Location

Arlington, Virginia

Session Start Date

8-11-2008

Session End Date

8-16-2008

Abstract

Analysis of seismic site effects is still an open issue within projects that deal with the reduction of seismic risk. In the absence of surface and borehole arrays measurements, the main methodological approach consists of the individuation and the consequent appraisal of the surface effects in presence of “an expected” earthquake, through integrated geological, geomorphological, geological-technical, geophysical multidisciplinary surveys and by the use of numerical modelling. In historically densely populated urban areas, it is possible to verify if the calculated accelerations can be, at least qualitatively, correlated to the level of damage to buildings. However, there are frequent cases in which meaningful incongruences between modelling results and macroseismic effects are found. In particular, this note shows the case of Piancastagnaio (Central Italy), a small town in which an earthquake occurred in 2000 with a local magnitude ML = 3.6. In some buildings, constructed in the 1920's with earthquake-proof criteria for the times, this earthquake caused cracks justified only with intensities of VIII-IX degree of the EMS scale. The results of the analysis, carried out in compliance of the new Italian (D.M. dated 14.09.05, O.P.C.M. 3274 dated 20.03.03 and followings) and European (Eurocode8 dated 2003) seismic code and which classify the subsoil on the basis of the Vs30 values, do not justify such strong anomalous amplifications. With this work, the authors attempt an explanation of this kind of phenomenon and identify failure mechanisms as the cause of the identified local effects.

Department(s)

Civil, Architectural and Environmental Engineering

Appears In

International Conference on Case Histories in Geotechnical Engineering

Meeting Name

Sixth Conference

Publisher

Missouri University of Science and Technology

Publication Date

8-11-2008

Document Version

Final Version

Rights

© 2008 Missouri University of Science and Technology, All rights reserved.

Document Type

Article - Conference proceedings

File Type

text

Language

English

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Aug 11th, 12:00 AM Aug 16th, 12:00 AM

Seismic Site Effects in the Faulted Piancastagnaio Area (Italy): An Explanation Attempt

Arlington, Virginia

Analysis of seismic site effects is still an open issue within projects that deal with the reduction of seismic risk. In the absence of surface and borehole arrays measurements, the main methodological approach consists of the individuation and the consequent appraisal of the surface effects in presence of “an expected” earthquake, through integrated geological, geomorphological, geological-technical, geophysical multidisciplinary surveys and by the use of numerical modelling. In historically densely populated urban areas, it is possible to verify if the calculated accelerations can be, at least qualitatively, correlated to the level of damage to buildings. However, there are frequent cases in which meaningful incongruences between modelling results and macroseismic effects are found. In particular, this note shows the case of Piancastagnaio (Central Italy), a small town in which an earthquake occurred in 2000 with a local magnitude ML = 3.6. In some buildings, constructed in the 1920's with earthquake-proof criteria for the times, this earthquake caused cracks justified only with intensities of VIII-IX degree of the EMS scale. The results of the analysis, carried out in compliance of the new Italian (D.M. dated 14.09.05, O.P.C.M. 3274 dated 20.03.03 and followings) and European (Eurocode8 dated 2003) seismic code and which classify the subsoil on the basis of the Vs30 values, do not justify such strong anomalous amplifications. With this work, the authors attempt an explanation of this kind of phenomenon and identify failure mechanisms as the cause of the identified local effects.