Seismically induced soil liquefaction and geological conditions in the city of Jama due to the M7.8 Pedernales earthquake in 2016, NW Ecuador

Abstract

Seismically induced soil liquefaction was documented after the M 7.8, 2016 Pedernales earthquake. In the city of Jama, the acceleration recorded by soil amplification reached 1.05 g with an intensity of VIII to IXESI07. The current study, integrates geological, geophysical and geotechnical data to build up a geological characterization of the subsoil for the city of Jama in Manabi province in Ecuador. Then the liquefaction potential index (LPI) has been evaluated considering the PGA-rock values calculated from deterministic methods applied to nearby geological faults, as well as the soil acceleration records for the city of Jama since the Pedernales megathrust earthquake. The importance of conducting geotechnical evaluations of a particular colluvial, alluvial and floodplain deposits, for which the liquefaction probability profiles were also obtained, may serve as an useful tool for buildings foundations or earthquake resistant designs. Finally, the site response analysis is presented using a linear equivalent analysis, where previously seismic records compatible with the target spectrum have been selected. Hereby, the results of ground surface effects have been compared with the spectra of the Ecuadorian Regulation of Construction (NEC) in the context of local seismic amplification.