共查询到18条相似文献，搜索用时 140 毫秒
1.
基于2009—2015年中国大陆GPS水平速度场数据,采用DEFNODE负位错反演程序计算了丽江—小金河断裂带的断层闭锁程度和滑动亏损速率特征,并结合小震精定位结果分析了该断裂带的强震危险性。结果表明,GPS水平观测值与模型值的拟合结果较好,小震分布与闭锁程度结果存在一定的相关性,丽江—小金河断裂的南段—中段南部(丽江—宁蒗)除最南端外基本完全闭锁,断层的滑动亏损速率也相对较大,该段落具有发生较大地震的潜在危险性;而中段中北部—北段闭锁程度要弱得多,尤其在断裂带的北段,闭锁程度很弱,除了南部有部分闭锁,其余地方无强闭锁状态,且在5 km左右深度处断裂基本由闭锁状态转化为蠕滑状态特征,断层的滑动亏损速率也相应很小,该段发生较大地震的可能性较小。 相似文献
2.
为研究龙门山断裂带西南段断层闭锁程度与变形状态,并分析该区域地震危险性,利用1999—2007、2009—2011、2011—2013和2013—2015年共4期GPS速度场,采用DEFNODE负位错反演程序估算了该断裂的闭锁程度和滑动亏损空间动态分布,并结合1990—2017年跨断层水准资料分析了断层的三维运动变形特征。结果表明:(1)龙门山断裂带西南段在汶川地震前后一直处于较强的闭锁状态,且汶川地震使西南段应变积累速度加快,加速了芦山地震的孕育进程;芦山地震后西南段闭锁程度并没有明显减弱,芦山地震对西南段的应变能释放是局部的和有限的。(2)龙门山断裂带4期垂直断层滑动亏损速率均为挤压亏损速率,汶川地震后西南段亏损速率明显增大,而后2期西南段亏损速率逐渐减小,目前依然明显高于汶川地震前量值。(3)汶川地震前跨断层水准结果显示龙门山断裂带西南段处于完全闭锁状态,汶川地震后多个场地的年均垂直变化速率明显增大,并随时间呈逐渐衰减状态,目前已经恢复至汶川地震前正常变化速率,因此西南段仍然处于闭锁状态。综合GPS反演结果和跨断层水准结果分析认为,目前龙门山断裂带西南段在大部分段落处于强闭锁状态下依然有发生大地震的可能性。 相似文献
3.
利用华北地区2009—2014年GPS水平运动速度场数据,采用块体负位错模型反演了郯庐断裂带中南段断层深部滑动速率、断层闭锁程度分布、断层滑动亏损速率分布及地震矩积累率,结合地表应变率分布,对郯庐断裂带中南段深、浅部形变、应变特征以及华北地区的地壳形变模式进行了分析.结果表明:郯庐断裂中南段的北端主要为右旋走滑特性,南端则表现为右旋走滑兼拉张性运动,断层滑动速率在0.9mm·a~(-1)至1.2mm·a~(-1),且沿断层走向由北至南逐次增大.断层闭锁程度分布沿走向分布不均一,断层闭锁深度由最北端的27km增加到中段的32km,至最南端变为5km,断层闭锁最深处与1668年郯城MS8.5震中位置相对应.断层滑动亏损速率沿走向由0.9mm·a~(-1)增加到1.2mm·a~(-1),沿倾向由地表至深部逐渐减小为0mm·a~(-1).地震矩积累率在郯庐断裂带中南段郯城附近较大,而地表对应区域为第二应不变分量的低值区.华北地区地壳变形以块体运动为主,块体内部应变及断层闭锁产生的负位错效应次之;郯庐断裂带中南段断层形变沿走向呈条带状分布,形变宽度单侧小于50km,形变量不超过1mm·a~(-1),且上盘形变略大于下盘. 相似文献
4.
