文中基于D-InSAR技术,利用欧空局C波段升降轨哨兵SAR数据,获取了2021年5月22日青海玛多M_(W)7.3地震的InSAR同震形变场,并对同震形变的空间特征、量级和断层破裂的分段性进行了分析。哨兵卫星的高质量观测数据清晰地描绘了玛多地震的地...文中基于D-InSAR技术,利用欧空局C波段升降轨哨兵SAR数据,获取了2021年5月22日青海玛多M_(W)7.3地震的InSAR同震形变场,并对同震形变的空间特征、量级和断层破裂的分段性进行了分析。哨兵卫星的高质量观测数据清晰地描绘了玛多地震的地表破裂迹线,地表破裂长度约210km。为了进一步认识玛多地震断层深部的同震滑动分布特征和发震断层几何性质,基于升、降轨InSAR形变场及精定位余震数据确定的断层几何反演了同震滑动分布,并基于同震库仑应力变化分析了本次地震对周边区域的应力扰动。结果表明,玛多M_(W)7.3地震发生在巴颜喀拉块体内部的一条次级断层上,且与东昆仑断裂带的主断裂近平行,结合野外考察、地质资料和InSAR地表破裂迹线确定的发震断层为昆仑山口-江错断裂。玛多地震产生的同震形变场空间影响范围广,形变场的长轴呈NWW向,升、降轨观测的形变量符号相反,结合哨兵数据的观测几何确定发震断层的运动性质以左旋走滑为主。基于升、降轨InSAR数据得到的最大视线向(Line of Sight,LOS)形变量约为0.9m。同震滑动分布模型显示,整体上断层的走向为276°,倾角为80°,倾向NE,最大滑移量约为6m,平均滑动角为4°,矩震级为M_(W)7.45,地震主体破裂发生在0~10km深度范围内,同震破裂至地表,与野外考察所观测到的广泛分布的同震地表破裂带一致。以玛多-甘德断裂为接收断层的同震库仑应力模型显示,玛多地震在玛多-甘德断裂西段附近产生了明显的应力降,表明玛多地震释放了玛多-甘德断裂的库仑应力,导致后者的地震危险性可能大大降低;而在玛多-甘德断裂和昆仑山口-江错断裂交叉的区域存在应力加载效应,但考虑到玛多地震的余震会释放多余的能量,该区发生较大地震的危险性可能降低。以东昆仑断裂为接收断层的同震库仑应力模型显示,玛多地震在�展开更多
The Wenchuan earthquake of 12 May 2008 is the most destructive earthquake in China in the past 30 years in terms of property damage and human losses. In order to understand the earthquake process and the geo-morpholog...The Wenchuan earthquake of 12 May 2008 is the most destructive earthquake in China in the past 30 years in terms of property damage and human losses. In order to understand the earthquake process and the geo-morphological factors affecting the seismic hazard, we simulated the strong ground mo-tion caused by the earthquake, incorporating three-dimensional (3D) earth structure, finite-fault rupture, and realistic surface topography. The simulated ground motions reveal that the fault rupture and basin structure control the overall pattern of the peak ground shaking. Large peak ground velocity (PGV) is distributed in two narrow areas: one with the largest PGV values is above the hanging wall of the fault and attributed to the locations of fault asperities and rupture directivity; the other is along the north-western margin of the Sichuan Basin and caused by both the directivity of fault rupture and the ampli-fication in the thick sediment basin. Rough topography above the rupture fault causes wave scattering, resulting in significantly larger peak ground motion on the apex of topographic relief than in the valley. Topography and scattering also reduce the wave energy in the forward direction of fault rupture but increase the PGV in other parts of the basin. These results suggest the need for a localized hazard as-sessment in places of rough topography that takes the topographic effects into account. Finally, had the earthquake started at the northeast end of the fault zone and ruptured to the southwest, Chengdu would have suffered a much stronger shaking than it experienced on 12 May, 2008.展开更多
青藏高原东南部边缘的程海-宾川断裂带是一条正断与左旋走滑运动兼具的复合型活动断裂,起着调节青藏高原内部物质向东挤出的重要作用,并控制着区域的主要强震活动.基于GIS(Geographic Information System)技术,利用遥感影像和DEM(Digita...青藏高原东南部边缘的程海-宾川断裂带是一条正断与左旋走滑运动兼具的复合型活动断裂,起着调节青藏高原内部物质向东挤出的重要作用,并控制着区域的主要强震活动.基于GIS(Geographic Information System)技术,利用遥感影像和DEM(Digital Elevation Model)数据提取该区的关键构造地貌信息,对其第四纪分段活动性及特征进行了分析探讨.结果表明,程海-宾川断裂带的第四纪活动具有明显的分段性及空间差异性.其北段的金官-程海盆地主边界断层以正断层活动性质为主,并具有整个断裂带上最高的垂直活动速率;中段的期纳断裂以左旋走滑运动为主,且具有最高的走滑活动速率;南段宾川盆地东缘边界断裂也以正断层活动为主,但垂直活动速率略低于北段.总体上看,程海-宾川断裂带第四纪期间的垂直活动性由北往南降低,水平走滑活动性由中段往南北两端降低.在活动强度方面,程海-宾川断裂带百万年尺度的长期活动速率一直保持着较为稳定的状态,垂直活动速率主要集中在0.09~0.69mm/a,水平走滑速率在0.20~1.40mm/a.整体而言,程海-宾川断裂带中多数断裂的第四纪活动性以“中等”和“弱”为主.但历史地震活动表明,其不同段落上的未来强震活动趋势值得关注,尤其是历史强震活动相对空缺的中南段.展开更多
