Two earthquakes of magnitudes 6.7 and 7.4 that occurred in 1978 off the Pacific coast of Miyagi Prefecture, Japan, provided field liquefaction data for a fairly wide range of peak ground surface acceleration from 100 to 290 gal. The range of SPT N-values was also fairly wide because special efforts were made to collect non-liquefaction data in addition to liquefaction data. Dynamic shear stress ratios adjusted for earthquake magnitudes and effective overburden pressures are plotted against N-values adjusted for effective overburden pressures. The field data are compared with two methods proposed recently, one by Seed and the other by Iwasaki et al, after a critical review of the methods and the SPT\u27s in the U.S. and Japan. The method by Seed tended to underestimate the resistance to liquefaction for small N-values, particularly for silty sands; whereas the method by Iwasaki et al tended to underestimate the resistance to liquefaction for large N-values
