共查询到20条相似文献，搜索用时 625 毫秒
1.
本文利用在龙门山断裂带周边布设的57个台站自2008年11月至2009年11月为期一年的垂直分量连续地震环境噪声数据,通过短周期地震环境噪声成像方法,获得了龙门山断裂带中北段地壳25km深度范围的S波精细速度结构.结果表明:(1)龙门山断裂带周边区域10km以上的速度结构与地表断裂的分布形态具有良好的一致性,速度结构控制了龙门山主要断层的深部延展特征;在15km及以下深度,S波速度结构呈现沿龙门山和沿岷山隆起走向的交叉构造格局,由此造成的速度结构差异可能影响了汶川地震的破裂过程;(2)速度结构随深度的分布特征为龙门山断裂带主要断层的深部延伸形态给出了良好的约束,结果进一步确认了龙门山断裂中段的高角度铲型断裂构造特征;(3)研究区的南端发现了龙门山断裂下方20km以下深度具有与松潘地块中地壳低速层相关的低速结构的迹象,这可能是汶川地震破裂带南段22km左右深度存在脆韧转换带的一个证据.研究结果显示出密集台阵和短周期环境噪声成像方法在地壳浅部精细结构和断层探测研究中具有巨大潜力. 相似文献
2.
Hongfeng Yang 《地震科学（英文版）》2015,28(2):151-162
Crustal faults usually have a fault core and surrounding regions of brittle damage, forming a low-velocity zone(LVZ) in the immediate vicinity of the main slip interface. The LVZ may amplify ground motion, influence rupture propagation, and hold important information of earthquake physics. A number of geophysical and geodetic methods have been developed to derive high-resolution structure of the LVZ. Here, I review a few recent approaches, including ambient noise cross-correlation on dense across-fault arrays and GPS recordings of fault-zone trapped waves. Despite the past efforts, many questions concerning the LVZ structure remain unclear, such as the depth extent of the LVZ. High-quality data from larger and denser arrays and new seismic imaging technique using larger portion of recorded waveforms, which are currently under active development, may be able to better resolve the LVZ structure. In addition, effects of the alongstrike segmentation and gradational velocity changes across the boundaries between the LVZ and the host rock on rupture propagation should be investigated by conducting comprehensive numerical experiments. Furthermore, high-quality active sources such as recently developed large-volume airgun arrays provide a powerful tool to continuously monitor temporal changes of fault-zone properties, and thus can advance our understanding of fault zone evolution. 相似文献
3.
The geometry of faults at seismogenic depths and their continuation into the ductile zone is of interest for a number of applications ranging from earthquake hazard to modes of lithospheric deformation. Teleseismic passive source imaging of faults and shear zones can be useful particularly where faults are not outlined by local seismicity. Passive seismic signatures of faults may arise from abrupt changes in lithology or foliation orientation in the upper crust, and from mylonitic shear zones at greater depths. Faults and shear zones with less than near-vertical dip lend themselves to detection with teleseismic mode-converted waves (receiver functions) provided that they have either a contrast in isotropic shear velocity (V s), or a contrast in orientation or strength of anisotropic compressional velocity (V p). We introduce a detection method for faults and shear zones based on receiver functions. We use synthetic seismograms to demonstrate common features of dipping isotropic interfaces and contrasts in dipping foliation that allows determination of their strike and depth without making further assumptions about the model. We proceed with two applications. We first image a Laramide thrust fault in the western U.S. (the Wind River thrust fault) as a steeply dipping isotropic velocity contrast in the middle crust near the surface trace of the fault; further downdip and across the range, where basin geometry suggests the fault may sole into a subhorizontal shear zone, we identify a candidate shear zone signal from midcrustal depths. The second application is the use of microstructural data from exhumed ductile shear zones in Scotland and in the western Canadian Shield to predict the character of seismic signatures of present-day deep crustal shear zones. Realistic anisotropy in observed shear fabrics generates a signal in receiver functions that is comparable in amplitude to first-order features like the Moho. Observables that can be robustly constrained without significant tradeoffs are foliation strike and the depth of the foliation contrast. We find that an anisotropy of only a few percent in the shear zone is sufficient to generate a strong signal, but that the shear zone width is required to be >2 km for typical frequencies used in receiver function analysis to avoid destructive interference due to the signals from the boundaries of the shear zone. 相似文献
4.