为了综合分析讨论鲜水河断裂带的三维运动与变形动态特征和地震危险性,利用川滇地区1999—2007和2013—2017 2期GPS速度场资料,反演计算了鲜水河断裂带的闭锁程度和平行与垂直断层的滑动亏损速率动态分布;利用布设在鲜水河断裂带附近的1980—2017年跨断层短水准资料,通过计算断层年均变化速率分析了断裂带垂直运动特征。GPS反演结果显示:1999—2007期鲜水河断裂SE段处于强闭锁状态,中段闭锁程度逐渐减弱,到NW段基本为蠕滑状态;2013—2017期鲜水河断裂SE段滑动亏损积累速率明显减弱,只有道孚—八美段之间有一小段闭锁较强,NW段依然大部分为蠕滑状态,只有炉霍SE部一段断层地表至10km深度闭锁稍有增强。水准结果显示:鲜水河断裂NW段侏倭、格篓、虚墟和沟普场地年均垂直变化速率较大,断层垂向活动较为活跃;SE段龙灯坝、老乾宁和折多塘场地年均垂直变化速率很小,断层垂向活动处于闭锁状态;汶川地震后断层垂向活动变化并不明显。综合分析认为鲜水河断裂SE段的地震危险性较高,而汶川地震降低了断层滑动亏损和应力应变能积累速率,可能在一定程度上缓解了鲜水河断裂尤其SE段的地震紧迫性。 相似文献
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利用1999—2007期GPS水平速度场数据,采用Defnode负位错反演程序估算了龙门山断裂在汶川地震前的闭锁程度和滑动亏损分布,结合龙门山断裂带附近地表水平应变率场结果,综合分析了震前地壳变形特征.反演结果表明,震前龙门山断裂中北段处于完全闭锁状态,闭锁深度达到21 km(闭锁比例0.99)左右,垂直断层方向的挤压滑动亏损速率约为2.2 mm/a,平行断层方向的右旋滑动亏损速率约为4.6 mm/a.龙门山断裂南段只有地表以下12 km闭锁程度较高(闭锁比例0.99),垂直断层方向滑动亏损速率约为1.4 mm/a,平行断层方向滑动亏损速率约为4.6 mm/a;在12~16 km处闭锁比例约为0.83,垂直断层方向滑动亏损速率约为1.2 mm/a,平行断层方向滑动亏损速率约为3.8 mm/a;在16~21 km处闭锁比例约为0.75,垂直断层方向滑动亏损速率约为1.1 mm/a,平行断层方向滑动亏损速率约为3.5 mm/a.在21~24 km处整条断裂均逐步转变为蠕滑.上述反演结果与区域应变计算获得的龙门山断裂带中北段整体应变积累速率较低、南段应变积累速率较高相一致,均表明中北段闭锁程度高、南段闭锁程度稍低,该特征可以较好地解释汶川地震时从震中向北东向单向破裂现象. 相似文献
6.
为了研究与总结2008年5月12日汶川8.0级地震前GPS与跨断层资料反映的龙门山断裂带及其周边地区的运动、构造变形、应变积累演化过程,以及汶川地震临震阶段可能的物理机制,本文综合1999~2007期GPS速度场、1999~2008年大尺度GPS基线时间序列、1985~2008年跨断层短水准等资料进行了相关分析与讨论。结果表明:(1)GPS速度剖面结果显示,宽达500km的川西高原在震前有明显的连续变形,而四川盆地一侧和跨龙门山断裂带基本没有变形趋势,表明震前川西高原在持续不断地为已经处于闭锁状态的龙门山断裂带提供能量积累。(2)GPS应变率结果显示,震前龙门山断裂带中北段的NW侧EW向挤压变形明显,变形幅度从远离断裂带较大到靠近断裂带逐渐减小,而断裂带变形微弱;龙门山断裂带西南段周边形成了显著的EW向挤压应变集中区,应变积累速率明显大于中北段。(3)断层闭锁程度反演结果显示,除了汶川地震的震源位置闭锁相对较弱,且西南段有大概20km宽度断层在12~22.5km深度为蠕滑状态以外,震前整条龙门山断裂基本处于强闭锁状态。(4)大尺度GPS基线结果显示,跨南北地震带区域的NE向基线从2005年开始普遍出现压缩转折,反映NE向地壳缩短的相对运动增强。(5)跨断层短水准场地结果显示,震前年均垂直变化速率和形变累积率很低,表明断层近场垂向活动很弱、闭锁较强。通过以上分析认为,在相对小尺度的地壳变形中,震前龙门山断裂带深浅部均处于强闭锁状态,断裂带水平与垂直变形都很微弱,这可能经历了一个缓慢的过程,而且越是临近地震的发生,微弱变形的范围可能越大;在相对大尺度的地壳变形中,震前龙门山断裂带西侧的巴颜喀拉块体东部地区经历了地壳缓慢且持续的缩短挤压变形,为龙门山断裂带应变积累持续提供了动力支持。 相似文献
7.
