerbäck, ibid. 100, 263 (1979).
7. P. A. Pirazzoli, in (2), pp. 259-269.
8. A. C. Johnston, Geophys. J. Int. 126, 314 (1996).
9. L. R. Sykes, Rev. Geophys. Space Phys. 16, 621 (1978); J. W. Dewey, D. P. Hill, W. L. Ellsworth, E. R. Engdahl, Geol. Soc. Am. Mem. 172, 541 (1989).
10. L. R. Sykes, Rev. Geophys. Space Phys. 16, 621 (1978); J. W. Dewey, D. P. Hill, W. L. Ellsworth, E. R. Engdahl, Geol. Soc. Am. Mem. 172, 541 (1989).
11. R. Arvidsson and O. Kulhanek, Geophys. J. Int. 116, 377 (1994).
12. W.-Y. Kim, E. Skordas, Y.-P. Zhou, O. Kulhanek, Swedish Nuclear Fuel Waste Manage. Tech. Rep. 88-23 (1988).
13. T. Ahjos and M. Uski, Tectonophysics 207, 1 (1992).
14. The area covered by earthquakes related to PGFs was defined by the length times the width. Total length covered by the PGFs is ∼500 km. Width, the distance from the fault, 10 km on the footwall side and 50 km on the hanging wall side, was based on mislocation uncertainty of 10 km [R. Arvidsson and R. Wahlström, Swedish Nuclear Fuel Waste Manage. Tech. Rep. 93-13 (1993)] and surface projection of a 45° dipping fault in a 40-km-deep crust. The area covered by postglacial earthquakes, about 6% of the area east of the dotted line in Fig. 1, contains 48 out of 99 earthquakes, of the investigated area. The statistical probability of this occurrence, estimated as a Poisson process, is almost zero.
15. R. Wahlström, S.-O. Linder, C. Holmquist, H.-E. Mårtensson, Swedish Nuclear Fuel Waste Manage. Tech. Rep. 89-01 (1989).
16. I located the events by a version of the Hypocenter program [B. R. E. Lienert, Inst. Solid Earth Physics, Univ. Bergen Tech. Rep. (1991)], which allows use of S and P arrival times, S-P times (when station clock time was not exact due to poor radio receiving conditions), and azimuths. The azimuths were determined by a maximum likelihood approach [R. G. Roberts and A. Christoffersson, Geophys. J. Int. 103, 55 (1990)]. The exactness of the locations was tested by determining locations from test explosions. The errors ranged from 0.7 to 6 km in the worst case (only three phases and one azimuth). On this basis and the number of recorded phases (out of 31 events, 25 had 5 to 12 phases and the rest 3 to 4 phases, and azimuths), I estimated the typical error to less than 1 km.
17. I located the events by a version of the Hypocenter program [B. R. E. Lienert, Inst. Solid Earth Physics, Univ. Bergen Tech. Rep. (1991)], which allows use of S and P arrival times, S-P times (when station clock time was not exact due to poor radio receiving conditions), and azimuths. The azimuths were determined by a maximum likelihood approach [R. G. Roberts and A. Christoffersson, Geophys. J. Int. 103, 55 (1990)]. The exactness of the locations was tested by determining locations from test explosions. The errors ranged from 0.7 to 6 km in the worst case (only three phases and one azimuth). On this basis and the number of recorded phases (out of 31 events, 25 had 5 to 12 phases and the rest 3 to 4 phases, and azimuths), I estimated the typical error to less than 1 km.
18. C. H. Scholz, The Mechanics of Earthquakes and Faulting (Cambridge Univ. Press, Cambridge, 1990).
19. L = 2.4, h = 34 km) at 66.42°N and 21.71°E recorded by mobile networks (12). The two focal mechanisms are, for event 5, strike = 30°, dip = 80°, rake = -34°, and for event 6, strike = 205°, dip = 70°, rake = 20°.
20. C. Lindholm, H. Bungum, M. Villagran, E. Hicks, Proceedings Workshop on Rock Stresses in the North Sea, Trondheim, Norway, 13 to 14 February 1995, pp. 77-91.
21. C. Talbot, Swedish Nuclear Fuel Waste Manage. Tech. Rep. 86-20 (1986); H. Henkel, ibid. Tech. Rep. 88-07 (1988).
22. C. Talbot, Swedish Nuclear Fuel Waste Manage. Tech. Rep. 86-20 (1986); H. Henkel, ibid. Tech. Rep. 88-07 (1988).
23. R. Muir Wood, ibid. Tech. Rep. 93-13 (1993).
24. S. Das and C. H. Scholz, Nature 305, 621 (1983).
25. W.-Y. Kim, O. Kulhanek, T. van Eck, R. Wahlström, Rep. 1-85, Seismological Department, Uppsala University (1985).
26. H. Bungum, A. Alsaker, L. B. Kvamme, R. A. Hansen, J. Geophys. Res. 96, 2249 (1991).
27. W.-P. Chen, Seismol. Res. Lett. 59, 263 (1988); R. Arvidsson, thesis, Uppsala University. Uppsala, Sweden (1991).
28. W.-P. Chen, Seismol. Res. Lett. 59, 263 (1988); R. Arvidsson, thesis, Uppsala University. Uppsala, Sweden (1991).
29. N. Balling, Tectonophysics 244, 13 (1995).
30. U. Luosto, ibid. 189, 19 (1991).
31. I. P. Parsons, J. F. Hall, G. A. Lyzenga, Bull. Seismol. Soc. Am. 78, 931 (1988).
32. Estimated fault dimensions [L and D determined from data in (1, 3, 4)]; Pärvie fault, L = 160 ± 10 km; W = 45 ± 15 km, if the dip varies between 90° and 40° and the seismogenic zone is between 30 and 40 km; displacement is based on averaging of surface measurements, D = 8 ± 2 m; Lansjärv PGF, L = 50 ± 5 km, W = 40 ± 10 km, D = 7 ± 2 m.
33. H. Kanamori and D. L. Anderson, Bull. Seismol. Soc. Am. 65, 1073 (1975).
34. S. Stein et al., in Earthquakes at North Atlantic Passive Margins: Neotectonics and Postglacial Rebound, S. Gregersen and P. W. Basham, Eds. (Kluwer, Dordrecht, Netherlands, (1989), pp. 231-259.
35. A. C. Johnston, in ibid., pp. 581-591.
36. I thank R. Roberts and A. Christoffersson for supplying the program for azimuth calculations and G. Ekström, O. Kulhanek, M. Nettles, and two anonymous reviewers for comments. This research was partially supported by the Swedish Natural Research Science Council through projects G-GU 3164-309,312 and the Swedish Foundation for International Cooperation in Research and Higher Education.