结合汶川地震断裂带动态监测,利用快速响应探测系统,开展了断层带浅部结构人工地震探测.针对地震断裂带动态监测条件下的复杂波场和低信噪比的情况,在f-k波场分离的基础上,分别利用了折射波共中心点成像、面波速度反演、反射波叠加成像方法,进行了浅层断层和构造成像处理,并对处理结果进行了综合解释,给出了断裂带浅部断层分布和速度特征.为汶川地震龙门山断裂带东北端动态监测提供了基础结构信息,所发展的断裂带快速响应探测技术对于地震应急动态监测具有重要意义. 相似文献
5.
合肥市位于合肥盆地东南缘,东侧紧邻郯庐断裂带,多条大型隐伏断裂穿过市区.为进一步认识合肥城市下方隐伏断裂的空间展布、性质,以及城市复杂的沉积环境,本文利用布设在合肥市区的58套三分量短周期地震仪组成的台阵,获得了37天的三分量连续波形数据,通过基于射线追踪的面波走时直接成像方法反演得到了合肥市地壳浅部0.6~3.6 km的三维剪切波速度结构,速度结构图像展现了地壳浅部的横向不均匀性和纵向成层性,揭示出NNE、NWW和近EW三组不同走向的隐伏断裂在城市地下浅部的构造特征.取得以下认识：（1）合肥市南、北方向在浅地表（2 km以内）存在显著速度差异,速度分界线位置与已知的近EW向的蜀山断裂一致,断裂南侧呈现低速凹陷,北侧则为高速隆起.低速中心深度达2~3 km,速度异常与该断裂在合肥盆地东部演化过程中的构造反转沉积了不同地层有关;（2）合肥市区存在明显的高速异常带,其走向、位置与穿过该区域的郯庐断裂带西支主干断裂相符,其中五河—合肥断裂在市区北部以东呈现低速凹陷特征,低速区范围与肥东凹陷晚白垩纪以来的沉积构造边界一致,认为肥东凹陷的最大沉积厚度可达2 km以上;（3）合肥市中心跨郯庐断裂带西支主干断裂之间呈现明显的凹、隆相间的复杂构造,推测其是在多组断裂的共同拉伸作用下形成的小型沉积盆地,沉积中心位于郯庐断裂带内部,最大厚度可达3~4 km.由于其展布方向在不同深度与该区域断裂的走向具有明显的相关性,推测不同深度的沉积形态与郯庐断裂带在不同时期的构造演化过程有关. 相似文献
6.
利用横跨地表破裂带的小点距的地震测线, 对2001年11月14日昆仑山口西8.1级地震进行了断层围陷波的观测实验. 经过数字滤波和频谱分析等技术, 由地震记录图中分离出了断层围陷波. 资料处理结果表明: ① 无论是人工地震震源还是天然地震震源, 只要位于断层带内或紧靠断层带, 均能激发断层围陷波; ② 断层围陷波的能量主要集中于断层带内, 其振幅随测点与断层带距离的增加而急剧衰减; ③ 断层围陷波的优势频率与断层的宽度及断层带内介质的速度有关, 断层带越宽, 或断层带内部介质速度越低, 则观测到的断层围陷波的优势频率越低; ④ 断层围陷波存在着频散现象; ⑤ 根据昆仑山口西地震测线断层围陷波的观测结果, 可推断该处破裂面宽度为300 m左右, 远远大于地表破裂带的宽度. 相似文献
7.
Study on rupture zone of the M=8.1 Kunlun Mountain earthquake using fault-zone trapped waves 总被引：1，自引：0，他引：1
Introduction The study on deep crustal faults has been one of the most vigorous subjects in seismology. In the past, 3-D deep seismic sounding and 3-D seismic tomography were usually used for this pur-pose. But it is difficult to obtain the fine structures of the faults in deep crust by these methods. Recently, seismologists in the world pay more attention to the fault zone trapped waves. Since the fault-zone trapped waves arise from coherent multiple reflections at two boundaries of the fau… 相似文献
8.
