Study On Earthquake Emergency Handling Effective Early Warning Time Based On PGA

With the coming era of information technology, the earthquake early warning technology is developing fast, which has been popularly used in the worldwide countries such as the America, Japan, Mexico and China as a great contribution to the earthquake mitigation and loss reduction. It’s a hot issue how to analyze the effective earthquake early warning time in the study field of earthquake early warning. Due to the randomness and uncertainly of earthquake, it becomes difficult to get the real ground motion records upon our real demand. Thus, the attention is raised on the ground motion synthesis which has been developed some useful methods such as the theoretical and empirical Green Function method, the random method and the hybrid method. Those methods promote the development of this research field itself and provide an effective tool on the study of the earthquake early warning as well.As a typical example, in this paper, the stochastic finite-fault method in ground motion synthesizing is used to investigate the effective earthquake early warning time in the area of Capital Circle including three aspects as follows:(1) Simulate the ground motion using the stochastic finite-fault method. Taken the Mw6.7January17,1994Northridge, California, earthquake and the Ms6.0October27,2001Yongsheng, Yunnan, earthquake as examples, the feasibility and validity of the stochastic finite-fault method in simulating the ground motion using at home and abroad is verified. On the basis of a summary of the potential seismic source zone and fault information in capital encircles, the ground motion of each zone with the different magnitude range is simulated, and the predicted PGA contours are delineated subsequently.(2) Compute the earthquake early warning time. It is summarized that the influencing factors on earthquake early warning products include the environment changing, parameters selection, time to process information, alert information issue, false alarm and missing report and so on. Suggestions about classification of earthquake early warning in China are put forward based on the principle of earthquake early warning system and classification of the disasters. The earthquake early warning time of capital encircles at every site for every potential seismic source zone is computed based on the method introduced in this paper. Distribution maps of the earthquake early warning time for every potential seismic source zone are drawn. (3) Analyze the effective early warning time in the seismic emergency handling. Taken the high-speed rail as an example, two important issues on the selecting criteria of the threshold and the layout of monitoring stations are summarized by means of an introduction of the development of the high-speed rail in China and abroad and its construction conditions of earthquake early warning system. Then some suggestions are given about these two issues. The predicted PGA contours and the distribution maps of the earthquake early warning time of the capital encircles are superimposed. Consequently it is created that the figures about the effective early warning time of the seismic emergency handling.As a result, the ground motion simulation and the earthquake early warning time of capital encircles enhance the study of ground motion and development of the earthquake early warning system in capital encircles. In addition, the superimposed graphs of predicted PGA contours and earthquake early warning time in capital encircles have a great contribution on the fast disaster evaluation while the earthquake happens and the later decision-making of the emergency measurement. The following work will be expected to join the high-speed railway lines in capital encircles into the above study and obtain the real effective early warning time of the seismic emergency handling.