Simulation of ground motion using stochastic point-source method for earthquakes located in different source zones in Taiwan
Speaker: Saifuddin
Abstract
Point source stochastic method is a simple and powerful for simulating high frequency ground motions by combining parametric or functional descriptions of the ground motion’s amplitude spectrum with a random phase spectrum modified such that the motion is distributed over a duration related to the earthquake magnitude and to the distance from the source. ?The method was performed at rock (class B) sites from 2800 acceleration records from M > 3.0 – 3.5 earthquakes occurred in 1993-2004 located in the northern and eastern parts of Taiwan. Parameters of geometrical spreading and an-elastic attenuation were verified using acceleration spectra corrected for the site effect. The horizontal-to-vertical Fourier spectral ratio of the S-wave phase was used for the correction. Analysis on effect of earthquake locations were divided into three characteristic zones, namely: shallow (hypocentral depth < 30-35 km) earthquakes occurred beneath central Taiwan, shallow offshore earthquakes occurred to the east of island, and deep earthquakes (depth> 35 km).? Source spectra in Taiwan region may be described by the ω-square spectral model (Brune, 1970) after analyzing on spectra corrected for site effect, attenuation, and the influence of upper crust (kappa-factor). The value of seismic moment is estimated from regional relationships between seismic moment and local magnitude. The stress parameter should be considered as a magnitude-dependent quantity (120-150 bars for M 5.0 and 250-300 bars for M 6.8) for shallow earthquakes beneath central Taiwan while the offshore and deep earthquakes are characterized by relatively constant values of the stress parameter.
Reference
Boore, M. David,2003, Simulation of Ground Motion Using the Stochastic Method, Pure appl. geophys. 160, 635–676
Sokolov, Vladimir, Chin-Hsiung Loh, and Wen-Yu Jean, 2006.Strong Ground Motion Source Scaling and Attenuation Models for Earthquakes Located in Different Source Zones in Taiwan, ?4th International Conference on Earthquake Engineering, Taipei, Taiwan October 12-13