The local scale: Barcelona, Spain
The local scale application of the computer prototype was carried out for the city of Barcelona, located in Catalonia, NE of the Iberian Peninsula, at the Mediterranean coast. The urban area of Barcelona has a population of 1,650,000 inhabitants, while its metropolitan area reaches up to 3,000,000 inhabitants. The economic and social development of Barcelona, which has produced dramatic changes in recent years, and its geographical location — Barcelona urban area is built on a pediment plain in-between two rivers — has notably increased seismic risk. For the first time an attempt has been made to combine in a single application the evaluation of hazard and risk scenarios for Barcelona urban area.
The integrated approach followed in order to obtain earthquake hazard scenarios in Barcelona was carried out in several steps (Jiménez et al., 1999a). Data relevant to local geology (age and lithology), subsurface layering and soil mechanical properties were compiled and implemented as coverages in the GIS and a simplified 3-D geotechnical model was generated based on this information. Next, the expected level of bedrock ground shaking through the definition of seismic hazard and attenuation at regional scale was established. Then, due to the lack of available strong motion data, the definition of a reference ground motion time history was obtained through the Empirical Green's Functions method (EGF’s) developed by Hutchings (1988), using the EMPSYN program. A EGF's-simulated M=6.0 synthetic accelerogram scaled to 0.04g, according to the value given at Barcelona by the Spanish Building Code, has been used as seismic input at bedrock level. Finally, the site response analysis was performed using the 1-D linear equivalent method of SHAKE91 (Idriss and Sun, 1992) which assumes a system of homogeneous, horizontally layered viscoelastic soil deposits. SHAKE91 has been integrated with procedures that enable it to start directly from data stored in the GIS.
Although preliminary earthquake risk scenarios have been generated for the 10 districts in which the city is divided, a detailed study has been performed in one of them, called Eixample, and located in the central part of the town, to test the complete local scale sequence implemented in the prototype. The horizontal peak acceleration obtained at ground level from the hazard scenario has been combined with the vulnerability index map of the district through available acceleration-vulnerability-damage empirical relationships, to obtain damage scenarios in the Eixample district.
Furthermore at local scale have been performed some remote sensing applications.
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SERGISAI - Contract Number: ENV4-CT96-0279 (DG 12 DTEE)
Project Coordinator: Gaetano Zonnozonno@irrs.mi.cnr.it