AUTHOR=Núñez-Jara S. , Montalva G. , Pilz M. , Miller M. , Saldaña H. , Olivar-Castaño A. , Araya R. 

TITLE=Spatial variability of shear wave velocity: implications for the liquefaction response of a case study from the 2010 Maule Mw 8.8 Earthquake, Chile

JOURNAL=Frontiers in Earth Science

VOLUME=Volume 12 - 2024

YEAR=2024

URL=https://www.frontiersin.org/journals/earth-science/articles/10.3389/feart.2024.1354058

DOI=10.3389/feart.2024.1354058

ISSN=2296-6463

ABSTRACT=Assessing the potential, severity, and extent of earthquake-induced liquefaction is paramount for seismic hazard assessment, for the large ground deformations it causes can result in severe damage to infrastructure and pose a threat to human lives, as evidenced by many contemporary and historical case studies in various tectonic settings. In that regard, numerical modeling of case studies, using state-of-the-art soil constitutive models and numerical frameworks, has proven to be a tailored methodology for liquefaction assessment. Indeed, these simulations allow for the dynamic response of liquefiable soils in terms of effective stresses, large strains, and ground displacements to be captured in a consistent manner with experimental and in-situ observations. Additionally, the impact of ground motion and spatial variability in liquefaction can be assessed, because the element and system response to waves propagating are naturally incorporated within the model. Considering that, the effect of shear wave velocity V_s variability, a fundamental soil property,  has not been thoroughly assessed. In a case study in Metropolitan Concepcion, Chile, our research addresses the influence of V_s spatial variability on the dynamic response to liquefaction. At the study site, the 2010 Maule M_w 8.8 Earthquake triggered liquefaction-induced damage in the form of ground cracking, soil ejecta, and building settlements. 
Using simulated 2D V_s profiles generated from real 1D profiles retrieved with ambient noise methods, along with a PressureDependentMultiYield03 calibrated constitutive model, we studied the effect of V_s spatial variability on pore pressure generation, vertical settlements, and shear and volumetric strains. Our findings indicate that increased V_s variability reduces the median settlements and strains for soil units that exhibit liquefaction-like responses. On the other hand, no significant changes in the dynamic response are observed in soil units that exhibit non-liquefaction behavior, implying that the triggering of liquefaction is not influenced by spatial variability in V_s. We infer that when liquefaction-like behavior is triggered, an increase of the damping at the element level in the shallowest part of the soil domain might be the explanation for the decrease in the amplitude of the strains and settlements as the degree of V_s variability increases.