Tunnel effect of fractal fault and transient S-wave velocity rupture (TSVR) of in-plane shear fault

ｎｔｒｏｄｕｃｔｉｏｎＴｒａｎｓｉｅｎｔＳｗａｖｅｖｅｌｏｃｉｔｙｒｕｐｔｕｒｅ（ＴＳＶＲ）ｍｅａｎｓｔｈｅｖｅｌｏｃｉｔｙｖｏｆｆａｕｌｔｒｕｐｔｕｒｅｉｓｂｅｔｗｅｅｎＳｗａｖｅｖｅｌｏｃｉｔｙβａｎｄＰｗａｖｅｖｅｌｏｃｉｔｙα．Ｉｔｓｅ...     

Velocity structure of the crust and upper mantle in Xingtai earthquake region and its adjacent area

ＶｅｌｏｃｉｔｙｓｔｒｕｃｔｕｒｅｏｆｔｈｅｃｒｕｓｔａｎｄｕｐｐｅｒｍａｎｔｌｅｉｎＸｉｎｇｔａｉｅａｒｔｈｑｕａｋｅｒｅｇｉｏｎ　ａｎｄ　ｉｔｓａｄｊａｃｅｎｔａｒｅａＺｈｉ－ＰｉｎｇＺＨＵ；（祝治平）Ｘｉａｎ－ＫａｎｇＺＨＡＮＧ；（张称康）Ｙｕ...     

Reflection and transmission of seismic waves at an interface betwen two saturated soils

ＲｅｆｌｅｃｔｉｏｎａｎｄｔｒａｎｓｍｉｓｉｏｎｏｆｓｅｉｓｍｉｃｗａｖｅｓａｔａｎｉｎｔｅｒｆａｃｅｂｅｔｗｅｎｔｗｏｓａｔｕｒａｔｅｄｓｏｉｌｓＪＵＮＹＡＮＧ（杨峻）ＳＨＩＭＩＮＧＷＵ（吴世明）ＺｈｅｊｉａｎｇＵｎｉｖｅｒｓｉｔｙ，Ｈａｎｇｚ...     

The effect of local irregular topography on seismic ground motion

Ｔｈｅｅｆｆｅｃｔｏｆｌｏｃａｌｉｒｒｅｇｕｌａｒｔｏｐｏｇｒａｐｈｙｏｎｓｅｉｓｍｉｃ　ｇｒｏｕｎｄ　ｍｏｔｉｏｎＪＩＧ－ｈｏＬＩＵ（刘晶波）（ＤｅｐａｒｔｍｅｎｔｏｆＣｉｖｉｌＥｎｇｉｎｅｅｒｉｎｇ，ＴｓｉｎｇｈｕａＵｎｉｖｅｒｓｉｔｙＢｅｉｊｉ...     

Study on crust-mantle tectonics and its velocity structure along the Beijing-Huailai-Fengzhen profile

ｔｕｄｙｏｎｃｒｕｓｔｍａｎｔｌｅｔｅｃｔｏｎｉｃｓａｎｄｉｔｓｖｅｌｏｃｉｔｙｓｔｒｕｃｔｕｒｅａｌｏｎｇｔｈｅＢｅｉｊｉｎｇＨｕａｉｌａｉＦｅｎｇｚｈｅｎｐｒｏｆｉｌｅＺＨＩＰＩＮＧＺＨＵ（祝治平）ＸＩＡＮＫＡＮＧＺＨＡＮＧ（张先康）...     

The fine velocity structure of sediment－base－ment layer in the Three－GorgesRegionoftheChangjiangRiver（YangtzeRiver）

Ｔｈｅｆｉｎｅｖｅｌｏｃｉｔｙｓｔｒｕｃｔｕｒｅｏｆｓｅｄｉｍｅｎｔ┐ｂａｓｅ┐ｍｅｎｔｌａｙｅｒｉｎｔｈｅＴｈｒｅｅ┐ＧｏｒｇｅｓＲｅｇｉｏｎｏｆｔｈｅＣｈａｎｇｊｉａｎｇＲｉｖｅｒ（ＹａｎｇｔｚｅＲｉｖｅｒ）ＨＯＮＧ－ＸＩＡＮＧＨＵ（胡鸿翔），...     

The b value spectrum and η value by the moment method

ＴｈｅｂｖａｌｕｅｓｐｅｃｔｒｕｍａｎｄηｖａｌｕｅｂｙｔｈｅｍｏｍｅｎｔｍｅｔｈｏｄＴｏｒｕＯｕｃｈｉ（大内）ＤｅｐａｒｔｍｅｎｔｏｆＥａｒｔｈＳｃｉｅｎｃｅｓ，ＦａｃｕｌｔｙｏｆＳｃｉｅｎｃｅ，ＫｏｂｅＵｎｉｖｅｒｓｉｔｙ，Ｋｏｂｅ，６５７，...     

