青藏高原东南缘多尺度重力场及构造含义

Multi-Scale Gravity Field of Southeastern Tibetan Plateau and its Tectonic Significance

本文基于EGM2008重力场模型研究了青藏高原东南缘均衡重力异常和多尺度的布格重力异常特征,以鲁甸和景谷地震为例,认识其深部构造环境和动力学过程,为该区域的构造运动和地震孕育环境研究提供依据。结果表明,研究区布格重力异常和均衡重力异常与地质构造格局相关性较好,川滇地块剧烈的区域布格重力异常和非均衡状态与其强烈的地壳变形、断裂及地震活动密切相关。强震多分布在断裂带两侧重力异常的过渡地带和高梯度带,断裂带两侧横向和垂向的显著介质密度差异是强震孕育的深部构造背景。布格重力异常和均衡重力异常揭示的鲁甸、景谷震源区深浅差异性的重力异常特征,暗示鲁甸和景谷地震孕震环境的不同。

On August 3 and October 7,2014,the Ludian M_(S)6.5 earthquake and Jinggu M_(S)6.6 earthquakes respectively occurred in Yunnan,China.Based on the EGM2008 gravity field model,this paper studies the Isostatic gravity anomaly and multi-scale Bouguer gravity anomaly of the southeastern Tibetan Plateau.The deep tectonic environment and dynamic process of the Ludian and Jinggu earthquakes are analyzed and recognized,which provide a deep understanding of tectonic movement and earthquake inoculation environment in this region.The Bouguer gravity anomaly and the Isostatic gravity anomaly in the study area are correlated well with the geological structure,and the severe regional Bouguer gravity anomalies and the non-equilibrium state of the Sichuan-Yunnan block are closely related to its strong crustal deformation,fracture and seismic activity.The strong earthquakes in the study area are mainly distributed in the transition zone and high gradient zone of gravity anomaly on both sides of the fault zone,and the significant difference of medium density on both sides of the fault zone is the deep tectonic background of strong earthquakes.The difference of the deep and shallow density structure of Ludian and Jinggu hypocentral region being revealed by Bouguer gravity anomaly and Isostatic gravity anomaly indicates,the seismogenic environment difference between Ludian and Jinggu earthquakes.