Abstract: The eastern Himalayan syntaxis is located on the leading edge of Indian-Eurasian plate collision, and the uplift rate of Namche Barwa area is higher than that of the peripheral zones, which is considered as the core position of the eastern Himalayan syntaxis(Uplift Center).It is indicated according to the recent regional earthquake observation results that, the seismic activity is poor in the area of Namche Barwa, but with strong seismic activity in its southeast region. In order to study the current geodynamical characteristics of the eastern Himalayan syntaxis, the elevation frequency distribution and hypsometry curve of Namche Barwa area, its northwest and southeast as well as the northeast Assam area is analyzed using DEM data. It is shown according to the result that, the Namche Barwa area is in the mature stage of erosion and the regional tectonic uplift and denudation are in the highly balanced status. Influenced by plateau-climate weather effect, the denudation of this area is relatively poor, which indicates that the uplift of the Namche Barwa area is relatively slow at present. The geomorphology in the northwest and southeast as well as in northeast Assam is in young evolutionary phase, belonging to erosive infancy, and the geomorphology of northeast Assam is closer to the early stage of infancy. The geomorphic evolution stage on northwest side reflects that the regional erosion is poor and it still belongs to plateau-climate area; Influenced by south subtropical monsoons, there is rich rainfall in the area from southeast Namche Barwa to Assam area, and this area still belongs to erosive infancy, even the geomorphic development degree of northeast Assam is lower as it suffers from strong erosion effect, which means that the tectonic uplift in east Namche Barwa is very intensive, and the northeast Assam has the highest uplift rate. It is considered according to the research that, under the mode that India Plate moves towards the north at present, the core position of the eastern Himalayan syntaxis(Uplift Center)moves towards the southeast, and the new core position may be located in northeast Assam, where there is intensive regional tectonic uplift with high potential of great earthquake.

Key words: eastern Himalayan syntaxis, DEM data, elevation frequency, hypsometry, seismic activity

摘要： 喜马拉雅构造结位于印度与欧亚板块碰撞的前缘，其内部的南迦巴瓦峰地区隆升速率大于周边区域，被认为是东构造结的核心部位（隆升中心）。近期区域地震观测结果表明，南迦巴瓦峰地区地震活动较弱，而其东南侧区域地震活动频繁。为了研究东构造结地区目前的地球动力学特征，文中利用DEM数据分析了南迦巴瓦峰及其西北、东南两侧和阿萨姆东北部区域的高程频率分布及面积高程积分曲线。结果显示，南迦巴瓦构造结区域属于侵蚀的壮年期，区域构造隆升和剥蚀作用已经达到高度平衡的状态，受到高原气候影响，该地区剥蚀作用相对较弱，表明南迦巴瓦构造结区域目前隆升相对缓慢。西北、东南侧以及阿萨姆东北部区域地貌均表现为年轻的演化阶段，属于侵蚀的幼年期，阿萨姆东北部地区地貌更接近幼年期早期阶段。西北侧的地貌演化阶段反映了区域侵蚀能力较小，仍属于高原气候区；南迦巴瓦峰东南侧至阿萨姆区域受到南亚热带季风的影响，降雨充沛，遭受强烈的侵蚀作用，区域尚属于侵蚀的幼年期，且阿萨姆东北部地貌发育程度更低，表明南迦巴瓦构造结以东地区构造隆升非常强烈，隆升速率最大的地区位于阿萨姆东北部。文中认为，在现今印度板块向N推进的模式下，喜马拉雅东构造结核心部位（隆升中心）向SE发生了偏移，新的核心部位可能位于阿萨姆东北部区域，该地区隆升强烈，构造应力积累发生大地震的可能性较大。

关键词: 东喜马拉雅构造结, 高程频率, 面积高程积分, 隆升中心, 地震活动