Further information on the macroseismic field in the Balkan area
Tóm tắt
Papazachos and Papaioannou (1997) (called PP97 hereinafter) studied the macroseismic field in the Balkan area (Greece, Albania, former Yugoslavia, Bulgaria and western Turkey) with the purpose of deriving attenuation and scaling relations useful for seismic hazard assessment and study of historical earthquakes. In his comment, Trifunac suggests that our analysis might exhibit certain bias for all countries except Greece due to problems mainly associated with the database (completeness, etc.), conversion of local intensity scales used in the Balkan countries, as well as to the local variations of the attenuation relation due to the variation of the geotectonic environment in this area. Specifically, his most important comments can be summarized as follows: a) The large participation of Greek data probably biased the scaling relations proposed in the study. b) The conversion relations used between local macroseismic scales are less accurate than their proposed such relations. c) The variation of attenuation (geometrical and anelastic) in different regions of the study area is important and local relations (instead of the proposed single relation) should be determined for seismic hazard assessment. In the following, we study in detail each of these possible bias sources. Additional work on the macroseismic field of the Balkan area shows that none of the previously described factors, suggested by Trifunac, introduces bias in the results presented by PP97. Specifically, it is shown that the database used by PP97 fulfills the basic requirements for a reliable determinations of attenuation and scaling relations proper for seismic hazard assessment in all five countries of this area. Evidence is presented that no strong geographical variation of the attenuation of macroseismic intensities of shallow earthquakes is observed. Relations between local version of intensity scales suggested by Shebalin et al. (1974) are shown to be reliable. Finally, it is demonstrated that national practices for estimation of macroseismic intensities may affect the results of seismic hazard assessment but proper formulation can be applied (PP97) which allows to take into account such differences in national practices. This formulation allows also to introduce and correct for anisotropic radiation at the seismic source as well as the incorporation of site effects.
Tài liệu tham khảo
Ambraseys, N. N., 1985, Intensity-attenuation and magnitudeintensity relations for northwest European earthquakes, Earthq. Eng. and Struct. Dyn. 13, 1–29.
Anderson, J. G., 1978, On attenuation of modified Mercalli intensity with distance in the United States, Bull. Seismol. Soc. Am. 68, 1147–1179.
Cornell, C. A., 1968, Engineering seismic risk analysis, Bull. Seism. Soc. Am. 58, 1503–1606.
Dahle, A., Bungum, H. and Kramme, L. B., 1990, Attenuation models inferred from intraplate earthquake recordings, Earthq. Eng. and Str. Dyn. 19, 1125–1141.
Ewing, W. M., Jardetzky, W. S. and Press, F., 1957, Elastic waves in layered media, McGraw-Hill, New York, 374 pp.
Gupta, I. N. and Nuttli, O. W., 1976, Spatial attenuation of intensities for central U.S. earthquakes, Bull. Seismol. Soc. Am. 66, 743–751.
Hashida, T. and Shimazaki, K., 1984, Determination of seismic attenuation structure and source strength by inversion of seismic intensity data: method and numerical experiment, J. Phys. Earth. 29, 299–316.
Jackson, J., 1994, Active tectonics of the Aegean region, Ann. Rev. Earth Planet. Sci. 22, 239–271.
Koliopoulos, P., Klimis, N. and Margaris, V., 1997, Spectral and energy strong motion characteristics in Greece, 29th Gen. Ass. of IASPEI, 18–28 August 1997, Abstract Vol., Thessaloniki, Greece, 38 pp.
Kovachev, S. A., Kuzin, I. P., Shoda, O. Yu. and Soloviev, S. L., 1991, Attenuation of S-waves in the lithosphere of the sea of Crete according to OBS observations, Phys. Earth. Planet. Int. 69, 101–111.
Margaris, V. N., 1994, Azimuthal dependence of the seismic waves and its influence on the seismic hazard assessment in the area of Greece. PhD Thesis, Univ. Thessaloniki, 324 pp. (in Greek, with an English abstract).
McGuire, R. K., 1976, FORTRAN computer program for seismic risk analysis, Open-File Rep. 77, U.S. Geol. Survey, 90 pp.
McKenzie, D., 1978, Active tectonics of the Alpine-Himalayan belt: the Aegean Sea and surrounding regions, Geophys., J.R. Astron. Soc. 55, 217–254.
Papaioannou, Ch. A. and Papazachos, B. C., 1998, Time independent and time dependent seismic hazard in Greece based on seismogenic sources, Bull. Seism. Soc. Am. (submitted).
Papazachos, B. C. and Papazachou, C. B., 1997, The earthquakes of Greece. Editions Ziti, Thessaloniki, 304 pp.
Papazachos, B. C., Comninakis, P. E. and Drakopoulos, J. C., 1966, Preliminary results of an investigation of crustal structure in southeastern Europe, Bull. Seism. Soc. Am. 56, 1241–1268.
Papazachos, C. B., 1992, Anisotropic radiation modeling of macroseismic intensities for estimation of attenuation structure of the upper crust in Greece, Pure and Appl. Geophys. 138, 445–469.
Papazachos, C. B. and Papaioannou, Ch. A., 1977, The macroseismic field of the Balkan area, J. Seismology 1, 181–201.
Shebalin, N. V., Karnik, V. and Hadzievski, O., 1974, Catalogue of Earthquakes, UNDP/ UNESCO Survey of Seismicity of the Balkan Region, Skopje, Yugoslavia.
Theodulidis, N., 1991, A contribution to the study of strong ground motion in Greece (in Greek), PhD Thesis, University of Thessaloniki, Greece, 500 pp.
Todorovska, M. I., 1994, Effects of earthquake source parameters on uniform probability response spectra, Proc. 10th European Conf. Earthquake Engineering, Vol. 4, Balkema, Rotterdam, 1995, pp. 2579–2584.
Todorovska, M. I., Paskaleva, I. and Glavcheva, R., 1994, Earthquake source parameters for seismic hazard assessment: examples in Bulgaria, Proc. 10th European Conf. Earthquake Engineering, Vol. 4, Balkema, Rotterdam, 1995, pp. 2573–2578.
Trifunac, M. D., 1977, An instrumental comparison of the Modified Mercalli (MMI) and Medvedev-Karnik-Sponheuer (MKS) Intensity Scales, Proc. Sixth World Conf. on Earthquake Engineering, 1, New Delhi, India, pp. 715–720.
Trifunac, M. D. and Brady, A. G., 1975, On the correlation of seismic intensity scales with peaks of recorded strong ground motion, Bull. Seism. Soc. Am. 65, 139–162.
Trifunac, M. D. and Zivcic, M., 1991, A note on instrumental comparison of the Modified Mercalli Intensity (MMI) in the western United States and the Mercalli-Cancani-Sieberg (MCS) intensity in Yugoslavia, European Earthquake Engineering V (1), 22–26.
Trifunac, M. D., Lee, V. W., Cao, H. and Todorovska, M. I., 1988, Attenuation of seismic intensity in the Balkan countries. Dept. of Civil Eng. Rep. No. 88-01, Univ. Southern California, Los Angeles, California.