发生在同一断层部位上0.5～4.0 级的重复地震(也称重复微震)是研究断裂带深部变形的天然(有力)工具.本文系统汇集了川滇地区主要断裂带识别出的 76 组重复地震研究结果,构建了川滇地区重复地震的时空分布图像和断裂带深部变形时空演化特征,结果表明:丽江—宁蒗断裂带在脆韧转换带约23 km深处的滑动速率为4.3～5.4 mm·a－1 ,小江断裂带3.0～12.3 km深处的滑动速率为 1.6～10.1 mm·a－1 ,红河断裂带北段在 6.0～13.4 km深处的滑动速率为2.3～10.0 mm·a－1 ,鲜水河断裂带南段 3.0～18.7 km深处的滑动速率为 3.0～10.2 mm·a－1 ,龙门山断裂带在4.0～17.3 km的汶川 8.0级地震孕育深处的滑动速率为 3.5～9.6 mm·a－1 ,龙门山断裂带南端3.6～18.7 km处滑动速率为 5.8～10.2 mm·a－1 .综合分析认为:川滇地区主要边界断裂带的深部滑动速率较为一致,揭示了川滇地块和巴颜喀拉地块整体协同变形的特征.由重复微震与深部滑动速率变化构建了孕震深处的变形模式,即重复微震与断裂带局部闭锁段在空间位置上存在密切的关联性,强震前孕震闭锁区存在明显的深浅部构造形变差异,震前存在的深部加速变形过程可能是断层亚失稳阶段的具体表征. 相似文献
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《地震地质》2017,(3)
利用青藏高原东北缘及周缘地区1999—2007年和2009—2014年2个时段的GPS水平运动速度场做约束,反演获取了海原-六盘山断裂带的闭锁程度和滑动速率亏损的时空分布演化。结果表明,海原断裂带以左旋走滑亏损为主,六盘山断裂北段以逆冲倾滑速率亏损为主,南段则以正向倾滑为主。其中,毛毛山断裂和老虎断裂西段在2个时段的闭锁深度都达到25km,最大左旋滑动亏损为6mm/a。老虎山东段和海原断裂(狭义)闭锁程度低,主要处于蠕滑状态。六盘山断裂2个时段的闭锁深度可达35km,最大逆冲滑动速率亏损为2mm/a。汶川地震后,六盘山断裂上逆冲滑动速率亏损高值区由中段迁移至北段且范围减小,南段则变成正倾滑速率亏损。毛毛山、老虎山西段和六盘山断裂的地震危险性要明显高于海原-六盘山断裂带其他断层段。 相似文献
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利用1999—2015年GPS水平速度场, 基于块体-位错模型, 反演了青藏高原东北缘4条主要断裂(海原断裂, 六盘山断裂, 陇县—宝鸡断裂, 西秦岭北缘断裂)的闭锁程度和滑动亏损速率的空间分布, 并分析了各断裂的地震危险性。 结果显示, 六盘山断裂南段、 陇县-宝鸡断裂北段、 西秦岭北缘断裂东段闭锁程度最强, 闭锁深度达到24 km左右; 西秦岭北缘断裂东段滑动亏损速率最大, 平均值达到3 mm/a; 六盘山断裂南段、 陇县—宝鸡断裂北段滑动亏损速率平均值达到1.9 mm/a, 稍弱于西秦岭北缘断裂东段; 海原断裂闭锁程度和滑动亏损速率相对较小, 闭锁程度和滑动亏损都仅分布在浅部。 我们认为现阶段海原断裂的地震危险性相对较小, 六盘山断裂南段、 陇县—宝鸡北段、 西秦岭北缘断裂东段地震危险性高于这些断裂的其他段落。 这些结果对于青藏高原东北缘地震危险性判定和地震灾害评估具有参考意义。 相似文献
10.
