Analysis of liquefaction behavior during the 2011 off the Pacific coast of Tohoku earthquake

The 2011 off the Pacific coast of Tohoku earthquake (Mw9.0) caused many kinds of seismic hazard. In this paper, the liquefaction at Chiba bay area is investigated using the seismic records of K-NET. The K-NET seismic records of CHB008, CHB009 and CHB024 are analyzed by the non-stationary Fourier spectra and the response envelope spectra. The dominant frequency component is evaluated by the non-stationary Fourier spectra. The pulse wave which occurred after the main shock is composed of dual frequency components, which may result from the so-called cyclic mobility phenomenon. An artificial earthquake wave based on the seismic design code is compared with the measured seismic record using the velocity response envelope spectra. The necessity of revision of the seismic design code is discussed.