【作者】 瞿辰；

【导师】 朱介寿； 曹家敏；

【作者基本信息】 成都理工大学 ， 地球探测与信息技术， 2003， 硕士

【摘要】 本研究利用了亚洲、部分欧洲及西太平洋地区台网58个数字地震台，搜集了42°E-170°E，24°S-66°N范围内近万个地震事件，并从中挑选出1982-2001年间的震级绝大部分都在5.0～7.0之间，震源深度小于100km的704个事件。经过筛选，共得到周期在8—400s之间5007条质量较高的瑞利面波频散曲线。用面波频散进行反演，提高测定精度(大范围模型为2°×2°，精细模型按1°×1°)，建立全国及七个分区(菲律宾海、日本海、华北、华南、西北、青藏、南海)地壳上地幔高分辨率三维S波速度图像。 高分辨率速度成像表明，从上地壳到70km深，在东亚东部及西太平洋边缘海地区均为高速分布，西部以青藏高原为中心呈极低速分布。沿大兴安岭—太行山—武陵山有一条十分清晰的速度分界线(与我国东部重力梯级带位置吻合)。自地中海经土耳其、伊朗、喜马拉雅山到缅甸、印尼群岛的特提斯汇聚碰撞带，显示为低速异常链。 从85km至250km深，在东亚东部及西太平洋边缘海，自北向南显示出一条宽约2500-4000km，长约8000km的巨型低速异常带。沿日本伊豆、小笠原群岛、马里亚纳海沟出现高速异常带。西部地区包括印度板块、哈萨克斯坦、青藏、塔里木及扬子地块为高速异常分布。深度300-400km的平面图上，速度差异幅度不大，塔里木至扬子地块仍然显示为高速分布。 大体以东经110°E为界，东西两部份岩石圈与软流圈的结构有着巨大的差异。此界线以西主要是印度板块与欧亚板块碰撞引起的岩石圈汇聚增厚区，东部则主要是由于软流圈上涌(地幔热物质上升)引起的岩石圈拉张减薄区。西部地区岩石圈比东部大约厚100km。西部地区软流圈一般不发育，而东部地区软流圈比西部厚100-140km。西部地区岩石圈的S波速度比东部要高0.2-0.25km/s。在地幔压力条件下，东部岩石圈下部的温度比西部要高出300-400℃。 东亚的东部及西太平洋边缘海地区，与西部地区的演化和动力学过程是完全不同的。古新世印度与欧亚大陆的碰撞汇聚，岩石圈板片以低角度下插到青藏高原之下，引起高原隆起和地壳增厚，西部地区成为岩石圈汇聚区。中生代中晚期东亚大陆东缘岩石圈解体，软流圈物质上涌，岩石圈减薄张裂，形成巨型低速带，并演化为东亚裂谷系。更多还原

【Abstract】 This paper deals with the high resolution surface wave tomography in china and its adjacent land and sea areas .subareas (Tibet, South China, North China, Northwest China, South China Sea, Japan Sea, Philippines Sea) as well as. 704 events(7.0 > M > 5.0) recorded at 58 digital seismic stations form CDSN,GSN,GDSN and GEOSCOPE network in Eurasia and west Pacific regions were used in this paper. Five thousands and sever hundred accurate surface dispersion curves were selected and employed for inversion. The high resolution 3-D shear wave velocity images in this area was constructed by inversion dispersion and show a notable lateral variation in the crust and upper mantle.The images of S wave velocity indicate that from the upper crust to the depth of 70km, the high velocity is displayed in the region of eastern part of East Asia and West Pacific marginal seas, in contrast, extremely low velocity is in the Qinghai-Xizang plateau and its surrounding areas. There exists a boundary of velocity decrease along the Mountain belt from Da-Xingganling to Taihangshan, Wulinshan, which coincides with the gravity gradient belt in NNE-SSW trend in East China. The low velocity anomaly chain is located along the convergence belt of Tethys from Mediterranean Sea, Turkey, Iran, Himalayan orogens, Burma, Indonesian Islands.The evolution and geodynamic process is so different between the eastern part and western part of the East Asia and West Pacific marginal seas by the boundary of longitude 110°E. The western part is the thickening convergent lithosphere caused by Indian subcontinent collided with the Eurasian continent, and the eastern part is disassembly causing the lithosphere thinning and extension arising from intrusion of asthenospheric material.更多还原