Evaluation of 1947-1993 macroseismic information in Portugal using the EMS-92 scale

Abstract

In the present work macroseismic information of the earthquakes felt in Continental Portugal from 1947 to 1993 was evaluated using the EMS-92 intensity scale. Press information, and data in the seismological questionnaires used in this period of time, were used as prime information. Prior intensity assignments were also used in the analysis. Two methodologies -A and B -were followed, according to the type of information available: A) whenever seismological questionnaires or descriptions of effects are accessed this information was analysed leading to an intensity value and to an intensity quality factor; this methodology includes a standardisation of questionnaire evaluation, through the use of conversion keys; B) if only an intensity assignment, in any known scale, existed, then a conversion of intensities was made. The results of these two methodologies are compared and discussed. Based on the above mentioned information a database with 1947-1993 Portuguese seismic information was built up, and a few features of its contents were discussed.