Back-analysis of an important sand liquefaction event triggered by the 1870 Charlevoix earthquake, Quebec, Canada

ABSTRACT: Unlike high-seismicity regions such as California, Japan or New Zealand, only a few cases of soil liquefaction have been reported historically in the northeastern United States and eastern Canada, where moderate-to-large earthquakes capable of triggering liquefaction are much less frequent. This paper is aimed at documenting one of these liquefaction events, which was triggered in 1870 in the Charlevoix region, Quebec, by an earthquake with a moment magnitude estimated to be in the range 5.8-6.5. Uncertainties in dynamic site response analyses are accounted for by considering four seismic scenarios and several soil resistance profiles obtained from field penetration testing inside and outside the liquefaction zone. For each scenario, synthetic ground motions generated with a stochastic finite-fault model were used to simulate sites response. Results suggest that the most likely scenario for liquefaction triggering was an earthquake with a magnitude of 6.5 at a distance less than or equal to about 10 km.