Magnitude scaling relationships for liquefaction triggering procedures considering large magnitude subduction zone earthquakes

ABSTRACT: Along the coast of North America, including British Columbia, the Cascadia Subduction Zone is likely to produce a large-magnitude earthquake ranging from Mw =8-9.1, which is expected to trigger soil liquefaction, resulting in the loss of stiffness and strength and lead to ground failures of settlement or lateral movement. Within the liquefaction triggering procedures, the Magnitude Scaling Factor (MSF) is the relationship that accounts for the additional number of loading cycles for larger magnitude earthquakes. Current MSF relationships were developed for earthquake magnitudes consistent with crustal faulting (Mw<8.0). Hence, it is not fully understood if these relationships can confidently predict intra- and inter-plate earthquakes produced by Cascadia. In this study, a suite of ground motions from the NGA-subduction zone database is used to assess if the current magnitude versus the number of cycle relationships (Mw-Ncyc) correctly predicts the significant number of loading cycles for intra- and inter-plate earthquakes. The current Mw-Ncyc relationships overpredicted the number of cycles for subduction zone inter-plate events at midrange magnitudes, while intra-plate events produce more significant loading cycles than crustal or inter-plate subduction zone relationships predicted at the same magnitude. The revised Mw-Ncyc relationships are recommended to be used in design practice when dealing with subduction zone tectonic environments both locally and abroad.