The study area of this article covers the continental shelf of the East China Sea and the Okinawa Trough. Tectonically, the area is the seaward extension of the eastern China mainland, consisting of the East China Sea shelf basin, the Diaoyudao islands uplift-fold zone, and the Okinawa Trough Basin developed in Cenozoic. Lying at the conjunction between the Eurasian and Philippine plates, the neotectonic movement since Miocene and resultant geologic structure of this area are complicated and peculiar. Based on pervious data and studies, this paper makes a systematic and in-deep analysis to the features of the neotectonic movement in this region, involving geomorphology, geological structure, magma activity and earthquakes. Then, the dynamic conditions for the neotectonic movement of the study area are discussed.
Neotectonic movement of East China Sea started from middle Miocene and the mechanism of the tectonic stress field changed from sinistral transtension to sinistral transpression. The neotectonic movement in this area is inhomogeneous, with the continental shelf basin inclining and subsiding slightly to the southeast, the Okinawa trough dominated mainly by crustal active rifting, and the Diaoyu Islands fold belt characterized by lateral compressive bending uplift. The active faults, mainly trending NNE and NE, are dominantly distributed in the continental shelf basin, especially in the Okinawa trough. Magmatism and earthquake activity are also mainly distributed in the east of the continental shelf basin, especially in the Okinawa trough. The neotectonic movement in East China Sea is co-influenced by the back arc mantle uplift which is caused by the subduction of the Philippine plate beneath the continental shelf of East China Sea and results in the NW-SE rifting of Okinawa trough, and the southeastward movement of South China block which is pushed by the lateral extrusion of eastern Tibet.

Two kinds of site classification methods commonly used in earthquake engineering are analyzed in this paper.One is standard methods stipulated in seismic codes,and used to determine the site effects on seismic parameters for the seismic resistance of structures,the site classification methods and site indexes in seismic codes of China,United States,Europe and Japan are presented,and the problems about site index are discussed,such as the calculation method and depth of shear wave velocity,the choice of initial layer,the grade of overburden thickness,etc.Then some suggestions are put forward for the new generation of seismic code in China.The other kind of site classification methods is used to predict site effects on a large scale for a regional seismic hazard prediction.The popularly studied methods based on geology,topography and geomorphology are described in detail.The common character of this kind of methods is to find an easily obtained macro index,and to summarize the rules between the macro index and the site index in seismic codes(shear wave velocity in most cases),and then the regional site category zonation can be delineated.The response spectrum methods of ground motion are also presented here,such as RSS(Response Spectral Shape)and HVSR(Horizontal-Vertical Spectral Ratio),they can be used in areas with abundant ground motion records.Finally the advantage,limitation and applicable scope of these methods are discussed.

The assessment of regional seismotectonic environment is very important for seismic safety evaluation of engineering sites, and it is essential to compile a regional seismotectonic map for the region where engineering site is. For reusing the work products of seismic safety evaluations in past years and lessening repetitive hard work, it is a valuable work to build a database of regional seismotectonic map for regions where a number of seismic safety evaluation of engineering sites have been accomplished.In the past few years, we have accomplished many projects of seismic safety evaluation of engineering sites in southwest China. Combining with the work of other groups, it is possible to build the database of regional seismotectonic map in southwest China.As a useful desktop mapping software and GIS, MapInfo provides a powerful solution for mapping geographic information. It is selected as the platform to build our database. In database design of GIS, the spatial information and attribute information are usually separated considering the large quantity of data, efficiency and convenience in analysis and query of spatial information. Separate design of spatial database and attribute database is also convenient for extension and share of database. For meeting the requirement of seismic safety evaluation code, the regional seismotectonic map must include: 1) age, type and kinetic characteristic of faults in Qh; 2) active fault segment; 3) range and sediment thickness of active basin in Qh; 4) characteristic of modern tectonic stress field; 5) the epicenter distribution of earthquakes M≥4³/₄. This decides that the database of regional seismotectonic map is composed of multiple layers, multiple basic types and multiple relational tables.The database of regional seismotectonic map of southwest China on MapInfo platform is built by using the separate design of spatial database and attribute database with the structure of multiple layers, multiple data types and multiple relational tables; and basic function of the database and output method of regional seismotectonic map is showed in the end.