《地震研究》2016,(3)
基于1999~2007年、2009~2013年两期中国大陆GPS水平速度场数据,使用DEFNODE负位错程序反演计算了汶川地震前后陇西块体周边断层——海原—祁连山断裂、六盘山断裂、庄浪河断裂和西秦岭北缘断裂的断层闭锁程度与滑动亏损动态空间分布,并讨论了汶川地震对块体周边断裂的影响和可能存在的强震危险段。结果表明,汶川地震后西秦岭北缘断裂中西段闭锁程度有所减弱、中东段闭锁程度有所增强,地震可能对其有一定影响;在汶川地震前后,其它断裂的断层闭锁程度没有发生明显改变,地震可能对其影响较弱。目前冷龙岭断裂、金强河断裂、庄浪河断裂、六盘山断裂、西秦岭北缘断裂中西段部分区域的闭锁程度较强,闭锁深度约为20~25 km,结合地质尺度的断层地震空区等结果,分析认为上述断裂可能为地震危险段。汶川地震前后陇西块体周边平行断层滑动亏损速率中,除庄浪河断裂为右旋滑动亏损以外,其它断裂均为左旋滑动亏损;陇西块体周边垂直断层滑动亏损速率则均为挤压。 相似文献
11.
DEFORMATION CHARACTERISTICS AND KINEMATIC PARAMETERS INVERSION OF HAIYUAN FAULT ZONE BASED ON TIME SERIES INSAR 
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下载免费PDF全文 Located at the bend of the northeastern margin of Qinghai-Tibet Plateau, the Haiyuan fault zone is a boundary fault of the stable Alashan block, the stable Ordos block and the active Tibet block, and is the most significant fault zone for the tectonic deformation and strong earthquake activity. In 1920, a M8.5 earthquake occurred in the eastern segment of the fault, causing a surface rupture zone of about 240km. After that, the segment has been in a state of calmness in seismic activity, and no destructive earthquakes of magnitude 6 or above have occurred. Determining the current activity of the Haiyuan fault zone is very important and necessary for the analysis and assessment of its future seismic hazard.
To study activity of the Haiyuan fault zone, the degree of fault coupling and the future seismic hazard, domestic and foreign scholars have carried out a lot of research using geology methods and GPS geodetic techniques, but these methods have certain limitations. The geology method is a traditional classical method of fault activity research, but dislocation measurement can only be performed on a local good fault outcrop. There are a limited number of field measurement points and the observation results are not equally limited depending on the sampling location and sampling method. The distribution of GPS stations is sparse, especially in the near-fault area, there is almost no GPS data. Therefore, the spatial resolution of the deformation field features obtained by GPS is low, and there are certain limitations in the kinematic parameter inversion using this method.
