Abstract
Strong earthquake motion record obtained from a seismometer array record at Kobe Port Island during the Hogoken Nambu earthquake of January 1995 is employed to inversely analyze the dynamic soil parameters, i. e. dynamic shear modulus and damping ratio of each layer. The extended Baysian method (EBM) is employed to overcome the problem of illposedness. Some trade off between the shear modulus and the damping ratio is observed. Also the solution is not unique. Such kind of trade off have been successfuly solved by EBM for relatively smaller earthquake motion records in the previous studies (Honjo et. al, 1997, 1998). It is speculated that this problem arose because of the extraordinarily strong earthquake motion record obtained, and approximating this phenomena by the equivalent linear model. Discussion is made both from statistical and soil dynamic view points on the problem.