The observation of the fault-zone trapped waves was conducted using a seismic line with dense receivers across surface rupture zone of the M=8.1 Kunlun Mountain earthquake. The fault zone trapped waves were separated from seismograms by numerical filtering and spectral analyzing. The results show that: a) Both explosion and earthquake sources can excite fault-zone trapped waves, as long as they locate in or near the fault zone; b) Most energy of the fault-zone trapped waves concentrates in the fault zone and the amplitudes strongly decay with the distance from observation point to the fault zone; c) Dominant frequencies of the fault-zone trapped waves are related to the width of the fault zone and the velocity of the media in it. The wider the fault zone or the lower the velocity is, the lower the dominant frequencies are; d) For fault zone trapped waves, there exist dispersions; e) Based on the fault zone trapped waves observed in Kunlun Mountain Pass region, the width of the rupture plane is deduced to be about 300 m and is greater than that on the surface. 相似文献
9.
峨眉山大火成岩省是我国境内最早获得国际学术界广泛认可的大火成岩省,对于认识地幔柱形成与作用机理、生物与环境演化、资源富集与成矿机制等具有重要意义.本文利用峨眉山大火成岩省宽频带地震台阵(COMPASS-ELIP)以及云南、四川区域地震台网的部分台站资料,基于分格加权叠加策略实现接收函数和面波频散在信息来源和分辨尺度方面的协同;进而开展联合反演,重建了峨眉山大火成岩省关键剖面下方的地壳横波速度结构.研究结果显示:研究区地壳平均S波速度,沿剖面呈现自西向东先增大后减小的分带性,内带中、下地壳速度较高,尤其是下地壳存在明显的高速异常(V_s约3.8~4.2 km·s~(-1))丽江—小金河断裂带和水城—紫云断裂带的东西两侧,中上地壳存在低速层(V_s约3.3 km·s~(-1)),尤其是水城—紫云断裂带东西两侧的中地壳低速层尤为明显.结合本文以及现有的系列研究结果,进一步确认内带中、下地壳高速对应二叠纪古地幔柱作用的遗迹,大规模岩浆的底侵和内侵,不仅改造了滇中块体的地壳结构和组分,而且也改变了地壳的流变强度,进而对现今青藏高原东南缘的深部过程产生了深远影响. 相似文献
10.
High resolution tomography of the Tanlu fault zone near Hefei with passive seismic and magnetotelluric linear array data 
下载免费PDF全文
下载免费PDF全文 Jian Xu Kangdong Wang Junlun Li Ning Gu Ning Ding Jiawei Qian Wen Yang Haijiang Zhang 《地震科学（英文版）》2021,34(1):24-35
As the largest fault trending NNE-SSW to NE-SW in the eastern Eurasia Continent,the Tanlu fault zone(TLFZ)extends over 2,400 km within China,roughly from Wuxue,Hubei Province,to Russia.Since the Quaternary period,the TLFZ has been an earthquake-prone area in eastern China where several major earthquakes resulted by tectonic compression occurred,causing tremendous casualties and significant economic losses.Many studies on different segments of the TLFZ have been carried out in the past few decades.However,numerous key questions regarding the fault zone remain unanswered due to a lack of clear subsurface characterization and fault delineation.In this study,we present high-resolution tomographic results across the TLFZ to the east of Hefei,where one 22-km-long passive seismic array with densely spaced short-period nodes,and a 24-km-long magnetotelluric array were deployed adjacent to each other.We find the velocity and resistivity variations are highly consistent with known surface geology.Sharp property contrasts in both the seismic shear wave velocity and electrical resistivity profiles clearly delineate the Tanlu F1 fault(TLF-1)near Hefei.More interestingly,an upwelling with distinct high velocity is imaged within the Hefei Basin to the west of the TLF-1,whereas a slanted block with low-velocity and low-resistivity seems to cut into or thrust upon the high-grade to low-grade middle-pressure rocks in the Zhangbaling uplift right below the Tanlu F2 ductile shear fault(TLF-2).The presented results show a new approach to characterize deep subsurface structure of the TLFZ beyond 2-km depths using passive data,which it is often difficult for active seismic surveys with refracted and reflected waves to image. 相似文献
11.
汤西断裂的断层围陷波初步研究 总被引：6，自引：0，他引：6
作为断层围陷波方法在城市活断层探测中的首次尝试,我们针对太行山山前断裂带南段的汤西断裂开展了爆炸震源的观测试验。运用数字滤波和频谱分析等技术,由地震记录图分离出了断层围陷波。根据2横测线的观测结果,可确定断层的位置,并可推测断层在该处宽度为200～300m。破裂面较宽,可能与其张性特征有关。分频道地震图显示,断层围陷波具有正频散现象,其低频分量传播较快。这表明断层围陷波是一种面波,可利用其频散规律研究断裂带内介质的物理性质。这次的观测结果也表明,断层围陷波并不局限于新破裂带,在老断层中也能形成和传播。事实上,只要断层带内外的介质在物理性质上有较大的差异,均能产生沿断层传播的围陷波。在城市活断层探测中,断层围陷波的方法具有非常独特的优越性 相似文献
12.
