Completeness of earthquake catalogues is a necessary condition for seismic hazard assessment sinc... more Completeness of earthquake catalogues is a necessary condition for seismic hazard assessment since they are the base for the determination of a and b values of the Gutenberg-Richter relation. A new composite catalogue for Austria has been created based on data from four different catalogues of earthquakes in Austria (ZAMG, 2009; ACORN, 2004; Van Gils & Leydecker, 1991; Shebalin et
In the framework of site evaluation/re-evaluation procedures for nuclear power plants and other n... more In the framework of site evaluation/re-evaluation procedures for nuclear power plants and other nuclear installations, this publication aims at encouraging and supporting Member States, especially from newcomer countries, to include paleoseismic investigations into the geologic database. In fact, paleoseismology is not just a crucial discipline for Fault Displacement Hazard Assessment (FDHA) but also an indispensable tool for Seismic Hazard Assessment (SHA), as recommended in the reference IAEA Safety Guide (IAEA SSG-9 [1]). Within this scope, this document provides an updated review of the state of the art of paleoseismology, integrated with practical recommendations addressed to Member States, aiming to emphasize the value of earthquake geology studies for nuclear safety.
ABSTRACT Subsidence of the Köflach-Voitsberg Basin was related to NE-directed extension and to th... more ABSTRACT Subsidence of the Köflach-Voitsberg Basin was related to NE-directed extension and to the formation of shallow (half)grabens. In the Oberdorf area extension created shallow depressions which controlled the local drainage pattern. Extensional faulting occurred during the incipient lateral movement of the Styrian crustal wedge between the Mur-Mürz- and the Lavanttal faults. The Early Miocene lignite-bearing Köflach-Voitsberg Formation originated in a marginal fluvial environment with floodplain- and floodbasin sediments alternating with crevasse splay deposits and channel fillings. Palaeosols with characteristics of temporarily waterlogged soils occur frequently. The circa 30 m thick lignite seam consists mainly of xylo-detritic coal. Coal-petrographic data show that it originated in a relatively wet low-moor with relatively high pH-values. The lignite-bearing sequence in the Oberdorf opencast mine is extremely rich in fossil plant remains (diaspores, leaves and palynomorphs) at almost all levels. Woody genera are dominant. Herbaceous elements reflecting forest floor or reed-like facies and aquatic plants are well represented in the pollen record. In the diaspore record, they generally occur rarely and are species poor. With the exception of some ferns leaf remains of herbs are lacking . The palaeoclimatic conditions are estimated at 14–17°C mean annual temperature and 1000–2000 mm mean annual precipitation. Two vertebrate faunas from the hanging wall of the eastern sub-basin are very rich in amphibians, lizards, snakes and mammals. More than 80 vertebrate species are recorded, almost exclusively from isolated teeth and inarticulated bones. This kind of selection and concentration of fossils is interpreted as a result of taphonomic processes. Although some were omnivorous or insectivorous, most of the mammals were plant eaters using the forest environments for living and their rich supply of fruits, berries, seeds, leaves and roots for food. The majority of the small vertebrates is thought to have lived in burrows underground or in bushes and under rotting logs, while the flying squirrels needed high trees for their activities.
Research on neotectonics and related seismicity has hitherto been mostly focused on active plate ... more Research on neotectonics and related seismicity has hitherto been mostly focused on active plate boundaries that are characterized by generally high levels of earthquake activity. Current seismic hazard estimates for intraplate domains are mainly based on probabilistic analyses of historical and instrumental earthquake catalogues. The accuracy of such hazard estimates is limited by the fact that available catalogues are restricted to a few hundred years, which, on geological time scales, is insignificant and not suitable for the assessment of tectonic processes controlling the observed earthquake activity. More reliable hazard prediction requires access to high quality data sets covering a geologically significant time span in order to obtain a better understanding of processes controlling ongoing intraplate deformation. The Alpine Orogen and the intraplate sedimentary basins and rifts in its northern foreland are associated with a much higher level of neotectonic activity than hitherto assumed. Seismicity and stress indicator data, combined with geodetic and geomorphologic observations, demonstrate that deformation of the Northern Alpine foreland is still ongoing and will continue in the future. This has major implications for the assessment of natural hazards and the environmental degradation potential of this densely populated area. We examine relationships between deeper lithospheric processes, neotectonics and surface processes in the northern Alpine Foreland, and their implications for tectonically induced topography.
