Regional vulnerability and risk assessment accounting for local building typologies

Seismic risk analysis allows investigating the consequences of earthquakes in a region of interest. Most of the existing risk-oriented studies focus on new developments and/or on the integration of most up-to-date information in the fields of seismic hazard evaluation and vulnerability assessment. Conversely, no specific effort was devolved on evaluating the influence of exposure modeling; most of the studies rely on census data at the municipal level for the development of building inventory. Building inventory may change if more information on vulnerability factors for building typologies is considered and this may lead to a different estimation of losses with respect to those based on traditional inventories relying on census data alone. The recent Cartis approach, based on interview, represents an advancement for compilation of regional scale inventories; it allows to rapidly acquire much more data on building typologies with respect to census returns. This paper explores the issue of exposure modeling by comparing the seismic risk computed at the regional scale starting from variable knowledge levels of the building environment. It will be shown that the seismic risk computed starting from the enhanced exposure modeling is generally higher with respect to the standard census-based one. The seismic risk can be nearly doubled for some towns, and the variation is more significant for smaller towns (with smaller number of inhabitants). This result may have a significant influence on evaluations that are based on comparative risk analysis at the regional scale, conditioning decisions towards risk mitigations campaigns or calibration of insurance premiums.