文摘文中基于D-InSAR技术,利用欧空局C波段升降轨哨兵SAR数据,获取了2021年5月22日青海玛多M_(W)7.3地震的InSAR同震形变场,并对同震形变的空间特征、量级和断层破裂的分段性进行了分析。哨兵卫星的高质量观测数据清晰地描绘了玛多地震的地表破裂迹线,地表破裂长度约210km。为了进一步认识玛多地震断层深部的同震滑动分布特征和发震断层几何性质,基于升、降轨InSAR形变场及精定位余震数据确定的断层几何反演了同震滑动分布,并基于同震库仑应力变化分析了本次地震对周边区域的应力扰动。结果表明,玛多M_(W)7.3地震发生在巴颜喀拉块体内部的一条次级断层上,且与东昆仑断裂带的主断裂近平行,结合野外考察、地质资料和InSAR地表破裂迹线确定的发震断层为昆仑山口-江错断裂。玛多地震产生的同震形变场空间影响范围广,形变场的长轴呈NWW向,升、降轨观测的形变量符号相反,结合哨兵数据的观测几何确定发震断层的运动性质以左旋走滑为主。基于升、降轨InSAR数据得到的最大视线向(Line of Sight,LOS)形变量约为0.9m。同震滑动分布模型显示,整体上断层的走向为276°,倾角为80°,倾向NE,最大滑移量约为6m,平均滑动角为4°,矩震级为M_(W)7.45,地震主体破裂发生在0~10km深度范围内,同震破裂至地表,与野外考察所观测到的广泛分布的同震地表破裂带一致。以玛多-甘德断裂为接收断层的同震库仑应力模型显示,玛多地震在玛多-甘德断裂西段附近产生了明显的应力降,表明玛多地震释放了玛多-甘德断裂的库仑应力,导致后者的地震危险性可能大大降低;而在玛多-甘德断裂和昆仑山口-江错断裂交叉的区域存在应力加载效应,但考虑到玛多地震的余震会释放多余的能量,该区发生较大地震的危险性可能降低。以东昆仑断裂为接收断层的同震库仑应力模型显示,玛多地震在�
基金the U.S. National Science Foundation (Grant Nos. EAR 0738779 and OCE 0727919)the National Basic Research Program of China (Grant No. 2004CB418404)partially by the National Nature Science Foundation of China (Grant No. 40521002)
文摘The Wenchuan earthquake of 12 May 2008 is the most destructive earthquake in China in the past 30 years in terms of property damage and human losses. In order to understand the earthquake process and the geo-morphological factors affecting the seismic hazard, we simulated the strong ground mo-tion caused by the earthquake, incorporating three-dimensional (3D) earth structure, finite-fault rupture, and realistic surface topography. The simulated ground motions reveal that the fault rupture and basin structure control the overall pattern of the peak ground shaking. Large peak ground velocity (PGV) is distributed in two narrow areas: one with the largest PGV values is above the hanging wall of the fault and attributed to the locations of fault asperities and rupture directivity; the other is along the north-western margin of the Sichuan Basin and caused by both the directivity of fault rupture and the ampli-fication in the thick sediment basin. Rough topography above the rupture fault causes wave scattering, resulting in significantly larger peak ground motion on the apex of topographic relief than in the valley. Topography and scattering also reduce the wave energy in the forward direction of fault rupture but increase the PGV in other parts of the basin. These results suggest the need for a localized hazard as-sessment in places of rough topography that takes the topographic effects into account. Finally, had the earthquake started at the northeast end of the fault zone and ruptured to the southwest, Chengdu would have suffered a much stronger shaking than it experienced on 12 May, 2008.
文摘青藏高原东南部边缘的程海-宾川断裂带是一条正断与左旋走滑运动兼具的复合型活动断裂,起着调节青藏高原内部物质向东挤出的重要作用,并控制着区域的主要强震活动.基于GIS(Geographic Information System)技术,利用遥感影像和DEM(Digital Elevation Model)数据提取该区的关键构造地貌信息,对其第四纪分段活动性及特征进行了分析探讨.结果表明,程海-宾川断裂带的第四纪活动具有明显的分段性及空间差异性.其北段的金官-程海盆地主边界断层以正断层活动性质为主,并具有整个断裂带上最高的垂直活动速率;中段的期纳断裂以左旋走滑运动为主,且具有最高的走滑活动速率;南段宾川盆地东缘边界断裂也以正断层活动为主,但垂直活动速率略低于北段.总体上看,程海-宾川断裂带第四纪期间的垂直活动性由北往南降低,水平走滑活动性由中段往南北两端降低.在活动强度方面,程海-宾川断裂带百万年尺度的长期活动速率一直保持着较为稳定的状态,垂直活动速率主要集中在0.09~0.69mm/a,水平走滑速率在0.20~1.40mm/a.整体而言,程海-宾川断裂带中多数断裂的第四纪活动性以“中等”和“弱”为主.但历史地震活动表明,其不同段落上的未来强震活动趋势值得关注,尤其是历史强震活动相对空缺的中南段.