In this study, we obtain the average InSAR line-of-sight deformation field from the Maomaoshan section to the mid-1920s earthquake rupture segment of the Haiyuan earthquake in the period from 2003 to 2010 based on the PSInSAR technique. The results show that there are obvious differences between the slip rates of the two walls of the fault in the north and the south, which are consistent with the motion characteristics of left-lateral strike-slip in the Haiyuan fault zone. Through the analysis of the high-density cross-fault deformation rate profile of the Laohushan segment, it is determined that the creep length is about 19km. Based on the two-dimensional arctangent model, the fault depth and deep slip rate of different locations in the Haiyuan fault zone are obtained. The results show that the slip rate and the locking depth of the LHS segment change significantly from west to east, and the slip rate decreases from west to east, decreasing from 7.6mm/a in the west to 4.5mm/a in the easternmost. The western part of the LHS segment and the middle part are in a locked state. The western part has a locking depth of 4.2~4.4km, and the middle part has a deeper locking depth of 6.9km, while the eastern part is less than 1km, that is, the shallow surface is creeping, and the creep rate is 4.5~4.8mm/a. On the whole, the 1920 earthquake's rupture segment of the Haiyuan fault zone is in a locked state, and both the slip rate and the locking depth are gradually increased from west to east. The slip rate is increased from 3.2mm/a in the western segment to 5.4mm/a in the eastern segment, and the locking depth is increased from 4.8km in the western segment to 7.5km in the eastern segment. The results of this study refine the understanding of the slip rate and the locking depth of the different segments of the Haiyuan fault zone, and provide reference information for the investigation of the strain accumulation state and regional seismic hazard assessment of different sections of the fault zone. 相似文献
12.
利用1999-2007和2009-2011年中国大陆GPS水平速度场数据, 采用DEFNODE(反演计算弹性岩石圈块体旋转、 应变和块体边界断层闭锁或同震滑动的Fortran程序)负位错反演程序估算了芦山地震前龙门山断裂带的三维闭锁程度, 并结合剖面结果分析了断层深浅部变形特征. GPS反演结果表明, 1999-2007年, 龙门山断裂中北段(闭锁比例为0.99)处于强闭锁(本文将闭锁比例大于0.97的称为强闭锁)状态; 龙门山断裂南段地表以下深度16 km内为强闭锁, 深度16-21 km处闭锁比例降低为0.62, 深度21-24 km处整条断裂逐渐转变为蠕滑状态. 2009-2011年, 即汶川地震后, 龙门山断裂中北段处于震后蠕滑状态; 龙门山断裂南段深度16-21 km处闭锁比例降低为0.45, 其它位置闭锁程度保持不变. GPS剖面结果显示, 2009-2011年, 即汶川地震后, 龙门山断裂中北段为逆冲兼右旋走滑运动; 而南段断层不能自由滑动、 变形宽度较大. 综合分析认为, 汶川地震时, 龙门山断裂南段并没有发生破裂, 一直处于较强的闭锁状态, 汶川地震的发生又加速了芦山地震的孕育进程; 由于龙门山断裂带南段的闭锁深度较中北段浅, 因此芦山地震较汶川地震强度低、 震级小、 破裂范围窄. 相似文献
13.
利用1999—2007期和2009—2013期中国大陆GPS速度场数据,采用DEFNODE负位错反演程序估算了川滇菱形块体东边界——鲜水河—安宁河—则木河—小江断裂带在汶川地震前后的断层闭锁程度和滑动亏损空间分布动态变化特征,讨论了汶川地震对该断裂系统的影响范围和程度,并结合b值空间分布和地震破裂时-空结果分析了断裂系统的强震危险段.结果表明,汶川地震前鲜水河断裂最南端为完全闭锁(闭锁深度25km),中南段地表以下10~15km深度为强闭锁状态,中北段基本处于蠕滑状态;安宁河断裂最南端闭锁很弱,其余位置闭锁深度为10~15km;则木河断裂除最南端闭锁较弱以外,其余位置基本为完全闭锁;小江断裂在巧家以南、东川以南、宜良附近、华宁以北等四处位置闭锁较弱,其余位置为强闭锁.10年尺度的GPS速度场反演所得断层闭锁程度所指示的强震危险段,主要为鲜水河断裂道孚—八美段、安宁河断裂中段、则木河断裂中北段、小江断裂北段东川附近、小江断裂南段华宁—建水段,该结果与地质尺度的断层地震空区和30年尺度的b值空间分布所指示的危险段落具有一致性.汶川地震后断裂带远、近场速度分布和块体运动状态发生变化,这种区域地壳运动调整使得负位错模型反演得到的断裂带闭锁情况发生一定变化.汶川地震前后川滇菱形块体东边界平行断层滑动亏损速率均为左旋走滑亏损,且在安宁河断裂北端、则木河断裂中北段滑动亏损速率最大;除鲜水河断裂中南段与最南端和小江断裂东川附近以外,其余断裂震后滑动亏损速率均有所增加.垂直断层滑动亏损速率既有拉张亏损也有挤压亏损,且鲜水河断裂最南端由震前挤压转变为震后拉张,其余断裂除了安宁河断裂和小江断裂中段与最北端存在挤压滑动亏损速率外均为拉张速率. 相似文献
14.
