Abstract
Strong ground motions in the frequency range from 0.2 to 1 Hz observed at many sites along the coast of Miyagi through Ibaraki Prefecture during the 2011 off the Pacific coast of Tohoku earthquake are characterized by distinctive pulses. These strong motion pulses are similar to those from shallow crustal earthquakes in a sense that they appear in a frequency range of engineering importance. Because strong motion pulses from huge subduction earthquakes can also cause significant damage to structures, it is significantly important to consider the generation of such pulses in the strong motion prediction for huge subduction earthquakes, especially when the prediction is aimed at seismic design of structures. In this article, first, examples of strong motion pulses from huge subduction earthquakes are examined. Then, source models aiming at the reproduction of those pulses are compiled and the characteristics of SPGAs (Strong-motion Pulse Generation Areas) are investigated, with special attention to their relation to the size of the earthquakes.
