Compare methods

	Liquefaction Hazard Assessment	Liquefaction Triggering Analysis
Field	Disaster Studies	Disaster Studies
Family	Process / pipeline	Process / pipeline
Year of origin	2017	2001
Originator	Jing Zhu, Laurie Baise & Eric Thompson (geospatial model); engineering-geology liquefaction-zonation tradition	H. B. Seed & I. M. Idriss (original 1971 procedure); T. L. Youd & I. M. Idriss (NCEER consensus update)
Type	Spatial hazard-mapping pipeline combining susceptibility, demand and probability	Stress-based deterministic triggering pipeline
Seminal source	Zhu, J., Baise, L. G., & Thompson, E. M. (2017). An Updated Geospatial Liquefaction Model for Global Application. Bulletin of the Seismological Society of America, 107(3), 1365-1385.	Youd, T. L., & Idriss, I. M. (2001). Liquefaction Resistance of Soils: Summary Report from the 1996 NCEER and 1998 NCEER/NSF Workshops on Evaluation of Liquefaction Resistance of Soils. Journal of Geotechnical and Geoenvironmental Engineering, 127(4), 297-313.
Aliases	Liquefaction Hazard Mapping, Regional Liquefaction Susceptibility Mapping, Geospatial Liquefaction Modeling, Liquefaction Potential Zonation	Simplified Liquefaction Procedure, Seed-Idriss Simplified Procedure, CSR-CRR Liquefaction Analysis, Liquefaction Factor-of-Safety Analysis
Related	3	3
Summary	Liquefaction hazard assessment maps where earthquake-induced liquefaction is likely to occur and how severe its surface effects will be, across areas ranging from a city to a whole region. Unlike site-specific triggering analysis, which evaluates a single soil column from borehole data, regional assessment must predict liquefaction over wide areas where detailed subsurface data are sparse, so it relies on geospatial proxies for soil susceptibility together with a map of seismic demand. Zhu, Baise, and Thompson's 2017 geospatial model exemplifies the modern approach, predicting the probability of liquefaction from globally available variables such as slope-derived shear-wave velocity, a compound topographic index, and magnitude-adjusted peak ground acceleration, calibrated on documented liquefaction from past earthquakes. The Youd and Idriss 2001 consensus framework supplies the underlying site-scale physics and the severity indices that translate probability into expected damage. The product is a hazard map showing the spatial probability and intensity of liquefaction. It supports rapid post-earthquake response, loss estimation, and land-use planning where borehole-by-borehole analysis is infeasible.	Liquefaction triggering analysis evaluates whether saturated, loose granular soils will lose strength and behave like a fluid during earthquake shaking, using the simplified stress-based procedure that has anchored geotechnical earthquake engineering since Seed and Idriss introduced it in 1971. The method compares demand against capacity: the cyclic stress ratio (CSR) imposed by the earthquake versus the cyclic resistance ratio (CRR) the soil can sustain, both expressed as ratios of cyclic shear stress to effective overburden stress. Capacity is read from in-situ penetration tests — standard penetration test blow counts or cone penetration test tip resistance — through empirical curves calibrated on field case histories of sites that did and did not liquefy. The Youd and Idriss 2001 NCEER consensus report standardized these curves and the correction factors, and Idriss and Boulanger's 2008 monograph refined them. The ratio of resistance to demand gives a factor of safety against triggering at each depth. It is the workhorse first-order screen for liquefaction in routine practice worldwide.