Completeness of earthquake catalogues is a necessary condition for seismic hazard assessment sinc... more Completeness of earthquake catalogues is a necessary condition for seismic hazard assessment since they are the base for the determination of a and b values of the Gutenberg-Richter relation. A new composite catalogue for Austria has been created based on data from four different catalogues of earthquakes in Austria (ZAMG, 2009; ACORN, 2004; Van Gils & Leydecker, 1991; Shebalin et al., 1998) including for the first time also data from surrounding regions such as the Vienna Basin outside Austria and a buffer region 100km outside the boundary of the Austria and Vienna basin. The used earthquake catalogues cover different record length with a first entry in 1048 AD. A reliable estimate of the a and b parameters of the Gutenberg-Richter Relation from this newly compiled dataset can be only given, if the new catalogue is checked for completeness. We determined the completeness intensity (Ic) and the completeness periods for the composite catalogue following the method described by Stepp (1972). This method supposes that the earthquake occurrences are Poisson-distributed and investigates (i) the minimum observation interval required to reach reliable estimates of mean recurrence periods, (ii) the time interval for which the catalogues may be regarded complete. Both intervals are functions of the intensity class. Ic is the smallest intensity above which every earthquake was recorded for a given time interval. The completeness period is the time interval in which the catalogue is complete for a given intensity range. As most of the catalogue's records are pre-instrumental data, this completeness check was performed on intensity data avoiding ambiguities arising from intensity-magnitude conversion. In a second step, we repeated the completeness check, but this time based on magnitudes in order to determine the influences of various magnitude conversions. For pre-instrumental events, we converted intensities into magnitudes using published intensity-magnitude conversion formula for each country. In order to get the completeness periods for various magnitude ranges, the combined catalogue as well as each subcatalogue have been analyzed following the method of Stepp (1972). We can show that the new composite catalogue fulfills the critical minimum observation period for all intensity classes except IX and higher. A stable estimate of mean recurrence period of intensity IV is 80 years of homogeneous observations from 1900 to 1980 and for intensity V, the observation period is 120 years. A stable estimate of mean recurrence period for intensity VI is about 115 years and for intensity vii is 30 years. The homogeneous interval for maximum intensity VIII is 200 years. Maximum intensity IX earthquakes are not completely definitive for whole 962 years period. In addition, the analysis of each subcatalogue leads to similar results, except the ACORN catalogue. Therefore, the newly complied catalogue for Austria and surrounding areas is a suitable data base for seismic hazard assessment in Austria. References: ACORN, 2004, Catalogue of Earthquakes in the Region of the Alps - Western Carpathians - Bohemian Massif for the period from 1267 to 2004, Computer File, Vienna (Central Institute for Meteorology and Geodynamics, Department of Geophysics) - Brno (Institute of Physics of the Earth, University Brno). Van Gils, J.M. and G. Leydecker (1991): Catalogue of European earthquakes with intensities higher than 4. -- Commission of the European Communities - nuclear science and technology. 353 pp., 14 fig., 1 tab.- ISBN 92-826-2506-0, Catalogue number: CD-NA-13406-EN-C. Brussels - Luxembourg 1991. Shebalin, N. V., Leydecker, G., et al. (1998): Earthquake Catalogue for Central and Southeastern Europe 342 BC - 1990 AD. -- European Commission, Report No. ETNU CT 93 - 0087, Brussels. Stepp, J.C., 1972. Analysis of completeness of the earthquake sample in the Puget Sound area and its effect on statistical estimates of earthquake hazard. Proc. of the 1st Int. Conf. on Microzonazion, Seattle, vol. 2, pp. 897-910. ZAMG, 2009. Earthquake catalogue of felt earthquakes 1201 - 2009 A.D. (Austria). Computer File. Central Institute of Meteorology and Geodynamics (ZAMG), Vienna Austria.
