共查询到18条相似文献，搜索用时 124 毫秒
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利用Incorporated Research Institutions for Seismology (IRIS)提供的远场宽频带P波及SH波记录,基于点源模型及有限断层模型方法,反演研究了2008年10月5日发生在中国天山与塔吉克斯坦交界区域的一次MS6.7级地震震源机制.结果表明,本次地震为南倾高角度稍具小幅度走滑分量的逆冲破裂事件,断层走向为57.2°,倾角为42.7°,震源深度为7.4 km.根据研究结果,我们认为这是一次逆断层加小幅度走滑分量的地震事件,推断该地震可能与帕米尔向北北西方向挤压西南天山,在帕米尔-西南天山边界引发的逆冲断层活动有关. 相似文献
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使用汇集在四川台网中心的固定台站、震后架设的流动台站、周边水库台站等震中距150 km以内的震相数据,选用分层速度模型,对芦山7.0级地震及震后9天内的余震利用双差定位法进行了重新定位.给出了芦山7.0级地震的发震时刻为2013-04-20 08:02:46.8,震中位置30.278°N,102.989°E,震源深度16.67 km,给出了3324次余震的双差定位结果,并对发震构造进行了分析.结果表明:芦山地震主破裂长度约40 km,下倾宽度约20 km,破裂视面积约800 km2,主破裂沿南西走向,倾角约40°.余震震源优势深度为10~22 km.余震沿南西走向,主要集中于大邑-名山断裂上盘. 相似文献
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中国西部地区是地震活动十分强烈的地区,天山、阿尔泰、帕米尔和西昆仑都是著名的地震构造带,在这些地震构造带和周边地区发生了多次震级大于5级的强震.本文通过分析西部地区的重力场特征,根据重力数据结合地震剖面、应用Parker-Oldenburg方法反演得到了研究区莫霍面深度,通过对比地震层析成像的反演结果,分析了研究区的地壳结构特征.计算结果表明,研究区地壳结构不均匀特征明显,在造山带地区一般是莫霍面坳陷区,盆地则是莫霍面隆起区,主要造山带地壳速度结构表现为高速区,盆地和主要凹陷区为低速区.根据计算结果和以往强震震中位置分析了地壳构造与强震活动的相关性,西部地区的地震活动与地壳结构的横向不均匀密切相关,强震主要发生在地壳速度变化带附近和地壳速度结构差异较大的地区,在构造应力作用下,这些地壳介质非均匀地区易发生强震,这是中国西部造山带和盆-山边界附近频发强震的构造原因之一. 相似文献
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本文基于中国数字地震台网记录到的2016年1月12日发生于兴都库什—帕米尔地区的中源地震P波宽频带波形资料,利用P波三重震相方法研究了中天山和塔里木盆地北部410 km间断面起伏形态及间断面附近P波速度结构.通过波形拟合,我们发现中天山和塔里木盆地北部410 km间断面下沉约10 km;410 km间断面上方存在由塔里木盆地向中天山P波速度异常逐渐减小的约70 km厚的低速层(-3%~-1%).该低速层可能是地幔转换区物质上涌并部分脱水熔融及热效应共同作用的结果.另外我们发现中天山东北部约10~100 km深度范围内存在局部低速异常(约-6%),其很可能是上涌的软流圈物质. 相似文献
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本文利用中国地震台网及ISC提供的区域地震和远震的P波走时数据,重建了中国大陆及其邻近地区的三维速度图象。 主要结果是:1.本文给出的速度图象揭示了中国大陆及其邻近地区的地壳和上地幔速度存在明显的横向不均匀性,这种不均匀性甚至在下地幔的1100km深度还依然存在。上地幔的速度图象同地表已知的地质构造特征的相关性可以追踪到110km,从220km以下很难找到它们之间的明显关系。2.45-0km和45+0km深度处的速度图象明显地表示出中国大陆的地壳厚度可以102.5°E附近为界分为两部分:其东部地壳薄,厚度都小于45km;西部有一条自若尔盖-松潘（34°N,102.5°E附近）向西北沿38°N往西至塔里木盆地南缘的分界线;其南部除滇西南之外,整个青藏高原的地壳厚度都大于45km;其北部除天山山脉之外,地壳厚度一般不大于45km.3.110km深度处的速度图象表明,速度异常呈块状分布。同中国大地构造分区略图比较之后发现,其中,扬子准地台和塔里木地台对应于高速区,中朝准地台则大都表现为低速异常;华南褶皱系为低速区,青藏地块南缘喜马拉雅和冈底斯念青唐古拉褶皱系则表现为高速异常。4.220km深度处的速度图象表明,中国大陆相当多的地区软流层有明显的显示。5.同450km和45+0km的速度图象一样,400km和600km的速度图 相似文献
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利用甘肃东南部地区(32.2°~33.5°N,102.7°~105.5°E)62个流动台站的垂直分量连续背景噪声记录数据,经过处理得到了所有可能台站对的面波互相关函数和瑞利波相速度频散曲线,采用基于射线追踪的面波频散直接反演方法得到了观测台站下方5~20km深度范围内的剪切波速度分布图像。结果表明,5km深度对应的剪切波速度横向变化与地表断裂带分布和沉积层厚度存在一定的相关性,西秦岭北缘断裂带以北地区多为低速区,漳县盆地、临洮盆地低速是沉积层较厚(近几km)的一种表征;10km深度对应的剪切波速度在西秦岭北缘断裂以南、临潭—宕昌断裂、礼县—罗家堡断裂之间的区域为低速区,光盖山—迭山北麓断裂周围为高速区;在15km深度左右,迭部—白龙江断裂附近形成了高低速相间的分块结构;在18km深度左右,西秦岭北缘断裂带附近呈现高速特征,10~18km深度范围内速度随深度逐渐增加,其变化幅度一般为0.2km/s。 相似文献
