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| Titel |
Application of Environmental Seismic Intensity scale (ESI 2007) to Krn Mountains 1998 Mw = 5.6 earthquake (NW Slovenia) with emphasis on rockfalls |
| VerfasserIn |
A. Gosar |
| 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 ; 12, no. 5 ; Nr. 12, no. 5 (2012-05-24), S.1659-1670 |
| Datensatznummer |
250010828
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| Publikation (Nr.) |
 copernicus.org/nhess-12-1659-2012.pdf |
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| Zusammenfassung |
The 12 April 1998 Mw = 5.6 Krn Mountains earthquake with a maximum intensity of
VII–VIII on the EMS-98 scale caused extensive environmental effects in the
Julian Alps. The application of intensity scales based mainly on damage to
buildings was limited in the epicentral area, because it is a high mountain
area and thus very sparsely populated. On the other hand, the effects on the
natural environment were prominent and widespread. These facts and the
introduction of a new Environmental Seismic Intensity scale (ESI 2007)
motivated a research aimed to evaluate the applicability of ESI 2007 to this
event. All environmental effects were described, classified and evaluated by
a field survey, analysis of aerial images and analysis of macroseismic
questionnaires. These effects include rockfalls, landslides, secondary
ground cracks and hydrogeological effects. It was realized that only
rockfalls (78 were registered) are widespread enough to be used for
intensity assessment, together with the total size of affected area, which
is around 180 km2. Rockfalls were classified into five categories
according to their volume. The volumes of the two largest rockfalls were
quantitatively assessed by comparison of Digital Elevation Models to be
15 × 106 m3 and 3 × 106 m3. Distribution of very large,
large and medium size rockfalls has clearly defined an elliptical zone,
elongated parallel to the strike of the seismogenic fault, for which the
intensity VII–VIII was assessed. This isoseismal line was compared to the
tentative EMS-98 isoseism derived from damage-related macroseismic data. The
VII–VIII EMS-98 isoseism was defined by four points alone, but a similar
elongated shape was obtained. This isoseism is larger than the corresponding
ESI 2007 isoseism, but its size is strongly controlled by a single intensity
point lying quite far from others, at the location where local amplification
is likely.
The ESI 2007 scale has proved to be an effective tool for intensity
assessment in sparsely populated mountain regions not only for very strong,
but for moderate earthquakes as well. This study has shown that the
quantitative definition of rockfall size and frequency, which is diagnostic
for each intensity, is not very precise in ESI 2007, but this is
understandable since the rockfall size is related not only to the level of
shaking, but also depends highly on the vulnerability of rocky slopes. |
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