An effective stress model is a promising technique in meeting increasing demands for higher accuracy in assessing liquefaction potential in detail. In order to study its applicability, the effective stress model developed by one of the authors is compared with field performances during a large earthquake in the present report. It is essential for carrying out the comparison that full information be compiled on the liquefaction data, the ground conditions, and the input ground motions. Ishinomaki Port during the 1978 Miyagi-Ken-Oki Eartuquake provided a good opportunity for obtaining such information.
　In addition to such information, sand specimen were taken form Ishinomaki Port and tested in a laboratory using a simple shear apparatus. The effective stress model applied for sand specimen was studied in detail for concerning influence of vertical confining pressure on liquefaction strength.
　Most of the parameters of the effective stress model were thus estimated for the simulation. Simulation of ground performances by this model gave results similar to the observed ground performances at the liquefied and the non-liquefied areas.