Seismic Rhythm. in Coastal Area of Souilieastera China and Its Application ia Evaluatioa of Seismic Seismic Area

Coastal area of southeast China belongs to South China seismic region which has weak seismicity with a low freq uence. In this paper, coastal area of southeast China we study is the highest seismicity area i.n South China seismic region. In his-tory, many earthquakes have ever occurred in this area with a magnitude ۷ or ۸. Therefore, it is important to analyze the features of seismicity and estimate the seismic hazard of this belt. Since this area is economic development zone with de-veloped economy and densely populated, more importance is the evaluation of seismic hazard and seismic hazard zoning. lit evaluation of seismic hazard, and study of seismic regularity in this area are some of the most important work. While. studing the features of seismicity in this area, we find that earthquake distribution in space hits an apparent rhythm and the zoning of seismic density and the seismic time sequence in inner and outer belt are complement each other. These features are very reliable in prediction of seismic hazard and seismic hazard area. The pur-pose of this paper is to analyze the seismic features mentioned above, then discuss their application in evaluation of seismic hazard area. (۱ ) Distribution of seismicity in space and analysis ۰۱.st:۴۴۱۱۱w . time sequence ۱, Span of the study region and division of the seismic belt This study region includes both Guangdong and Hainan Provinces, west of Fuzhou in Fujian Province, Y ulin, WuLhou, Linshan iii the eastern Guangxi Pio v-ince and their surroundings, and Shaowu. Ganzhou and ۱۱ uichang in Jiangxi Prov-ince. this region is about ۱۵۰n km in length and ۵۱۱ukin in width, trending NE, nearly like a rectangle. According to the record, there are ۱۸ earthquakes with ۱ magnitude of more than ۶. ۳ earthquakes of which arc of magnitudes of ۷— ۷-- one earthquake, of a magnitude of ۸. Earthquakes with magnitude of ۷ and ۸ are mainly distributed along the coastal area, some are located between Shantou and Fuzhou, others in liaikuu area. Earthquake*, with a magnitude of ۶ are nearly well distributed along the coastal area. There are also some earthquakeswith a magni-tude of ۶, occurring in the inland including the X in Fengjiang reservoir earthquake in ۱۹۶۲. According to the features of geological tectonics and seismicity, we could get two seismic belts in this study region(Fig.۱), which respectively are outer belt in coastal area of sou thestern China (Briefly called outer belt) and inner belt in the same above mentioned area (Briefly called inner belt). Seismicity of outer belt is stronger than that of inner belt. All of earthquakes wish a magnitude of ۷ and ۸ occurred in the outer belt, occurrence of earthquake with magnitude ۶ is higher in the outer belt. There arc total ۱۰ earthquakes with a magnitude of ۶ occurring in