Abstract
In this study, a method for simulating the ground motion of megathrust earthquakes at periods of approximately 2 s and longer was validated by using the characterized source model combined with multi-scale spatial heterogeneity. Source models for the M W 8.3, 2003 Tokachi-oki earthquake were constructed, and ground motion simulations were conducted to test their performance. First, a characterized source model was generated based on a source model obtained from waveform inversion analysis. Then, multi-scale heterogeneity was added to the spatial distribution of several source parameters to yield a heterogeneous source model. An investigation of the Fourier spectra and 5 % damped velocity response spectra of the simulated and observed ground motions demonstrated that adding multi-scale heterogeneity to the spatial distributions of the slip, rupture velocity, and rake angle of the characterized source model is an effective method for constructing a source model that explains the ground motion at periods of 2–20 s. It was also revealed how the complexity of the parameters affects the resulting ground motion. The complexity of the rupture velocity had the largest influence among the three parameters.
Highlights
Megathrust (MW > 8) earthquakes have occurred and will potentially occur in the vicinity of the islands of Japan, including along the Kurile Trench, the Japan Trench, the Sagami Trough, the Nankai Trough, and the Ryukyu Trench
An investigation of the Fourier spectra and 5 % damped velocity response spectra of the simulated and observed ground motions demonstrated that adding multiscale heterogeneity to the spatial distributions of the slip, rupture velocity, and rake angle of the characterized source model is an effective method for constructing a source model that explains the ground motion at periods of 2–20 s
Long-period components of ground motion are computed using a deterministic approach with a theoretical representation of the rupture and wave propagation processes; it is important to construct an appropriate source model and a three-dimensional (3D) velocity structure model. 3D long-period ground motion simulations for future megathrust earthquakes have been presented by numerous works (e.g., Olsen et al 2008; Pulido et al 2015)
Summary
Megathrust (MW > 8) earthquakes have occurred and will potentially occur in the vicinity of the islands of Japan, including along the Kurile Trench, the Japan Trench, the Sagami Trough, the Nankai Trough, and the Ryukyu Trench. Long-period components of ground motion are computed using a deterministic approach with a theoretical representation of the rupture and wave propagation processes; it is important to construct an appropriate source model and a three-dimensional (3D) velocity structure model. Iwaki et al Earth, Planets and Space (2016) 68:95 seismic hazard evaluation considering the uncertainties of the source parameters (Maeda et al 2013; Iwaki et al 2013). These simulations used the 3D Japan integrated velocity structure model (JIVSM; Koketsu et al 2009) and kinematic source models based on the concept of characterized source models (Irikura and Miyake 2001, 2011).
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