Abstract

On April 1, 2014, a strong Mw = 8.2 earthquake occurred on the coast of Iquique (Chile), with hypo central depth of 38.9 km. The reported intensity was VII (MM) in the cities of Arica and Iquique. As response to this severe event, an interdisciplinary team led by specialists from Universidad Austral de Chile (UACh) and Universidad Católica de Chile (UC), conducted a field exploration on the most affected areas. The purpose of this field trip was assessing observed seismic damage and correlate with possible site-effects on masonry buildings (3-5 stories). With this goal, six damaged buildings were analyzed, and 2 buildings without damage were considered too. With the purpose of evaluate the dynamic response of each building, the main vibration frequencies and modal shapes were obtained using triaxial accelerometers. On the other hand, to identify potential problems in soil-structure interaction, the predominant periods of soils applying the H/V spectral ratio method was also evaluated. Results of the field exploration and post-processing data shows evidence of poor performance in certain buildings that respond to problems of structural configuration and construction defects, mainly associated with the effects of short column. Moreover, the inclusion and evaluation of the dynamic soil and structural parameters, show that some structures were also affected by the soil-structure interaction, aspect that can explain some damage in apparent regular and well designed buildings.