Completeness of earthquake catalogues is a necessary condition for seismic hazard assessment sinc... more Completeness of earthquake catalogues is a necessary condition for seismic hazard assessment since they are the base for the determination of a and b values of the Gutenberg-Richter relation. A new composite catalogue for Austria has been created based on data from four different catalogues of earthquakes in Austria (ZAMG, 2009; ACORN, 2004; Van Gils & Leydecker, 1991; Shebalin et
In the framework of site evaluation/re-evaluation procedures for nuclear power plants and other n... more In the framework of site evaluation/re-evaluation procedures for nuclear power plants and other nuclear installations, this publication aims at encouraging and supporting Member States, especially from newcomer countries, to include paleoseismic investigations into the geologic database. In fact, paleoseismology is not just a crucial discipline for Fault Displacement Hazard Assessment (FDHA) but also an indispensable tool for Seismic Hazard Assessment (SHA), as recommended in the reference IAEA Safety Guide (IAEA SSG-9 [1]). Within this scope, this document provides an updated review of the state of the art of paleoseismology, integrated with practical recommendations addressed to Member States, aiming to emphasize the value of earthquake geology studies for nuclear safety.
ABSTRACT Subsidence of the Köflach-Voitsberg Basin was related to NE-directed extension and to th... more ABSTRACT Subsidence of the Köflach-Voitsberg Basin was related to NE-directed extension and to the formation of shallow (half)grabens. In the Oberdorf area extension created shallow depressions which controlled the local drainage pattern. Extensional faulting occurred during the incipient lateral movement of the Styrian crustal wedge between the Mur-Mürz- and the Lavanttal faults. The Early Miocene lignite-bearing Köflach-Voitsberg Formation originated in a marginal fluvial environment with floodplain- and floodbasin sediments alternating with crevasse splay deposits and channel fillings. Palaeosols with characteristics of temporarily waterlogged soils occur frequently. The circa 30 m thick lignite seam consists mainly of xylo-detritic coal. Coal-petrographic data show that it originated in a relatively wet low-moor with relatively high pH-values. The lignite-bearing sequence in the Oberdorf opencast mine is extremely rich in fossil plant remains (diaspores, leaves and palynomorphs) at almost all levels. Woody genera are dominant. Herbaceous elements reflecting forest floor or reed-like facies and aquatic plants are well represented in the pollen record. In the diaspore record, they generally occur rarely and are species poor. With the exception of some ferns leaf remains of herbs are lacking . The palaeoclimatic conditions are estimated at 14–17°C mean annual temperature and 1000–2000 mm mean annual precipitation. Two vertebrate faunas from the hanging wall of the eastern sub-basin are very rich in amphibians, lizards, snakes and mammals. More than 80 vertebrate species are recorded, almost exclusively from isolated teeth and inarticulated bones. This kind of selection and concentration of fossils is interpreted as a result of taphonomic processes. Although some were omnivorous or insectivorous, most of the mammals were plant eaters using the forest environments for living and their rich supply of fruits, berries, seeds, leaves and roots for food. The majority of the small vertebrates is thought to have lived in burrows underground or in bushes and under rotting logs, while the flying squirrels needed high trees for their activities.
Research on neotectonics and related seismicity has hitherto been mostly focused on active plate ... more Research on neotectonics and related seismicity has hitherto been mostly focused on active plate boundaries that are characterized by generally high levels of earthquake activity. Current seismic hazard estimates for intraplate domains are mainly based on probabilistic analyses of historical and instrumental earthquake catalogues. The accuracy of such hazard estimates is limited by the fact that available catalogues are restricted to a few hundred years, which, on geological time scales, is insignificant and not suitable for the assessment of tectonic processes controlling the observed earthquake activity. More reliable hazard prediction requires access to high quality data sets covering a geologically significant time span in order to obtain a better understanding of processes controlling ongoing intraplate deformation. The Alpine Orogen and the intraplate sedimentary basins and rifts in its northern foreland are associated with a much higher level of neotectonic activity than hitherto assumed. Seismicity and stress indicator data, combined with geodetic and geomorphologic observations, demonstrate that deformation of the Northern Alpine foreland is still ongoing and will continue in the future. This has major implications for the assessment of natural hazards and the environmental degradation potential of this densely populated area. We examine relationships between deeper lithospheric processes, neotectonics and surface processes in the northern Alpine Foreland, and their implications for tectonically induced topography.
