Historical seismic catalogue updates and site effects considerations for southern Piedmont (Northwest Italy)

Abstract

In Northwest Italy, the definition of the seismic districts is a debated topic, with relatively scarce literature to pursue the goal of assessing the relative seismic potential. In particular, the southern Piedmont, despite being part of the lowest categories in the Italian seismic zonation map, has been affected by four relevant earthquakes between 5.5 and 6.5 M w in the last six centuries. Starting from the Italian Historical Macroseismic Archive catalogue, a consultation of ten historical archives (in parishes, municipalities, and administrations of Alessandria, Asti, Cuneo, and Turin Provinces) improved the historical seismicity information reported in the Italian Macroseismic Database, verifying the presence of unknown Macroseismic Data Point (MDPs). An analysis of the density of instrumental seismicity epicentres of the last 35 years provides consistency with MDPs density, qualitatively finding spatial correlation between them. In addition, a deepening of earthquake-induced landslide issue has been performed in a georeferenced environment with the purpose to assess eventual local amplification effects through a geostatistical analysis.