重复绝对重力测量观测的滇西地区和拉萨点的重力变化及其意义

根据近年来在滇西地区和西藏拉萨绝对重力点上的一些新的绝对重力重复观测结果 ,对1990年以来在这些点上绝对重力重复观测结果进行了分析. 滇西地区的5个绝对重力观测 点的近10年的重复观测结果表明，大部分观测时段没有出现与地球动力学事件有关的重力变 化，只有丽江和洱源2个绝对重力观测点的观测结果显示丽江地震前后有变化. 为了研究该 重力变化的原因，本文正演模拟了出现重力变化期间丽江地震同震位错引起的重力变化，模 拟结果与实际观测结果有较好的一致性. 西藏拉萨近10年以来的重复观测结果给出了拉萨点 的绝对重力值以-1.82±0.9×10-8m·s-2·a-1速率下降，这从重力学 的角度反映出青藏高原的隆升. 对拉萨点的重力变化机制进行了探讨，根据印度板块与欧亚 大陆俯冲模型计算的拉萨点重力变化速率与观测到的重力变化速率较一致，表明现今拉萨地 区重力变化是由于印度板块与欧亚大陆俯冲所引起. 根据印度板块向欧亚大陆俯冲的位错模 型计算的拉萨点的重力变化与地表垂直位移的关系，将重力变化转换为拉萨点的隆升速率为 8.7mm/a. 

Gravity change detected by repeated absolute gravity measurements in the western Yunnan and Lhasa, China and its implication

The observed results of repeated absolute gravity measurements since 1 990 at the western Yunnan and at the Lhasa stations are analyzed, together with some new observed data at these stations. The repeated observation results durin g about 10 years at five stations in the western Yunnan indicate that no signif icant gravity changes related to the geodynamical events were observed in most o bservation epochs. Significant gravity changes have been detected at Lijiang and Eryuan stations in the western Yunnan before and after Lijiang earthquake (M S=7.0). We modeled the gravity changes caused by the co seismic dislocation during the Lijiang earthquake, that are in good agreement with the observed data . The gravity changes with time about 10 years at Lhasa station have a slop of -1.82±0.9×10-8m·s-2·a-1, indicating that Qinghai Xizang p lateau has an uplift. The mechanisms of gravity changes at Lhasa were investigat ed. We calculated the gravity change rates based on the model of India plate to Eurasia subduction. The computed gravity change rate at Lhasa is in