On the Observed Intensity Filtering in the Anisotropic Distribution Modelling of Macroseismic Intensity

Termini, D.; Teramo, A.; Tuvè, Tiziana; Bottari, Antonio

doi:10.1007/s00024-004-2632-0

Cited by 11 publications

(1 citation statement)

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“…It is widely recognised that the distribution of intensity and the inferred attenuation coefficients are strongly influenced by the different mechanical properties of geological substrates and outcrops (Trifunac 1990;Lee and Manic 1994;Albarello and Mucciarello 2002;Cubellis and Marturano 2002;Silveira et al 2003;Mucciarelli et al 2000Mucciarelli et al , 2004Termini et al 2005). Moreover, based on macroseismic data, several studies have proposed seismic zoning of some cities, comparing data of historical and recent earthquakes with surface geology and active tectonic structures.…”

Section: Filtering the Amplification Effectsmentioning

confidence: 99%

The catastrophic 1883 earthquake at the island of Ischia (southern Italy): macroseismic data and the role of geological conditions

2009

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This article presents the results of a detailed study of the effects of the 1883 earthquake, which occurred at the island of Ischia (Gulf of Naples) and produced the total destruction of buildings in the epicentral area (Casamicciola town). Despite the moderate magnitude, this event was characterised by very high intensities (I max = XI degree MCS) mainly due to the shallow depth of the source. The study of the earthquake shows that the intensities, which decreased rapidly with distance, were affected by source directivity, according to the causative fault geometry and tectonic structures, while local amplification of damage was observed where soft soils outcrop. The attenuation of seismic intensity with distance was evaluated using the well-known relation of intensity versus epicentral distance (Blake's method). The diverse gradients of attenuation, observed in different directions, were ascribed to the various geological features of the shallow crust of the island. In order to evaluate the role of geology in the damage level, we computed different attenuation models for stiff and soft soils outcropping on the island. A systematic local amplification of about 1 MCS degree associated to the presence of reworked tuffs was obtained. This study also shows the influence of geological conditions on the evaluation of macroseismic data and supplies useful elements to derive a predictive map of potential site effects.

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