NUMERICAL SIMULATIONS OF EARTHQUAKE SOURCE PROCESS BY A THREE-DIMENSIONAL CRACK MODEL.

PART II. SEISMIC WAVES AND SPECTRUM

抄録

We study the seismic waves and spectrum generated by a dynamical rupture process by a three-dimensional crack model obtained in Part I (MIYATAKE, 1980). The fracture condition used here is a finite stress fracture criterion, while the strength is assumed to be distributed irregularly. It is found that complex seismic waves are generated by the irregular rupture process rather than by the complex source-time functions. Near-field and far-field seismic wave radiated from the fault with the above distribution are also calculated. Seismic waves from the fault with a line barrier and a block barrier have almost similar wave shapes. Random barrier distribution radiates high frequency seismic waves, and the spectral amplitudes tend to decay inversely in proportion to the frequency in the range beyond the corner frequency.