A preliminary study of seismic microzonation of Concepción based on microtremors, geology and damages patterns

we perform microtremors measurements at concepción and compute the predominantfrequency using horizontal-to-vertical spectral ratio (hvsr). we compare these results with the surface geology and several geotechnical surveys existing in the region, enabling a general characterization of the area. we present and complement these results with observations of damage produced by the mw 8.8 maule 2010 earthquake. preliminary results show the presence of fine-grained materials in the area characterized by very low predominant frequency (lower than 1.5 hz), which might explain the extensive damage observed at concepción and surroundings.