1:45 PM - 3:15 PM
[SSS09-P17] Probabilistic Seismic Hazard Analysis of Response Spectra for Three Major Cities in Japan
Keywords:response spectra, probabilistic seismic hazard analysis (PSHA), seismic hazard curves, uniform hazard spectra
The Earthquake Research Committee (ERC) at the Headquarters for Earthquake Research Promotion in Japan creates and updates national seismic hazard maps, such as the “National Seismic Hazard Maps for Japan (2020),” to raise public awareness about disaster prevention and mitigation and help develop effective measures against earthquakes. These maps include probabilistic seismic hazard maps, which combine long-term probabilistic evaluations of earthquake occurrences with predictions of their strong motions, and specified seismic source fault maps that evaluate the strong motions of specific earthquake scenarios. The ERC creates and analyzes map-based response spectra for engineering purposes and seismic design. Recently, the ERC released a provisional probabilistic seismic hazard analysis (PSHA) of response spectra that includes main points, evaluation conditions, and results. By utilizing the ground motion prediction equation (GMPE) for response spectra, the provisional PSHA response spectra is intended to be materials for discussion on the evaluation conditions and results thereof of various natural periods.
The provisional edition focuses on 5% damped acceleration spectra on the engineering bedrock of Tokyo, Nagoya, and Osaka and calculates seismic hazard curves, uniform hazard spectra (UHS), and degrees of influence (i.e., contribution factors) by earthquake category. The UHS are based on periods of 0.1, 0.2, 0.3, 0.5, 1.0, 2.0, 3.0, and 5.0 s, with 2, 5, 10, and 39% probabilities of exceedance in 50 years. The provisional PSHA uses seismic activity models found in the “National Seismic Hazard Maps for Japan (2020)” and the GMPE proposed by Morikawa and Fujiwara (2013).
Figure 1 provides example results (i.e., Tokyo UHS and contribution factors by earthquake category) from the provisional document. The UHS entries illustrated in Fig. 1(a)–(c) help explain why subduction-zone earthquakes have the most significant impact. Figure 1(d) shows the contribution factors of two earthquake categories (5% probabilities of exceedance in 50 years) and confirms subduction-zone earthquake significance. Figure 1(e) presents the contributing factors of specific earthquake categories, revealing that interplate/intraplate earthquakes without specified source faults for the Philippine Sea plate have a significant influence in the short-period range, whereas those for the Pacific plate, Sagami Trough earthquakes, and Nankai Trough earthquakes have a significant influence in the long-period range.
We anticipate that the continued development of PSHA response spectra will contribute to the evaluation of structural responses for different exceedance probabilities and the implementation of seismic designs. The ERC is actively working toward effectively communicating PSHA response spectra results in ways that meet the needs and expectations of users for effective implementation.
The provisional edition focuses on 5% damped acceleration spectra on the engineering bedrock of Tokyo, Nagoya, and Osaka and calculates seismic hazard curves, uniform hazard spectra (UHS), and degrees of influence (i.e., contribution factors) by earthquake category. The UHS are based on periods of 0.1, 0.2, 0.3, 0.5, 1.0, 2.0, 3.0, and 5.0 s, with 2, 5, 10, and 39% probabilities of exceedance in 50 years. The provisional PSHA uses seismic activity models found in the “National Seismic Hazard Maps for Japan (2020)” and the GMPE proposed by Morikawa and Fujiwara (2013).
Figure 1 provides example results (i.e., Tokyo UHS and contribution factors by earthquake category) from the provisional document. The UHS entries illustrated in Fig. 1(a)–(c) help explain why subduction-zone earthquakes have the most significant impact. Figure 1(d) shows the contribution factors of two earthquake categories (5% probabilities of exceedance in 50 years) and confirms subduction-zone earthquake significance. Figure 1(e) presents the contributing factors of specific earthquake categories, revealing that interplate/intraplate earthquakes without specified source faults for the Philippine Sea plate have a significant influence in the short-period range, whereas those for the Pacific plate, Sagami Trough earthquakes, and Nankai Trough earthquakes have a significant influence in the long-period range.
We anticipate that the continued development of PSHA response spectra will contribute to the evaluation of structural responses for different exceedance probabilities and the implementation of seismic designs. The ERC is actively working toward effectively communicating PSHA response spectra results in ways that meet the needs and expectations of users for effective implementation.