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| Titel |
Probabilistic seismic hazard in terms of intensities for Bulgaria and Romania – updated hazard maps |
| VerfasserIn |
G. Leydecker, H. Busche, K.-P. Bonjer, T. Schmitt, D. Kaiser, S. Simeonova, D. Solakov, L. Ardeleanu |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1561-8633
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| Digitales Dokument |
URL |
| Erschienen |
In: Natural Hazards and Earth System Science ; 8, no. 6 ; Nr. 8, no. 6 (2008-12-16), S.1431-1439 |
| Datensatznummer |
250005914
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| Publikation (Nr.) |
 copernicus.org/nhess-8-1431-2008.pdf |
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| Zusammenfassung |
Since 2007 Bulgaria and Romania are members of the
European Union. All member states have to introduce the European earthquake
building code EUROCODE 8 (EC 8) in the coming years. Therefore, new seismic
hazard maps have to be calculated according to the recommendations in EC 8.
Here the authors present a novel approach to compute such hazard maps. We
prefer to use the macroseismic intensity as hazard parameter because of two
reasons:
- The irregular azimuthal attenuation pattern of the Vrancea intermediate
depth earthquakes can be advantageously taken into account by using detailed
macroseismic maps.
- The intensity is directly related to the degree of damage and is the
original information in the historical earthquake catalogues.
The main base of our probabilistic analysis is the earthquake catalogue for
SE-Europe (Shebalin et al., 1998) in combination with national and regional
catalogues. Fore- and aftershocks were removed. Seismic source zones inside
an area of about 200 km around Romania and Bulgaria were defined based on
seismicity, neotectonics and geological development. For each seismic source
the intensity-frequency relation was calculated and a maximum possible
earthquake as well as a seismogenic depth was estimated. An appropriate
attenuation law was assumed. To cope with the irregular isoseismals of the
Vrancea intermediate depth earthquakes, a factor Ω was included in
the macroseismic attenuation law.
Using detailed macroseismic maps of three strong intermediate depth
earthquakes, Ω was calculated for each observation. Strong local
variations of Ω are avoided by averaging within grid cells of 0.5
degree in longitude and 0.25 degree in latitude.
The contributions of all seismic sources, the crustal normal depth source
zones and the Vrancea intermediate depth zone, were summed up and the annual
probability of exceedance was calculated. The contribution of the Vrancea
intermediate depth zone to each grid point was computed with the
corresponding representative Ω of this point; a seismogenic depth of
120 km has been assumed.
Each final seismic hazard map is a combination of two maps, the one for
normal depth source zones and the one for the Vrancea intermediate depth
zone. This is illustrated for a recurrence period of 475 years. Additional
hazard maps were calculated for different recurrence periods. |
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