Based on GPS velocity during 1999-2007, GPS baseline time series on large scale during 1999-2008 and cross-fault leveling data during 1985-2008, the paper makes some analysis and discussion to study and summarize the movement, tectonic deformation and strain accumulation evolution characteristics of the Longmenshan fault and the surrounding area before the MS8.0 Wenchuan earthquake, as well as the possible physical mechanism late in the seismic cycle of the Wenchuan earthquake. Multiple results indicate that:GPS velocity profiles show that obvious continuous deformation across the eastern Qinghai-Tibetan Plateau before the earthquake was distributed across a zone at least 500km wide, while there was little deformation in Sichuan Basin and Longmenshan fault zone, which means that the eastern Qinghai-Tibetan Plateau provides energy accumulation for locked Longmenshan fault zone continuously. GPS strain rates show that the east-west compression deformation was larger in the northwest of the mid-northern segment of the Longmenshan fault zone, and deformation amplitude decreased gradually from far field to near fault zone, and there was little deformation in fault zone. The east-west compression deformation was significant surrounding the southwestern segment of the Longmenshan fault zone, and strain accumulation rate was larger than that of mid-northern segment. Fault locking indicates nearly whole Longmenshan fault was locked before the earthquake except the source of the earthquake which was weakly locked, and a 20km width patch in southwestern segment between 12km to 22.5km depth was in creeping state. GPS baseline time series in northeast direction on large scale became compressive generally from 2005 in the North-South Seismic Belt, which reflects that relative compression deformation enhances. The cross-fault leveling data show that annual vertical change rate and deformation trend accumulation rate in the Longmenshan fault zone were little, which indicates that vertical activity near the fault was very weak and the fault was tightly locked. According to analyses of GPS and cross-fault leveling data before the Wenchuan earthquake, we consider that the Longmenshan fault is tightly locked from the surface to the deep, and the horizontal and vertical deformation are weak surrounding the fault in relatively small-scale crustal deformation. The process of weak deformation may be slow, and weak deformation area may be larger when large earthquake is coming. Continuous and slow compression deformation across eastern Qinghai-Tibetan Plateau before the earthquake provides dynamic support for strain accumulation in the Longmenshan fault zone in relative large-scale crustal deformation. 相似文献
15.
16.
鄂拉山断裂是位于青藏高原东北缘的一条右旋走滑断裂,前人通过野外地质考察厘定了其万年尺度的长期滑动速率,但对其现今运动学特征的认识仍不足.本文利用近二十年获取的GPS速度场,以贝叶斯理论作为断层滑动反演的理论框架,采用MCMC(马尔科夫链蒙特卡罗)方法,构建鄂拉山断裂的运动学模型,探讨该断裂的现今震间滑动速率和闭锁状态.研究结果表明,鄂拉山断裂的闭锁深度约为15 km,深部的滑动速率为5.0±1.5 mm·a^-1,反映了断层两侧地壳的整体相对运动速率.尽管当前研究区的GPS观测台站分布相对稀疏,但仍可以探测出断层闭锁状态沿走向的变化.在断层中段,由于几何形态的变化,形成了强闭锁的凹凸体,闭锁系数达到0.6~0.7;断层的南段和北段有明显的蠕滑特征,计算得到的闭锁系数仅为0.2~0.3.进一步计算凹凸体上由于滑动亏损产生的等效地震矩积累率为2.35×10^17 N·m/a,等同于M W5.6地震的能量水平.最后,针对研究区域GPS台站分布稀疏的局限,本研究基于滑动模型的误差最小化准则,给出有限资源条件下的GPS台站优化增设方案. 相似文献
17.
