试论长江三峡地区地震活动的构造基础和活动趋势

根据长江三峡地区的阶地和夷平面的调查研究,该地区自新第三纪以来,构造运动具有缓慢抬升的特点。各个地震带上所发生的一系列中等强度的浅源地震是由于长期的抬升、强烈的侵蚀切割、以及由剥移所造成的均衡调整和不同地块体之间均衡运动的差别所致。估计未来本地区不会发生6级以上的地震。但对秭归盆地的深部结构和新构造运动特征需要作进一步的调查研究

A PRELIMINARY DISCUSSION ABOUT THE TECTONIC BACKGROUND OF SEISMICITY IN CHANGJIANG THREE GORGE AREA AND ITS FUTURE TREND

Based on the studies of terraces and peneplains of the Changjiang three Gorge area,it is confirmed that the tectonic movement in this area is characterized by the slow uplift as a whole since the Neogene period. A series of earthquakes with moderate intensities and shallow foci dispe- rsed along various seismic belts are due to a long-standing uplift,intense erosion,isostatic adjustment for stripping,as well as the difference in isostatic movement between the adjacent masses.It is estimated that large scale earthquakes may not occur in the investigated area in future. However,it is necessary to bo further investigations of deep structure and neotectonic feature in Zigui Basin.