Research On ShakeMaps And Shaking Intensity Based On Records Of Monitoring Network

For a long time, earthquake emergency and rescue works in our country are depending mainly on site investigations. There are not enough monitoring stations in China mainland because of lack of money and immature technologies. Subjective factors are always involved in site investigations although many experienced experts take the work. Furthermore, a site investigation requires much time and is unfavorable to the whole rescue work. In this paper, the author draws lessons from ShakeMaps used in southern California and in Taiwan region. Considering the actual situations of our country, the author proposes a new method that could make full use of information recorded by monitoring network available nowadays. It could also take the attenuation effects into accounts. The main achievements of this study have been summarized as follows:1. Earthquake location and magnitude determination is a basic problem in seismology. Based on voronoi theory, the author use grid-search method to locate the epicenter of Shunchang earthquake happened in Mar 13th, 2007, and Yongchun earthquake happened in Aug 29th, 2007. Results show that this method has certain precision and can be used in epicenter rough location. The author proposes a method of just use the first station's magnitude to estimate the final magnitude. We study the feasibility and efficiency of this method, and find that if earthquakes happening in inner monitoring net, final magnitude can be acquired in 10 seconds, and for outer net earthquakes this process can be done in 1 minute.2. ShakeMap is a fast way to acquire the damage information after earthquakes. It is impossible to use methods in southern California indiscrimi- nately as monitoring stations distributed sparsely in China mainland. As a result, the author try to make full use of information collect by current stations, and propose a new method that can calculate a certain point's time history just use nearby stations'records. The author derivate a formula of just use three stations'information, then verify it use records collected in Shunchang earthquake. Analyses show that this method has certain precision and could satisfy expected requirements. Subsequently, the author grid Fujian zone and calculate time history of every node use method mentioned above. For every 1 second interval, we can get a peak value distribution (PGA or PGV) map, then we play these maps continuous, in this way, we create our "Shake Map". Most people will easy understand this new form as it coincidence with their common sense. In addition, the author list out peak value of different directions (horizontal and vertical), for professionals these must be more important. The author regressed attenuation relationship of peak value calculated and peak value get from real record respectively. Results show that these two relationships are very close and peak values produced by calculation are depends on real records. These analyses confirm that this method not only takes the attenuation effects into account, but also it could remedy the sparsely distributed stations'defect. In a word, it's a good method.3. Physical standard of earthquake intensity is a hot topic in seismology field. In this paper, the author list different standards or calculation methods used in America, Japanese, Taiwan region and China mainland. Then, we compare intensity assess form used in Taiwan region and intensity assess form used in China mainland carefully. Findings are as follows: these two forms have similar description in macro phenomenon caused by earthquakes. Intensity assess form used in Taiwan region have specific PGA definition for different grade, however,â… -â…£levels in China assess form are wanting. Then the author take the 0-3 PGA boundary in Taiwan assess form as a complement of China mainland intensity assess form and redefine a new assess form. It is impossible to consistent with other forms as we just consider one aspect of seismic damage. In order to differentiate from others, we name it"shaking intensity"and hope it become an objective physical quantity. Subsequently, the author analysis shaking intensity distribution of Shunchang earthquake, Yongchun earthquake and Gutian earthquake (happened in Mar 6th, 2008) respectively. Result shows that this form could take the intensity attenuation effects caused by ground motion attenuation into account reasonable and accordance with site investigation results. As a simple application of shaking intensity, the author collect 72 large and middle reservoirs'information in Fujian province, then calculate the time history of each place based on method mentioned in chapter 3 to assess it's shaking intensity and compare with seismic fortification intensity in order to make sure if it could cause dangerous. All these research prove that our method has a simple and quick feature and can be used in some place.In the conclusion part, the summary is given.