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Strong Motion Pulse Generation Areas for Huge Subduction Earthquakes - Their Scaling with Overall Earthquake Size -

Publication year Port and Airport Research Institute Technical Note 1257 2012.09
Author(s) Atsushi NOZU,Takashi NAGAO
Department
/Divison
Earthquake Disaster Prevention Engineering Field Engineering Seismology Group
Executive Summary

Prediction of strong ground motions in the frequency range from 0.2 to 1 Hz is quite important for a wide range of engineering structures including port structures. Strong ground motions in this frequency range 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 such as the 1995 Hyogo-ken Nanbu earthquake and the 1994 Northridge earthquake, in a sense that they appear in a frequency range of engineering importance. Thus, not only strong motion pulses from shallow crustal earthquakes but also those from huge subduction earthquakes can cause significant damage to structures. Therefore, 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 overall size of the earthquakes.

PDF File /en/pdf/en/no1257.pdf