安宁河—则木河断裂带及东侧的大凉山断裂带作为大凉山次级块体西侧与东侧边界,具有发生大地震的活动构造背景.本文意在用有限的形变数据和地震数据两种资料评估大凉山次级块体边界断裂带的孕震深度及其地震危险性.采用弹性半空间模型对安宁河断裂、则木河断裂和大凉山断裂带滑动速率和闭锁深度进行了详细分析;计算了90%、95%和99%不同分位数的小震深度下界值并与GPS得到的闭锁深度进行对比,分析二者异同点.结果显示,安宁河断裂北段闭锁深度为6.2 km,不到90%分位小震震源深度16 km的一半,表明该段在1952年MS63/4地震后,断层逐渐趋于闭锁;而在6~16 km深度主要以小地震和无震滑动两种形式释放能量,存在深部蠕滑运动.大凉山断裂北段在0~10 km范围内完全闭锁,而10~25 km闭锁程度较弱.安宁河断裂南段、则木河断裂、大凉山断裂中段和南段均处于完全闭锁阶段,闭锁深度接近90%分位数小震深度的下界值,标准差约为0.94 km.此外,A、B、C三个剖面的反演结果表明大凉山次级块体的运动自北向南具有顺时针旋转特性,与川滇块体顺时针运动特征吻合.大凉山次级块体北、中、南三段边界断裂及块体内部总的滑动速率分别为9.8 mm·a-1、8.9 mm·a-1和8.4 mm·a-1,呈自北向南递减趋势.大凉山断裂南段布拖断裂和交际河断裂积累的能量分别能够发生一次矩震级为MW7.5的地震,离逝时间已经接近地震平均复发间隔,未来100年大地震的发震概率分别为7.1%和5.9%,应对其地震危险性给予重视. 相似文献
18.
In order to analyze 3-dimensional movement and deformation characteristics and seismic risk of the Xianshuihe fault zone, we inverted for dynamic fault locking and slip deficit rate of the fault using the GPS horizontal velocity field of 1999-2007 and 2013-2017 in Sichuan-Yunnan region, and calculated annual vertical change rate to analyze the vertical deformation characteristics of the fault using the cross-fault leveling data during 1980-2017 locating on the Xianshuihe fault. The GPS inversion results indicate that in 1999-2007, the southeastern segment of the fault is tightly locked, the middle segment is less locked, and the northwestern segment is basically in creeping state. In 2013-2017, the southeastern segment of the fault is obviously weekly locked, in which only a patch between Daofu-Bamei is locked, and the northwestern segment is still mostly in creeping state, in which only a patch at southeastern Luhuo is slightly locked from surface to 10km depth. The cross-fault leveling data show that annual vertical change rate of the Zhuwo, Gelou, Xuxu and Goupu sites on the northwestern segment is larger, which means vertical movement is relatively active, and annual vertical change rate of the Longdengba, Laoqianning, and Zheduotang sites on the southeastern segment is small, which means the fault is locked, and the vertical movement changes little before and after the Wenchuan earthquake. Combining with the 3-dimensional movement and deformation, seismic activity and Coulomb stress on the Xianshuihe Fault, we consider the seismic risk of the southeastern segment is larger, and the Wenchuan earthquake reduced the far-field sinistral movement and the fault slip deficit rate, which may reduce the stress and strain accumulation rate and relieve the seismic risk of the southeastern segment. 相似文献