在城市活断层勘探中,对于面波干扰大、地震反射波法难以开展工作的区域,可尝试利用地震折射波法进行探测,并对折射波法探测的原始记录采用时间项、差异时距曲线和有限差分成像等方法进行综合计算、分析,以探索折射波法在城市活断层勘探中的应用成效。文中针对郑州市须水断层西段浅层地震折射波法勘探记录,利用时间项、差异时距曲线和有限差分成像等计算方法,获取剖面速度结构与界面构造;综合震相特征、计算结果等资料确定主要地层的界面深度和构造特征,3种方法都取得了相近的结论。后又通过在测线上4个钻孔资料的验证,认为3种方法的计算结果与钻孔资料相吻合,说明折射波法勘探在城市活断层探测中的应用是可行的 相似文献
13.
Dabie Orogen has a series of special tectonic and geological features which make it important to the study of the tectonic evolution of mainland China and East Asia. The distribution of high pressure/ultra-high pressure metamorphic rocks discovered on the surface, the specific location of a series of deep and shallow sutures in the collisional convergence collage, and the seismogenic environment of shallow earthquakes attract many scientists continuously to study the interesting Dabie Orogen.
In this paper, we used waveform records of 200 broadband seismic stations deployed by China Digital Seismograph Network and vertical component records of 21 mobile seismic stations located in the Dabie-Tanlu orogenic zone and its surrounding areas. Based on seismic ambient noise tomography, we have obtained the phase velocity distributions of Rayleigh surface wave with the periods between 8~40s, with the resolution higher than 50km. The high velocity anomalies are observed on the Hong'an-Tongbo region in the images of 8~16s phase velocity, which decreases with increasing periods. These high velocity anomalies are in consistence with the ultra-high pressure(UHP)metamorphic rocks of the region. It leads us an estimation of the extension of UHP metamorphic rocks at various depths. The distribution of these anomalies found in phase velocity maps of 8s to 16s indicates that the estimated depth is up to~20km. The horizontal distribution forms a heart shape, which is narrower on western side and wider on the eastern side. It is very much consistent with the surface observations. The whole shape is similar to a cone that laterally extends its wings on the southwest. It indicates that the high-pressure/ultra-high pressure metamorphic rocks had experienced quick exhumation after they broke and formed a drag at the tail, and the residual area formed by the fast exhumation was likely to be invaded by magma. We agree that it has experienced complex structural history, such as stretching, magmatic emplacement and tectonic extrusion, resulting in the high-pressure/UHP metamorphic rocks finally exhuming on the surface with the structural pattern of narrower on the western margin and wider on the eastern margin in the Hong'an-Tongbo area.
The significant phase velocity difference from the period of 8s to 35s on both sides of the southern Tanlu fault zone enables us to infer that the Tanlu fault zone is a deep and huge fault, and the entire crust of the eastern zone of Dabie was cut by the Tanlu fault zone. It demonstrates that the Dabie block is separated from the northern Subei Basin and southern Yangtze blocks, which forms a seismogenic environment suitable for the generation of small-to-intermediate earthquakes in this region. Most of earthquakes in Anhui and adjacent provinces are distributed in those areas where the phase velocities changed dramatically, which are in consistence with the small faults of the upper crust in shallow layers of the Dabie-Tanlu orogenic belt. The shallow-source earthquakes mainly occur in velocity contrast regions, as demonstrated by the short period images. Earthquakes distribution and velocity maps show that the possible distribution of tiny faults of the upper crust can be roughly inferred from the geological structure. It helps to understand the seismogenic environment and seismic hazard in the Dabie areas. We conclude that the shallower faults with different velocity on either side of this region are still seismically active. These results have important significance for understanding the tectonic activity of the research areas.More detail work and further discussion are needed on the velocity structure of the Dabie orogen. 相似文献
14.
