Several probabilistic liquefaction triggering approaches, or liquefaction manifestation severity approaches, have been developed to consider the uncertainties related to liquefaction and its manifestations. Probabilistic approaches are essential for vulnerability and risk models that considers the consequences of liquefaction on building performance. They may be incorporated into a performance-based earthquake engineering framework through a fully probabilistic liquefaction hazard assessment. The objective is to effectively incorporate spatial interaction of two concurrent hazards, specifically earthquake-induced shaking, and liquefaction, and to develop a robust multi-hazard framework applicable to regions with limited input data. For this purpose, it is necessary to establish, according to the available probabilistic liquefaction triggering or manifestation severity assessment approaches, which set of approaches aligns optimally with vulnerability and risk models. Thus, this paper discusses the current methodologies on the ongoing probabilistic liquefaction hazard assessment approaches with the aim of defining a reliable model specific for areas with a non-liquefiable surface layer over a liquefiable layer.

The east of Cali is composed of loose sand deposits with high water table levels. This condition and the high seismic hazard of the city make cyclic liquefaction one of the main hazards in the city, which may affect more than 600,000 citizens and important infrastructures such as the city’s main drinking water treatment plants. Therefore, it was decided to design and implement a seismic monitoring center to study the behavior of liquefiable soils under local seismogenic conditions, in which subduction earthquakes predominate. First, more than 130 earthquakes from two seismic monitoring centers with liquefiable layers in the USA were studied to determine the requirements for the adequate design of the monitoring center. Then, a robust geotechnical and seismic characterization of the study area including SPT, CPTu, and seismic and ambient noise tests were carried out. From this information, the specifications and location of the instruments and, in general, the characteristics of the monitoring center were defined. The monitoring center has been planned to be established in two stages, and the first one has already been built and commissioned. The implementation of the first stage allowed to adequately record 35 earthquakes from different seismogenic sources, most of them from subduction earthquakes, and to verify that the potentially liquefiable layer remains saturated throughout the year. Subsequent ground motion sensors will allow to deeply study and understand large shear strains and excess pore pressures generation in the soil deposit, as well as their relationships with different intensity measures. The experience shared herein can benefit the design, construction, and operation of other seismic monitoring centers across the world.

On 28 March 2025, a devastating M 7.7 earthquake struck Myanmar along the right-lateral strike-slip Sagaing fault, followed by an M 6.7 aftershock twelve minutes later. This study presents a comprehensive assessment of the earthquake’s effects through recorded strong ground motions, macroseismic intensity observations, secondary hazards including liquefaction, and remote sensing-based damage detection. The supershear rupture spanned ∼460 km, with pronounced fault directivity effects resulting in high peak ground acceleration values of up to 0.57g recorded for the horizontal components and macroseismic intensities reaching modified Mercalli intensity = X in nearby cities. Analysis of acceleration time series and Fourier amplitude spectra at nearby recording stations revealed significant near-field effects and spectral exceedances over Myanmar National building code design levels, particularly in the short-period range, affecting mostly low-rise structures. Secondary hazard evaluation indicates widespread liquefaction, especially near the Irrawaddy River, supported by correlations between cumulative absolute velocity and liquefaction probability maps. Remote sensing analysis using multitemporal Advanced Land Observation Satellite-2 Synthetic Aperture Radar (SAR) coherence data identified severe building and road damage in urban centers. A differential coherence method, coupled with urban masking and OpenStreetMap road data, enabled spatial quantification of damage, revealing over 39,000 km of roads and 306 km2 of buildings with moderate-to-heavy damage. The results provide critical insight into the earthquake’s impact and demonstrate the joint evaluation of ground-motion analysis and SAR-based damage mapping for rapid seismic response.

Cyclic liquefaction is a phenomenon in which soil deposits formed by loose and saturated sands, lose their shear resistance due to dynamic loads, as earthquakes, sometimes causing the collapse of structures. This phenomenon is a hazard in different cities of the world, as is the case of Santiago de Cali (Colombia), a city that has large alluvial deposits due to its seven rivers. Currently, the liquefaction potential is evaluated by field tests that can be expensive and difficult to perform in densely urbanized areas. Due to this drawbacks, this paper proposes a simple and versatile methodology to evaluate the liquefaction potential in large areas based on the vulnerability index ($K_g$ ) proposed by Nakamura in 1997 (hereinafter Nakamura Methodology). This methodology consists of calculating the vulnerability index using the fundamental frequency ($F_g$ ) and amplification factor ($A_g$ ) determined using HVSR method. The $K_g$ index quantifies the probable damage in the soil produced by earthquakes, and for sand deposits, $K_g$ can be correlated with liquefaction potential. For this research, the liquefaction potential was evaluated using Nakamura methodology in 34 points of Santiago de Cali, within an approximate area of 12 km². The results were compared with those of SPT and CPT tests performed in the same area. The methodology showed a match of up to 82% compared to conventional methods. In conclusion, Nakamura methodology is a viable alternative for liquefaction hazard mapping of large areas and could be very useful in places where there are limited funds or the conditions for more robust testing are not available.