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利用位于新疆帕米尔东北缘地带12个固定数字地震台和天山动力学Ⅱ期10个流动宽频带数字地震台记录的高质量远震波形数据,应用接收函数H-κ叠加方法研究了帕米尔东北缘的地壳厚度-泊松比特征和部分台站下方的壳内界面深度.研究发现:(1) 帕米尔东北缘的Moho面起伏变化剧烈,其总体分布呈现东薄西厚、南厚北薄的特征,由塔里木盆地向天山延伸,地壳厚度约从45 km加深到55 km,从塔里木盆地向西昆仑山延伸,地壳厚度约从45 km加深到69 km;(2)沿着天山动力学Ⅱ期剖面,位于塔里木盆地北缘台站的壳内间断面的深度约为13~16 km,向北进入天山南麓加深到20 km左右,继续向北进入南天山山区壳内间断面不明显,可能暗示塔里木盆地基底向北俯冲,俯冲距离可能到达南天山的山前;(3)研究区地壳泊松比变化复杂(约从0.20到0.31),显示地壳物质组成的复杂性和显著的不均匀构造;(4)整个研究区的地壳厚度和泊松比之间没有明显的相关性,但天山动力学Ⅱ期剖面的结果表明,从塔里木盆地北缘到西南天山,地壳厚度和泊松比之间存在反相关关系,意味着天山地壳的增厚可能主要是通过以长英质岩石为主要组成成分的上地壳叠置而成;(5) 研究区全部地震台地壳厚度与海拔高程的线性回归方程表明地壳厚度与海拔的相关性相对较弱(相关系数为0.66),天山动力学Ⅱ期10个台站的地壳厚度与海拔具有很好的相关性(相关系数为0.85),可能表明沿该剖面地壳整体上处于相对均衡的状态. 相似文献
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采用震源位置及速度结果的联合反演方法确定闽粤赣交界区(24°~26.5°N,114°~117.8°E)地震的震源位置以及震源区速度结构。结果显示:1闽粤赣交界区地震震源平均深度随震级增大而加深的特征明显,即地震震级越大,震源深度越深,但平均深度不超过15 km;越靠近沿海,地震震源深度有加深的趋势。2通过对河源地区、邵武-河源断裂带中段(寻乌-瑞金)区域、政和-大浦断裂带中段(漳平附近)区域以及闽粤近海区域地震剖面研究,发现地震多发生于高低速异常结合部位。 相似文献
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根据欧亚大陆及西太平洋地区58个数字地震台站约12000个长周期波形记录,挑选出4100条面波大圆传播路径,采用面波频散及波形拟合反演方法,对东亚及西太平洋边缘海地区(60°E-160°E,20°S-60°N)的地壳上地幔进行了高分辨率三维S波速度成像. 结果表明,从上地壳到70km深,在东亚东部及西太平洋边缘海地区为高速分布,西部以青藏高原为中心呈极低速分布. 自地中海经土耳其、伊朗、喜马拉雅山到缅甸、印尼群岛的特提斯汇聚碰撞带,显示为低速异常链. 从85km至250km深,在东亚东部及西太平洋边缘海,自北向南显示出一条巨型低速异常带,西部地区为高速异常分布.以东经110°E为界,东西两部分岩石圈、软流圈的结构与深部动力过程有着巨大的差异. 此界线以西主要是印度板块与欧亚板块碰撞引起的岩石圈汇聚增厚区,东部则主要是由于软流圈上涌(地幔热物质上升)引起的岩石圈拉张减薄区. 相似文献
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JOINT INVERSION OF SURFACE WAVE DISPERSION AND RECEIVER FUNCTIONS FOR CRUSTAL AND UPPERMOST MANTLE STRUCTURE BENEATH CHINESE TIENSHAN AND ITS ADJACENT AREAS 
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下载免费PDF全文 The Tienshan orogenic belt is one of the most active intracontinental orogenic belts in the world. Studying the deep crust-mantle structure in this area is of great significance for understanding the deep dynamics of the Tienshan orogen. The distribution of fixed seismic stations in the Tianshan orogenic belt is sparse. The low resolution of the existing tomographic results in the Tienshan orogenic belt has affected the in-depth understanding of the deep dynamics of the Tienshan orogenic belt. In this paper, the observation data of 52 mobile seismic stations in the Xinjiang Seismic Network and the 11 new seismic stations in the Tienshan area for one-year observations are used. The seismic ambient noise tomography method is used to obtain the Rayleigh surface wave velocity distribution image in the range of 10~50s beneath the Chinese Tienshan and its adjacent areas (41°~48° N, 79°~91° E). The joint inversion of surface wave and receiver function reveals the S-wave velocity structure of the crust and uppermost mantle and the crustal thickness below the station beneath the Chinese Tienshan area(41°~46° N, 79°~91° E). The use of observation data from mobile stations and new fixed seismic stations has improved the resolution of surface wave phase velocity imaging and S-wave velocity structure models in the study area.
