Critical considerations on the evaluation of macroseismic effects

E Lo Giudice E Lo Giudice,A Bottari A Bottari,M C Spadea M C Spadea

doi:10.4401/ag-4708

Abstract

The definition of some of the standards used for evaluating local effectsand optimizing the relative macroseismic procedures are criticallyconsidered, also from the different interpretative points of view to havecome out of the « Earthquake Catalogue » work group of the Italian GeodynamicsProjetc (PFG). Particular stress has been laid on the significanceand reliability of the main macroseismic parameters which dependmost directly on the investigative criteria used and on their ability tocharacterize efficiently the interaction of earthquakes and environment.Essentially, the analysis is of critical considerations and field-observations,the fruit of macroseismic investigations carried out prevalently inthe Calabro-Peloritan Arc region. The seismic intensity, the use of macroseismicscales, the investigatory criteria, the macroseismic field and its anomalies are the topics chosen for a study which — even if limited fromcertain aspects — it is hoped will stimulate further thought and evaluations.

Highlights

To characterize the seismicity of a region basically involves a good knowledge of its geology, tectonics and seismic phenomenology
In recent years aftera period of inactivity that can only in part be explained by the War, there has been in our country an increasing interest shown in the macroseismic study of historic and recent earthquakes
From a critical consideration of the criteria at the basis of an evaluation of the effects of an earthquake on people and their environment, it can be seen that apart from the difficulties and limitations inherent in macroseismic methodologies, some causes of error and/or ambiguity can be overcome by a judicious use of the MSK intensity scale

Summary

INTRODUCTION

To characterize the seismicity of a region basically involves a good knowledge of its geology, tectonics and seismic phenomenology. The investigation becomes reliable and the attribution of the intensity degree correct at a site when there is careful observation followed by critical analysis of the effects of the earthquake on people and their environment, the buildings and ground. The scale of intensity, which ever one it may be — but here we shall refer to the MCS and MSK scales mentioned above — shows intervals (degrees of intensity) that are nor fully definable in extent nor comparable one with another on account of the heterogenous nature of the classification factors (indices) These limits are not, so much inherent in the intensity as an index of the strength of the earthquake as in the real difficulties of « measuring » it. Percentages of the building works damaged broken down, according to the type of work, into groups A, B and C together with the classification of damage ( f r o m 1st to 5th degree)

St 2nd 3rd 4 th 5 th

Findings

CONCLUDING REMARKS