Basin and Sub-Basin Response to Long-Period Ground Motion: Implication from the 3D Finite-Difference Simulation

Abstract eng:
The 2003 Tokachi-oki earthquake (Mw 8.3) generated significant long-period ground motion and extended duration of a few hundred seconds in the Yufutsu basin, where oil tanks at Tomakomai were damaged by sloshing due to the long-period ground motion. General characteristics of long-period ground motion due to the combination of a large earthquake and a deep sedimentary basin were reproduced by large-scale finite-difference (FD) simulation in a period range of 3.3 to 25 s. In order to obtain a quantitative understanding of the long-period ground motion, we herein focus on the basin and sub-basin response on long-period ground motion in the Yufutsu basin. Visualization of the 3D FD simulations indicates that the surface waves from the source direction are amplified in both the eastern and western parts of the basin at the first 100 s. During the next 100 s, the surface waves are still trapped inside the sub-basin composed of shallow layers, and these layers amplified ground motions and extended the duration in the western part of the basin. A series of computations with/without each velocity layer in the basin revealed the basin response to be amplified 1.5 to 2 times, and the sub-basin response as an extension of ground motion durations and amplification was revealed to be approximately 1.5 times. Our 3D FD simulations quantitatively clarified that the combination of both the basin and sub-basin response is essential for understanding of disastrous long-period ground motions in the Yufutsu basin during the 2003 Tokachi-oki earthquake.

• Export as: BibTeX | MARC | MARCXML | DC | EndNote | NLM | RefWorks
• Add to your basket