The observation of the fault-zone trapped waves was conducted using a seismic line with dense receivers across surface rupture
zone of the M=8.1 Kunlun Mountain earthquake. The fault zone trapped waves were separated from seismograms by numerical filtering and spectral
analyzing. The results show that: a) Both explosion and earthquake sources can excite fault-zone trapped waves, as long as
they locate in or near the fault zone; b) Most energy of the fault-zone trapped waves concentrates in the fault zone and the
amplitudes strongly decay with the distance from observation point to the fault zone; c) Dominant frequencies of the fault-zone
trapped waves are related to the width of the fault zone and the velocity of the media in it. The wider the fault zone or
the lower the velocity is, the lower the dominant frequencies are; d) For fault zone trapped waves, there exist dispersions;
e) Based on the fault zone trapped waves observed in Kunlun Mountain Pass region, the width of the rupture plane is deduced
to be about 300 m and is greater than that on the surface.
Foundation item: Joint Earthquake Science Foundation of China (201001).
Contribution No. RCEG200305, Research Center of Exploration Geophysics, China Earthquake Administration. 相似文献
15.
低速断层破碎带内传播的断层围陷波是断层内部信息的重要载体,研究其波场特征是反,演断层内部结构的关键。前人对围陷波的模拟主要针对垂直断层,但实际断层大部分是倾斜的。本文利用谱元法数值模拟地震波在垂直和倾斜断层区域的传播,并分别单独改变断层破碎带或断层两盘速度差异等参数,对比分析地震动在时域和频域发生的变化,研究这些参数对波场特征的影响。对比研究表明,当存在一定宽度的低速破碎带时,倾斜断层对近断层区域波场的影响和垂直断层相比在幅值分布上有比较显著的差异,尤其是当断层两盘同时还存在速度差异时;在倾斜和垂直断层破碎带上方,均能产生断层围陷波,其幅值特征差异不大,但在跨断层平面上的质点极化方式可能会存在差异:垂直断层围陷波质点极化方向表现为单一,而倾斜断层可能会出现多个方向。这些模拟结果有助于反演真实断层破碎带结构,也能够加深对近断层的强地面运动特征的认识。 相似文献
16.
秦岭—大别造山带西起青藏高原东北缘,东至郯庐断裂带,是华北板块和扬子板块之间的碰撞造山带.本文收集陕、豫、皖、赣、湘、鄂、渝等区域地震台网的160个宽频带地震台站连续两年地震背景噪声数据,用双台站互相关算法获得瑞利面波经验格林函数,提取相速度频散曲线,并根据面波层析成像反演得到秦岭—大别及邻区周期8~35 s范围内相速度分布图像.结果显示,大别地块在14 s相速度分布图中呈现低速异常,与8 s相速度分布图中的高速异常形成鲜明对比,反映大别HP/UHP(high pressure/ultrahigh pressure metamorphic rocks,高压/超高压变质岩)的影响仅存在于上地壳.25 s相速度图中,大致以太行一武陵重力梯度带为界,东部以高速异常为主,西部以低速异常为主,反映了地壳东薄西厚的结构特征.14~35 s相速度分布图显示郯庐断裂带南段东西两侧的显著差异,佐证了郯庐断裂带发生大规模左行平移运动时,其南段可能切入壳幔边界.同时,郯庐断裂带南段可能存在一个热物质上涌的通道,熔融的热物质通过该通道上升,混入大别地区的中下地壳,造成了红安一大别造山带的差异隆升.南秦岭与四川盆地东北部表现为低速异常,是否与青藏高原物质东流或者南秦岭的拆沉有关,还有待于进一步深入研究. 相似文献
17.
郯庐断裂带是中国东部最大的一个活动构造带,其内部结构非常复杂,不同区段表现出不同特征的构造样式.本文采用浅层地震反射波成像技术对郯庐断裂带宿迁段的近地表结构进行了高分辨率成像,利用该区已有的深地震反射剖面数据,采用初至波层析成像方法获得了郯庐断裂带的浅层P波速度结构.结果表明,郯庐断裂带宿迁段是一个由多条断裂以及凹陷和隆起构成的复杂构造带,且新生代地层厚度和地震波速分布明显受到断裂的影响与控制.郯庐断裂带的东、西两侧为基底隆起区,近地表速度结构呈现为明显的高速特征,新生代地层厚度小于200m.郯庐断裂带总体显示为低速凹陷结构,新生代地层厚度在300～600m之间变化,最厚处位于宿迁市的陵城镇附近.郯庐断裂带宿迁段主要由5条断裂构成,从这些断裂的上断点埋深和第四纪活动特征来看,郯庐断裂带的东边界断裂F_1和西边界断裂F_4的活动性相对较弱,为第四纪早期活动断裂.断裂F_2和F_3控制了郯庐断裂带内部的新生代凹陷,两者的活动时代分别为中更新世和晚更新世.安丘—莒县断裂F_5位于断裂F_1和F_2之间,由2条相向而倾的分支断层F_5和F_(5-1)构成,其活动时代分别为全新世和晚更新世.研究结果为进一步认识郯庐断裂带宿迁段的近地表特征及其活动性提供了新证据. 相似文献
18.
