Dynamic Response of Short-Period Structures: Influence of Focal Depth in Peruvian Earthquakes

Abstract

Perú, located in the Pacific Ring of Fire, exhibits high seismic vulnerability, a critical issue given that a significant percentage of self-constructed housing lacks the necessary stiffness and ductility to withstand major events. To address this structural risk, this research validates a numerical methodology to evaluate the dynamic response of short-period structures ( Tn = 0.4 s) under Peruvian subduction earthquakes, specifically analyzing the influence of focal depth. Five real accelerograms (Arequipa 2001, Ica 2007, Tacna 2010, Tacna 2012, and the Lima 1974 aftershock) were processed using Butterworth filtering and baseline correction, calculating the response through Newmark's integration method. Results demonstrate that seismic demand is not linearly dependent on moment magnitude (Mw) but rather on source configuration and local site effects. It was observed that the Lima event (Mw 7.1), due to its shallow nature (12.8 km), generated the highest dynamic amplification factor (3.36). In contrast, the deep Tacna 2012 earthquake (98 km) recorded the lowest displacement (0.75 cm), evidencing energy attenuation in high-frequency waves. These findings validate the numerical methodology on a controlled physical model, establishing a fundamental baseline for future structural resilience assessments and specialized earthquake-resistant design in the region. Keywords—Focal Depth, Site Effects, Newmark Method, SDOF System, Peruvian Earthquakes