Effects of topography and basins on seismic wave amplification: the Northern Chile coastal cliff and intramountainous basins

SUMMARY During earthquakes, structural damage is often related to soil conditions. Following the 2014 April 1 Mw 8.1 Iquique earthquake in Northern Chile, infrastructure was reported cities of and Alto Hospicio. In this study, we investigate causes site amplification region by numerically analysing effects topography basins on observed waveforms frequency range 0.1–3.5 Hz using spectral element method. We show that produces changes amplitude seismic waves (amplification factors up 2.2 Hz) recorded stations located steep areas such as ca. 1-km-high coastal scarp, a remarkable geomorphological feature runs north–south, parallel coast trench. The modelling also shows secondary waves—probably reflections from scarp—propagate inland offshore, augmenting duration ground motion energy factor three. Additionally, find that, expected, have considerable effect at within surrounding areas. This can be attributed generation multiple reflected basins, which increase both motion, with an 3.9 for frequencies between 1.0 2.0 Hz. Comparisons real synthetic accounting good agreement 0.1 0.5 However, higher frequencies, fit progressively deteriorates, especially or near topography, basin areas, sites superficial soft sediments. poor data misfit high most likely due shallow, small-scale 3-D velocity heterogeneity, not yet resolved images our study region.