Liquefaction Analysis of Sandy Soil Induced by the Mw 6.1 Sullana Earthquake of 2021 in the Urban Center of Isla San Lorenzo, Northern Peru

Araujo W. · Civil Engineering and Architecture (2025) · DOI: 10.13189/cea.2025.131342

Resumen

Significant soil liquefaction effects were observed in the urban area of La Isla San Lorenzo following the Mw 6.1 earthquake that occurred on July 30, 2021, in northern Peru. The epicenter was located 12 km west of the city of Sullana, in the Piura region, an area characterized by alluvial deposits and a shallow water table, which contribute to high liquefaction potential. These effects were manifested through the formation of sand boils, ground fissures, and water ejection, leading to visible ground instability and potential damage to infrastructure. To assess the liquefaction potential in the affected area, a geotechnical analysis was performed using both empirical and numerical methods. The classical liquefaction potential method by Seed and Idriss (1971) was applied to evaluate the factor of safety against liquefaction, indicating the presence of liquefiable soil layers down to a depth of 8m. Additionally, a one-dimensional (1D) numerical analysis was conducted using the PDMY02 constitutive model by Elgamal (2002), which simulates the cyclic behavior of sandy soils under seismic loading. This model, based on a pore pressure ratio threshold, identified liquefaction triggering up to a depth of 6 m. Furthermore, shear strain analysis confirmed the occurrence of significant deformations associated with liquefaction. The combined results of empirical and numerical approaches highlight the vulnerability of La Isla San Lorenzo to liquefaction hazards, emphasizing the need for improved site-specific seismic hazard assessments and mitigation measures in future urban planning and infrastructure development.

Instituciones: Universidad de Piura