Historical damage pattern and causes of differential damage: an approach based on combining geophysical prospecting, geological and historical-technical data

We describe a multidisciplinary and interdisciplinary method to analyse the causes of differential macroseismic effects caused by an earthquake in a historical town. We illustrate the method with a case study based on analysing the damage caused by the 1930 Irpinia earthquake (Me=6.7) in Melfi, a town in southern Italy. A damage pattern map was already available for this site. To understand the anomalies of Melfi damage, we used an integrated approach that combines geological surveys, geophysical prospecting and analysis of unpublished technicalhistorical data. Geo-electrical prospecting was adopted to infer the geological set-up and to estimate the thickness of shallow deposits. The results of the geophysical surveys were compared with detailed geological information derived from both in situ surveys and boreholes. Finally, cross-correlation among these data and technical reports coeval to the earthquake allowed us to create a complete picture of the possible causes of uneven damage.