The MERISUR Project (Methodology for an Effective RISk assessment of URban areas) aims at developing an effective methodology for urban seismic risk assessment that provides solutions to some deficiencies detected after recent damaging events worldwide, including risk mitigation actions based on benefit/cost ratios.

First, the hazard and vulnerability models used for risk estimation are developed and improved. A procedure to determine the seismogenic fault that controls seismic hazard for a given probability level is established. Methods to include active faults as individual seismogenic faults and to consider near filed effects (directivity, hanging wall effect) that significantly amplify ground motions (as observed in the 2009 L’Aquila, 2010 Christchurch or 2011 Lorca events) will be proposed.

A more complete description of seismic vulnerability is accomplished, encompassing structural, non-structural components. Vulnerability modifiers to incorporate effects or urban parameters on vulnerability classes are also quantified.

A distinction is also made between damage to structural and non-structural building elements. For this purpose, a pushover analysis is specifically carried out to model building response and damage trends on non-structural elements. This gives the primary damage. In addition, the resulting debris volume and the area covered by this debris is also estimated both in inner space (within the building) and in the outer space (public roads and areas). I this way, a volume of debris will be associated to each area unit of the city, and will cause damage to persons and elements exposed therein, such as urban furniture and vehicles. This constitutes the secondary damage.

A static level of occupation (building, urban furniture, etc.) and a dynamic level of occupation (persons, vehicles) will be assigned to each area unit of the city, hereby defining the exposure in time and space.

To estimate earthquake losses, a table of costs (demolition, reparation, reconstruction, and replacement) related to primary damage of building components (structural and non-structural) will be elaborated. At the same time, losses related to secondary damage will be also assessed. This will require developing new tables classifying the vulnerability of exposed elements such as urban furniture and vehicles and quantifying losses per damage degree. In all cases, the amount of fatalities and injured people will be assessed. A dual classification of earthquake impact including both economic and human losses will be proposed.

Cost/benefit ratios between ex ante risk mitigation measurements will be developed in order to decide whether risk transfer of risk retention is preferable for different risk scenarios. This analysis will confer effectiveness to the results of a seismic risk study. Overall, the estimate of earthquake losses and cost/benefit ratios are topics with little presence in the scientific literature concerning damaging earthquakes in Spain. Thus, the results of this study will provide effective solutions to the challenge to society tackled in this proposal. In this line, the project is completed with a set of geomatic tools, such as a geographic information system and a web map server, for disseminating all the information and results of the project. This server will be accessible via web and will include query tools to help the final users in interpreting the results.