| 青藏高原东北缘地壳三维速度结构 |
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| 引用本文： | 周民都,张元生,石雅鏐,张树勋,范兵.青藏高原东北缘地壳三维速度结构[J].地球物理学进展,2006,21(1):127-134. |
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| 作者姓名： | 周民都 张元生 石雅鏐 张树勋 范兵 |
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| 作者单位： | 1. 中国地震局地震预测研究所兰州基地，兰州 730000;2. 中国地震局兰州地震研究所，兰州 730000 |
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| 基金项目： | 国家重点基础研究发展规划项目(95-13-02-02)资助，中国地震局兰州地震研究所论著编号:LC20060001 |
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| 摘 要： | 本文用1980—2000年M≥1.5的2 032个天然地震事件的38 052个〖AKP-〗、〖AKS-〗、Pm、Sm、Pn和Sn震相到时及人工地震测深给出的Moho面形态资料，利用地震层析技术反演了32°~40°N, 100°~108°E区域内地壳地震波速度结构.从层析成像图象中可以得到，本区的地壳可分成4个层位.第1层（埋深约在0~3 km）为沉积层， 速度梯度约为0.2 s-1；第2层（埋深约在3~17 km）为上地壳, 其顶部速度梯度约为0.1 s-1, 下部速度横向变化较大且存在低速块体；第3层（埋深约在17~36 km）为中地壳， 速度梯度约为0.03 s-1；第4层（埋深约在36 km—Moho）为下地壳, 是一个契形层，总的趋势是西厚东薄，青藏高原较厚逐渐向鄂尔多斯地块和扬子准地台方向变薄，各处的地震波速度梯度不尽相同.
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| 关 键 词： | 青藏高原东北缘 层析成像 地壳三维速度结构 遗传算法 |
| 文章编号： | 1004-2903（2006）01-0127-08 |
| 收稿时间： | 2005-06-10 |
| 修稿时间： | 2005-08-10 |
Three-dimensional crustal velocity structure in the northeastern margin of the Qinghai-Tibetan plateau |
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| ZHOU Min-du,ZHANG Yuan-sheng,SHI Ya-liu,ZHANG Shu-xun,FAN Bin.Three-dimensional crustal velocity structure in the northeastern margin of the Qinghai-Tibetan plateau[J].Progress in Geophysics,2006,21(1):127-134. |
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| Authors: | ZHOU Min-du ZHANG Yuan-sheng SHI Ya-liu ZHANG Shu-xun FAN Bin |
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| Abstract: | This paper presents the three-dimensional crustal seismic wave velocity structure in the region 32°~40°N, 100°~108°E reconstructed through seismic tomographic inversion. We use 38 052 arrival time data of 〖AKP-〗, 〖AKS-〗, Pm, Sm, Pn and Sn phases recorded from 2 032 earthquakes with M≥1.5 occurred from 1980 to 2000 and the Moho interface topography data from deep seismic sounding. The 3-D tomographic image clearly reveals that the crust structure of this region consists of four layers. The top layer (about 0~3 km) has a velocity gradient about 0.2 s-1 that corresponds to the sediments. The second layer (about 3~17 km) is the upper crust with a velocity gradient about 0.1 s-1 at top and relative large lateral velocity variation as well as lower velocity blocks at bottom. The third layer (about 17~36 km) is the middle crust with velocity gradient 0.03 s-1. The lower crust forms the fourth layer (about 36 km-Moho), which is thick in the west and thin in the east. The thickness of this layer gradually reduces from the Qinghai-Tibetan plateau to the Erdos platform and the Yangtze paraplatform with different velocity gradient at different location. |
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| Keywords: | Northeastern margin of Qinghai-Tibetan plateau Seismic tomography 3-D crustal structure of seismic velocity Genetic algorithm |
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