Automated assessment of macroseismic intensity from written sources using the Fuzzy sets

Abstract

We apply a computer-aided methodology to assess macroseismic intensity from the descriptions reported by documentary material available for eight Italian earth- quakes occurred around the beginning of the instrumental era. The procedure consists of three phases: (i) the identification of significant macroseismic effects on the sources and their archiving in a georeferenced database, (ii) the association between the effects and the degrees of the intensity scale by the comparison with traditional estimates made by macroseismic experts, (iii) the assessment of intensities using a multi-attribute decision- making algorithm based on the Fuzzy Sets logic. This work represents a substantial im- provement of our previous efforts as we completely redesigned the three phases of the procedure in the light of the experience of the last 10 years and analyzed six further Italian earthquakes so that our database now includes more than 19,000 encoded effects. Our formalized procedure allows to tracing all of the steps of intensity assessment process so that to identify discrepancies with respect to the expert evaluations that might be possibly due to mistakes or to the incomplete account of the available information. Hence, this approach may be useful for providing a systematic and reproducible intensity assessment as well as for supporting standard man-made assessments. The database of effects we have built could also be employed for testing the internal consistency of the macroseismic scale as well as for designing an improved macroseismic scale, based on consistent statistical criteria.