Fragility and vulnerability curves of masonry buildings on slow-moving landslides: A comparative study on intensity parameters from MT-InSAR

Abstract

Slow-moving landslides pose prolonged and severe damage to buildings. Quantifying the vulnerability of buildings is a critical step of landslide risk assessment, with landslide intensity serving as a key parameter in quantifying the vulnerability of exposure elements. However, current fragility or vulnerability modeling lacks the comparison of different intensity parameters and provides limited guidance in determining the most appropriate intensity parameter. To this aim, this paper carries out the generation and comparative study of fragility and vulnerability curves considering different intensity parameters by MT-InSAR technology. We collected 32 ENVISAT and 193 Sentinel-1A images to derive landslide intensity including maximum sliding velocity, cumulative displacement, maximum vertical velocity and differential vertical displacement through MT-InSAR technology. About 50 damaged masonry buildings were found out among near 500 residential buildings on landslides in field survey. These buildings are classified considering damages on walls and ancillary structures. Based on this, we then developed fragility and vulnerability curves using Polynomial, Exponential, Logistic, Weibull, and Sigmoid nonlinear regression functions. The results indicate that building damage responds more acutely to surface deformation in the vertical direction. In terms of fitting functions, the Sigmoid function performs optimally with cumulative displacement or maximum sliding velocity as intensity parameter, whereas the Weibull function yields the best fit with differential vertical displacement or maximum vertical velocity as intensity parameter. Vulnerability curve generated with the maximum sliding velocity or maximum vertical velocity as intensity parameter is generally applicable, while curves derived from cumulative displacement or differential vertical displacement are more suitable for the slow-moving landslides with low temporal heterogeneity in movement. In the context of slow-moving landslide risk assessment in the TGRA, we suggest to use maximum vertical velocity to analyze vulnerability of masonry buildings on slow-moving landslides.