GEOPHYSICAL STUDY AND 2D NON-LINEAR MODELING OF SITE EFFECTS IN VIÑA DEL MAR CITY, CHILE

Abstract

The Maule earthquake of February 27, 2010 induced damage to several buildings throughout the central area of Chile. This was particularly the case in the downtown of Viña del Mar city, where an anomalous concentration of structural damage was found in several medium-rise buildings distributed along a narrow area of approximately 1 km in length. These observations suggest possible localized seismic amplification effects. A geophysical characterization using Surface-Wave based techniques and gravimetry were conducted to characterize the main dynamic properties of the soil and the depth of the basin. This data was complemented with several Standard Penetration Test (SPT) measurements to develop a geotechnical characterization of the area. Additionally, the cyclic behavior and mechanical properties of predominant materials were characterized experimentally based on remolded samples. Based on this whole description, a finite element model was developed to estimate possible singular site amplification effects explaining the concentration of structural damage in the area. The results suggest that the concentration of damaged buildings is probably most related to the basin depth (1D site amplification) than to the basin shape effects.