The results show that there are many obvious low-velocity layers in the crust near the basin-bearing zone in the northern Tienshan Mountains and the southern Tienshan Mountains. There are significant differences in the structural characteristics and distribution range of the low-velocity zone in the northern margin and the southern margin. Combining previous research results on artificial seismic profiles, receiver function profiles, teleseismic tomography, and continental subduction simulation experiments, it is speculated that the subduction of the Tarim Basin and the Junggar Basin to the Tienshan orogenic belt mainly occurs in the middle of the Chinese Tienshan orogenic belt, and the subduction of the southern margin of the Tienshan Mountains is larger than that of the northern margin, and the subduction of the eastern crust is not obvious or in the early subduction stage. There are many low-velocity layers in the inner crust of the Tienshan orogenic belt, and most of them correspond to the strong uplifting areas that are currently occurring. The thickness of the crust below the Tienshan orogenic belt is between 55km and 63km. The thickness of the crust(about 63km)is the largest near the BLT seismic station in the Bazhou region of Xinjiang. The average crustal thickness of the Tarim Basin is about 45km, and that of the Junggar Basin is 47km. The S-wave velocity structure obtained in this study can provide a new deep basis for the study of the segmentation of the Tienshan orogenic belt and the difference of the basin-mountain coupling type. 相似文献
The results show that there are many obvious low-velocity layers in the crust near the basin-bearing zone in the northern Tienshan Mountains and the southern Tienshan Mountains. There are significant differences in the structural characteristics and distribution range of the low-velocity zone in the northern margin and the southern margin. Combining previous research results on artificial seismic profiles, receiver function profiles, teleseismic tomography, and continental subduction simulation experiments, it is speculated that the subduction of the Tarim Basin and the Junggar Basin to the Tienshan orogenic belt mainly occurs in the middle of the Chinese Tienshan orogenic belt, and the subduction of the southern margin of the Tienshan Mountains is larger than that of the northern margin, and