The Assessment Of Regional Crustal Stability In Tangshan

With looking after other factors and following the principle that the tectonic stabilityresearch is the focus of the assessment and research of regional crustal stability, this thesishas quantitatively evaluated the crustal stability of Tangshan applying the fuzzymathematics comprehensive assessment method.Through collecting many datas, the faults of the Tangshan researched and exploredsystemically, and initially defines that there are 10 main faults in Tangshan. Based on this,the thesis also researches systemically about the deep crustal structure, Cenozoic andrecent tectonic activity, the crustal surface structure and rock-soil mechanical property, andseismic activity and risk.After having scientifically analyzed the main factors that influence the crustal stability,taking the main faults that control the framework of Tangshan as the key and adopting4km×4km as a unit. So, there are 6 main genes in this paper applying the fuzzymathematics comprehensive assessment method.The area of Tangshan is 13472km~2. The result of evaluation shows that the area ofrelatively instable, less instable belts, and the sum of the two respectively is 16.6, 37.9, andthe area of the relatively less stable, stable of the two respectively is 27.3, 18.2 .So,generally speaking, The percentage of relatively less stable is a little more than that ofrelatively stable of Tangshan. Furthermore, there are 175 relatively instable belts inTangshan, and their position is corresponding to the faults. All these relatively instablefault belts are deep or active fault, so, this shows that deep fault and active fault plays a keyrole in influencing the crustal stability of Tangshan. Moreover, the result of comparing thefigure of assessment with the seismic risk zone figure of the Tangshan shows that the mostof the relatively instable and less instable belts are within the risk areas of earthquake inTangshan forecasted by Hebei Earthquake Department. This shows that strong seismicactivity and seimic risk area is a very important factor to the crustal stability of Tangshan.