The Crustal Isostatic State of Sichuan-Yunnan Region and Its Relationship with Regional Earthquakes
The Crustal Isostatic State of Sichuan-Yunnan Region and Its Relationship with Regional Earthquakes
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发表时间：
2015
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通讯作者：
Jiang Yongta
中科院分区：
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作者：
Jiang Yongta
利用地壳1.0模型，分析了川滇地区上地壳厚度结构和莫霍面结构。然后根据艾里均衡理论计算了区域均衡莫霍不连续。利用均衡面与实际莫霍面的差异，研究了川滇地区的地壳均衡状态。对比上地壳厚度分布图与区域地震深度分布图，发现区域地震主要发生在上脆性地壳。地壳均衡特征明显表明四川盆地处于均衡状态。而龙门山断裂带则处于均衡外状态，是川滇地区最显著的不平衡区，其北侧为正平衡（+6km），南侧为负平衡（-6km），西南侧为正平衡（+6km）。这可能反映了龙门山断裂带深部地壳物质正经历着剧烈的分异、调整和强烈的能量交换。
Using the model CRUST 1.0,we analyze the structure of upper crust thickness and the moho discontinuity in Sichuan-Yunnan region.Then we calculate the regional isostatic moho discontinuity based on the Airy isostatic theory.With the difference between the isostatic and the real moho discontinuity,we study the state of crustal equalization in the Sichuan-Yunnan region.Comparing the map of upper crust thickness with the depth distribution diagram of regional earthquakes,we found that regional earthquakes mainly occurred in the upper brittleness crust.The crustal isostatic apparently shows that the Sichuan basin is in an isostatic state.However,the Longmen mountain's fault zone poses a state which is out of the isostatic,and represents the most remarkable disequilibrium area in Sichuan-Yunnan region,whose north side presents positive equilibrium(+6km),south side presents negative equilibrium(-6km)and southwest side presents positive equilibrium(+6km).All of this possibly reflects that the deep crust material beneath Longmen Mountain's fault zone is undergoing a dramatic differentiation,adjustment and intense exchange of energy.