Completeness of earthquake catalogues is a necessary condition for seismic hazard assessment sinc... more Completeness of earthquake catalogues is a necessary condition for seismic hazard assessment since they are the base for the determination of a and b values of the Gutenberg-Richter relation. A new composite catalogue for Austria has been created based on data from four different catalogues of earthquakes in Austria (ZAMG, 2009; ACORN, 2004; Van Gils & Leydecker, 1991; Shebalin et al., 1998) including for the first time also data from surrounding regions such as the Vienna Basin outside Austria and a buffer region 100km outside the boundary of the Austria and Vienna basin. The used earthquake catalogues cover different record length with a first entry in 1048 AD. A reliable estimate of the a and b parameters of the Gutenberg-Richter Relation from this newly compiled dataset can be only given, if the new catalogue is checked for completeness. We determined the completeness intensity (Ic) and the completeness periods for the composite catalogue following the method described by Stepp (1972). This method supposes that the earthquake occurrences are Poisson-distributed and investigates (i) the minimum observation interval required to reach reliable estimates of mean recurrence periods, (ii) the time interval for which the catalogues may be regarded complete. Both intervals are functions of the intensity class. Ic is the smallest intensity above which every earthquake was recorded for a given time interval. The completeness period is the time interval in which the catalogue is complete for a given intensity range. As most of the catalogue's records are pre-instrumental data, this completeness check was performed on intensity data avoiding ambiguities arising from intensity-magnitude conversion. In a second step, we repeated the completeness check, but this time based on magnitudes in order to determine the influences of various magnitude conversions. For pre-instrumental events, we converted intensities into magnitudes using published intensity-magnitude conversion formula for each country. In order to get the completeness periods for various magnitude ranges, the combined catalogue as well as each subcatalogue have been analyzed following the method of Stepp (1972). We can show that the new composite catalogue fulfills the critical minimum observation period for all intensity classes except IX and higher. A stable estimate of mean recurrence period of intensity IV is 80 years of homogeneous observations from 1900 to 1980 and for intensity V, the observation period is 120 years. A stable estimate of mean recurrence period for intensity VI is about 115 years and for intensity vii is 30 years. The homogeneous interval for maximum intensity VIII is 200 years. Maximum intensity IX earthquakes are not completely definitive for whole 962 years period. In addition, the analysis of each subcatalogue leads to similar results, except the ACORN catalogue. Therefore, the newly complied catalogue for Austria and surrounding areas is a suitable data base for seismic hazard assessment in Austria. References: ACORN, 2004, Catalogue of Earthquakes in the Region of the Alps - Western Carpathians - Bohemian Massif for the period from 1267 to 2004, Computer File, Vienna (Central Institute for Meteorology and Geodynamics, Department of Geophysics) - Brno (Institute of Physics of the Earth, University Brno). Van Gils, J.M. and G. Leydecker (1991): Catalogue of European earthquakes with intensities higher than 4. -- Commission of the European Communities - nuclear science and technology. 353 pp., 14 fig., 1 tab.- ISBN 92-826-2506-0, Catalogue number: CD-NA-13406-EN-C. Brussels - Luxembourg 1991. Shebalin, N. V., Leydecker, G., et al. (1998): Earthquake Catalogue for Central and Southeastern Europe 342 BC - 1990 AD. -- European Commission, Report No. ETNU CT 93 - 0087, Brussels. Stepp, J.C., 1972. Analysis of completeness of the earthquake sample in the Puget Sound area and its effect on statistical estimates of earthquake hazard. Proc. of the 1st Int. Conf. on Microzonazion, Seattle, vol. 2, pp. 897-910. ZAMG, 2009. Earthquake catalogue of felt earthquakes 1201 - 2009 A.D. (Austria). Computer File. Central Institute of Meteorology and Geodynamics (ZAMG), Vienna Austria.
Uploads
Papers by Decker Kurt