Comparative Evaluation of SAW and AHP Approaches for GIS-Based Liquefaction Susceptibility Mapping in Chiang Rai, Thailand

Liquefaction susceptibility mapping supports regional screening where detailed geotechnical data are limited. This study compared two GIS-based weighting approaches for Chiang Rai Province, Thailand: an equal-weight Simple Additive Weighting (SAW) model and an Analytic Hierarchy Process (AHP) model with differential weights. Both used the same four spatial factors-surface geology, slope, distance to rivers, and distance to active faults-with identical scoring criteria and spatial resolution. Internal discrimination was evaluated using 51 documented liquefaction occurrences from the 2014 Mw 6.1 Chiang Rai earthquake and 51 comparison points. SAW and AHP achieved AUC values of 0.923 (95% CI: 0.869–0.976) and 0.933 (95% CI: 0.883–0.983), respectively, with no significant difference (DeLong p = 0.244). The classified maps agreed over 69.86% of the study area, while high and very high susceptibility zones covered 27.56% for SAW and 33.87% for AHP. Pseudo-absence and spatial holdout analyses supported generally robust within-event discrimination. After removing distance to active faults, AHP significantly outperformed SAW (p = 0.022). Because all occurrence data came from one earthquake, results represent event-specific internal evaluation. Overall, SAW provides a transparent baseline, whereas AHP remains useful when differential factor importance is independently justified.