the subduction of the eastern crust is not obvious or in the early subduction stage. There are many low-velocity layers in the inner crust of the Tienshan orogenic belt, and most of them correspond to the strong uplifting areas that are currently occurring. The thickness of the crust below the Tienshan orogenic belt is between 55km and 63km. The thickness of the crust(about 63km)is the largest near the BLT seismic station in the Bazhou region of Xinjiang. The average crustal thickness of the Tarim Basin is about 45km, and that of the Junggar Basin is 47km. The S-wave velocity structure obtained in this study can provide a new deep basis for the study of the segmentation of the Tienshan orogenic belt and the difference of the basin-mountain coupling type. 相似文献
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在沙城以东的延庆盆地及其邻近区域内布设了由GDS－1000宽频带数字地震仪组成的流动地震台阵，利用台阵记录的宽频带远震P波波形数据和非线性接收函数反演方法获得了延怀盆地内0-80km深度范围的地壳、上地幔S波速度结构．利用计算机三维彩色剖分显示技术研究了台阵下地壳、上地幔速度结构的横向非均匀变化。结果表明，研究区域内的地壳厚度为40km左右，壳幔界面有4km左右的上下起伏．地表沉积盖层在延庆盆地中心附近厚度约1km，而在向盆地外围延伸的方向上相对变薄．研究区域内上地壳S波速度结构较复杂，而下地壳与上地幔则相对比较均匀．其上地壳最突出的特点是在10km深度附近有明显的S波低速层．在延庆盆地下方，它延伸到6-20km的深度范围．在延庆盆地南侧，该低速层有从西往东逐渐减弱的趋势．研究区域内的地震基本上都发生在延庆盆地下方上地壳低速体外围．据此推断，延庆盆地及其临近区域内的地震活动与该区域地壳内的热状态有密切关系． 相似文献
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THREE-DIMENSIONAL S-WAVE VELOCITY DISTRIBUTION BASED ON AMBIENT NOISE ANALYSIS IN EASTERN NORTH 下载免费PDF全文
下载免费PDF全文 We apply ambient noise tomography to continuous vertical component broadband seismic data between January 1, 2010 and December 31, 2011from the regional networks of 190 stations deployed by China Earthquake Administration in Hebei, Shanxi and Inner Mengolia. Ambient noise cross-correlations were performed to produce the Green's functions of each station-pair. Firstly, we used the multiple-filter analysis method to extract surface wave group and phase velocity dispersion curves from inter-station paths at periods from 7 to 40s. Then the study area was discretized into a 0.2°×0.2° grid to obtain the group and phase velocity distributions using O'ccam inversion method. After that, three dimensional (3-D) S-wave velocity structures from the surface down to 50km are inverted from group and phase velocities dispersion results. the results of S wave velocity distribution maps generally demonstrate good correlations with surface geological and tectonic features, and they also clearly revealed the lateral velocity variation in the crust. In the mid-upper crust, the basins are clearly resolved with low S wave velocity due to its thick sedimentary layer, and the Taihang and Yanshan uplifts show relative higher S wave velocity distribution. With the increase of depth (>30km), the S wave velocity distribution presents a contrary characteristic compared to that of the shallow layer, and the S wave velocity beneath the Taihang and Yanshan uplifts are much lower than basin areas, which is possibly correlated with the thickness of the crust. 