A generalised severity number to predict liquefaction damage with lateral spreading

This study introduces a generalisation of the classical one-dimensional liquefaction severity indexes to extend their predictive capability for the occurrence of lateral spreading. After a critical overview of the most used indexes, the rationale for extension to bi-dimensional conditions determined by non-horizontal geomorphology is presented, together with the rule to achieve generalisation. The efficacy of the new index is demonstrated with a performance-based study on two cases, the earthquakes of 20 May 2012 (M-w 6 center dot 1) at Terre del Reno (Emilia-Romagna, Italy) and 11 February 2011 (M-w = 6 center dot 2) at Christchurch (New Zealand). Stratigraphic attributes including thickness, depth, composition and relative density of the liquefiable layers, obtained over the whole territories from rich datasets of cone penetration tests, are coupled with topographic information derived from the digital elevation model to provide the input for the analysis. Consistency assessment and spatial interpolation of data are carried out with geostatistical tools implemented in a geographic information system platform. Validation against a post-earthquake damage survey, quantified with a binary classification method, shows the paramount role of the bi-dimensional conditions.

Automated summary

This study extends the classical one-dimensional liquefaction severity indexes to improve predictive capability for lateral spreading, demonstrating efficacy through two earthquake case studies. The new index combines stratigraphic attributes and topographic information for analysis, with validation against post-earthquake damage surveys highlighting the importance of bi-dimensional conditions.