基于不同类型活断层产生的地震地表破裂带宽度和跨断层探槽地质剖面的地层强变形带宽度等观测事实 ,结合地面建筑设施毁坏带与活断层密切的空间位置关系 ,采用统计分析方法 ,确定了活断层“避让带”宽度为 30m。各活断层更为准确的避让带宽度可通过分析跨断层探槽地质剖面上地层的变形特征加以验证或修订 ;活断层斜列阶区、平行次级断层围限区、走向弯曲区等特殊地域的避让带宽度为这些地域宽度与两外侧各 15m之和。建议有关部门进行活断层“避让带”立法与执法管理 ,并加强活断层鉴定及其地表活动线几何结构形态的准确定位工作 ,积极而有效地减轻地震灾害 相似文献
19.
Crustal structure beneath Liaoning province and the Bohai Sea and its adjacent region in China based on ambient noise tomography 下载免费PDF全文
下载免费PDF全文 The velocity structure of the crust beneath Liaoning province and the Bohai sea in China was imaged using ambient seismic noise recorded by 73 regional broadband stations. All available three-component time series from the 12-month span between January and December 2013 were cross-correlated to yield empirical Green's functions for Rayleigh and Love waves. Phasevelocity dispersion curves for the Rayleigh waves and the Love waves were measured by applying the frequencytime analysis method. Dispersion measurements of the Rayleigh wave and the Love wave were then utilized to construct 2D phase-velocity maps for the Rayleigh wave at8–35 s periods and the Love wave at 9–32 s periods,respectively. Both Rayleigh and Love phase-velocity maps show significant lateral variations that are correlated well with known geological features and tectonics units in the study region. Next, phase dispersion curves of the Rayleigh wave and the Love wave extracted from each cell of the 2D Rayleigh wave and Love wave phase-velocity maps,respectively, were inverted simultaneously to determine the3 D shear wave velocity structures. The horizontal shear wave velocity images clearly and intuitively exhibit that the earthquake swarms in the Haicheng region and theTangshan region are mainly clustered in the transition zone between the low-and high-velocity zones in the upper crust, coinciding with fault zones, and their distribution is very closely associated with these faults. The vertical shear wave velocity image reveals that the lower crust downward to the uppermost mantle is featured by distinctly high velocities, with even a high-velocity thinner layer existing at the bottom of the lower crust near Moho in central and northern the Bohai sea along the Tanlu fault, and these phenomena could be caused by the intrusion of mantle material, indicating the Tanlu fault could be just as the uprising channel of deep materials. 相似文献
20.
基于覆盖盐源盆地的短周期天然地震台阵和布设的一条人工地震测线所获得的地震数据,从中提取地震能量属性,并通过地震层析成像获得该地区的浅部地震速度结构,继而对短周期地震台阵一个月的噪声数据进行互相关得到经验格林函数,再通过时频分析获得相速度频散曲线,反演获得不同深度的S波速度分布。研究结果显示,盐源盆地地震特征主要分为三层:浅部为低速新生代沉积地层,P波速度为1.0—2.1 km/s,反射轴明显、连续性好,反射能量强,S波速度为中高南低,南部低速体与盐源断裂走向一致,新生代盆地整体呈南深北浅,沉积发育和构造形态受盐源断裂控制;中部为中低速三叠系地层,P波速度为3.5—4.5 km/s,反射轴不连续,反射能量较弱,S波速度逐渐变大,整体变化变小;深部为高速古生代地层,地震反射较为杂乱,反射能量弱;上地壳存在滑脱面,该界面为沉积盖层与结晶基底的分界面,且向浅部发育一系列断层,其中金河—箐河断裂为盐源盆地与康滇地块的分界线,这些断裂带也是盐源盆地地震频发的部位。 相似文献