3-D S wave velocity shows a low-velocity zone at~10~20km depth observed beneath the Tanshan-Hejian-Xintai-Cixian belt and Bohai Bay. the low-velocity zone at~20~30km depth beneath the Datong area may be associated with the thermal material in the crust-mantle. Our S wave velocity distribution maps clearly show that Taihang Mountains is not only the boundary of topography and tectonic zone, but also the transition zone of high and low S wave velocity. 相似文献
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IntroductionSouthwestern China and its adjacent areas studied in the paper is the range of 10(N-36(N, 70(E-110(E, which includes southwestern areas of China (Sichuan, Xizang, Yunnan, Guizhou, Guangxi Provinces, southwestern Shaanxi Province and so on), India, Myanmar, Thailand, Vietnam, Laos and Cambodia countries and oceanic areas of Bay of Bengal and Beibu Gulf. The collision and extrusion of India plate and Eurasia plate makes the geological tectonic complex in this area (Figure 1… 相似文献
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利用华北地震科学台阵和首都圈地震台网记录的4511次近震和625次远震的P波到时数据,采用纬度和经度方向分别为0.5°×0.5°的网格划分,反演得到了华北北部地区(111°E—120°E,37°N—42°N)深至400km的地壳上地幔三维P波速度结构.层析成像结果表明,研究区的速度存在明显的横向不均匀性,随着深度增加横向不均匀性总体呈现减弱趋势.燕山隆起带在60—120km深度内存在明显的高速异常,这与较大的岩石圈厚度有关;山西裂陷盆地、华北平原下方60km深度存在明显低速异常,与软流圈的出现有关.燕山隆起带岩石圈厚度在120km以上,明显比太行山隆起的岩石圈厚度大,与稳定大陆地区的岩石圈厚度一致.太行山山前断裂已切穿莫霍面,贯入岩石圈.研究区上地幔顶部大范围的低速异常反映了软流圈上隆的特点.在华北平原及燕山隆起下方200—300km存在高速异常可能与太古代大陆板块岩石圈的残留体有关. 相似文献
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收集和拾取了“中国地震科学台阵”探测项目在南北地震带北段布设的680个流动地震台站和中国地震台网217个固定台站所记录的地震事件的P波和S波初至到时，通过层析成像研究获得了南北地震带北段水平网格间距为0.33°×0.33°的地壳P波和S波速度分布。结果显示:在30 km深度上青藏高原东北部表现为显著的整体性低速异常，低速异常区向南延伸至龙门山断裂，以106°E为界线将秦岭造山带分为西侧的低速异常和东侧的高速异常，并沿银川—河套地堑向东北展布，向北穿过河西走廊，在阿拉善地块表现为低速异常，这可能暗示了青藏高原向东的扩展被较为坚固的四川盆地和秦岭造山带阻挡，而向北的扩展可能影响到了河西走廊至阿拉善地块，并沿银川—河套地堑影响到鄂尔多斯西北缘；在50 km深度上，阿拉善地块、祁连造山带东段显示高速异常，有可能是阿拉善地块向祁连东段下方俯冲所致。研究区内大部分地震分布在P波和S波高低速异常相间及速度剧烈变化的地区，M≥6.0强震几乎全部投影在30 km深度的低速异常区域内，说明强震发生的背景可能与地震源区下方的低速区有关。 相似文献
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搜集了青藏高原及其邻近区域的S波速度三维层析成像结果和2万多个实测重力点资料，将重力资料进行各种改正并网格化为30′×30′的布格重力异常．首先采用密度差与S波速度差之间的经验关系式，建立青藏地区岩石层密度的初始模型，再利用布格重力异常进行阻尼最小二乘法反演，得到青藏地区岩石层三维密度分布结果．反演结果表明：（1）青藏高原岩石层密度分布不仅在纵向上不均匀，而且在横向存在明显的不均匀．在深度10－70km范围内，高原整体呈低密度特性，在50－70km深度范围内低密度特征更加突出，与周缘地区存在0，1g／cm3的密度差．而在90－110km深度范围内，高原岩石层地幔显示密度高．（2）岩层密度分布与大地构造有明显相关的分区性，显示出青藏块体、巴颜喀拉块体、塔里木块体和印度块体． 相似文献