Contributors to this issue

Ｇｕｏ－ＭｉｎＺＨＡＮＧ（张国民）ＧｏｔＢａｃｈｅｌｏｒａｎｄＭａｓｔｅｒＤｅｇｒｅｅｓｉｎＧｅｏｐｈｙｓｉｃａｌＤｅｐａｒｔｍｅｎｔ，ｔｈｅＳｃｉｅｎｃｅａｎｄＴｅｃｈｎｏｌｏｇｙＵｎｉｖｅｒｓｉｔｙ．ｏｆＣｈｉｎａｉｎ１９６５ａｎｄ１９６８ｒｅｓ...     

Temporal variations of coda Q~（－1） associated with the dahaituoshan， Beijing， earthquake of 1990

Ｐｒｅｓｅｎｔａｄｄｒｅｓｓ：ＳｏｕｔｈＣａｌｉｆｏｒｎｉａＵｎｉｖｅｒｓｉｔｙ，ＵＳＡ．ＣｏｎｔｒｉｂｕｔｉｏｎＮｏ．９３Ａ００３２，ＩｎｓｔｉｔｕｔｅｏｆＧｅｏｐｈｙｓｉｃｓ，ＳＳＢ，Ｃｈｉｎａ．ａｎｄｓｔａｔｉｏｎａｒｅｓｅｐａｒａｔｅ，ｓｕｐｐｏｓｉｎｇａｒａｎｄｏｍａｎｄｈｏｍｏｇｅｎｅｏｕｓｄｉｓｔｒｉｂｕｔｉｏｎｏｆｔｈｅｓｃａｔｔｅｒｓｉｎａｔｈｒｅｅ－ｄｉｍｅｎｓｉｏｎａｌｉｎｆｉｎｉｔｅａｎｄｐｅｒｆｅｃｔｌｙｅｌａｓｔｉｃｍｅｄｉｕｍ．ＴｈｅｅｎｅｒｇｙｄｅｎｓｉｔｙａｔａｄｉｓｔａｎｃｅｏｆｒｉｓｇｉｖｅｎａｓＥ（ｒ，ｔ｜ω）＝［Ｗ０（ω）ｇ０（ω）］／（４πｒ２）．Ｋ（ｖｔ／ｒ）．ｅｘｐ（－ωＱｃ－１ｔ）ｖｔ＞ｒ（２）ＷｈｅｒｅＫ（ｘ）＝（１／ｘ）ｌｎ［（ｘ＋１）／（ｘ－１）］，ａｎｄｇ０（ω）ｉｓｔｈｅｔｏｔａｌｓｃａｔｔｅｒｉｎｇｃｏｅｆｆｉｃｉｅｎｔｃｈａｒａｃｔｅｒｉｚｉｎｇａｓｃａｔｔｅｒｉｎｇｐｏｗｅｒｐｅｒｕｎｉｔｖｏｌｕｍｅｏｆｔｈｅｈｏｍｏｇｅｎｅｏｕｓｍｅｄｉｕｍ．Ｃｏｍｐａｒｉｓｏｎｏｆｖａｒｉｏｕｓｏｂｓｅｒｖａｔｉｏｎｓｉｎｃｌｕｄｉｎｇｃｏｄａｄｅｃａｙ     

Method of expected earthquake losses estimation based on the frequency of seismic site intensity

Ｍｅｔｈｏｄｏｆｅｘｐｅｃｔｅｄｅａｒｔｈｑｕａｋｅｌｏｓｓｅｓｅｓｔｉｍａｔｉｏｎｂａｓｅｄｏｎｔｈｅｆｒｅｑｕｅｎｃｙｏｆｓｅｉｓｍｉｃｓｉｔｅｉｎｔｅｎｓｉｔｙ高孟潭Ｍｅｎｇ－ＴａｎＧＡＯ（ＩｎｓｔｉｔｕｔｅｏｆＧｅｏｐｈｙｓｉｃｓ,Ｓｔａｔｅ...     

A study on 3-D velocity structure of crust and upper mantle in Sichuan -Yunnan region, China

Many evidences indicate that the collision of two plates deformed strongly the crust of the SYR, and the deformation has been continued up to the present. In addition, the SYR is in the south segment of the South-North Seismic Zone of China, which is one of the regions in the Chinese mainland, where the seismic activity is very high, and the strong earthquakes frequently occurred. Since the 1970s, a series of large earthquakes with magnitude M>7.0 occurred in SYR, such as the 1970 Tongha…     

郯庐断裂带鲁苏皖段及邻区上地幔顶部Pn波速度与各向异性

为着重探讨郯庐断裂带鲁苏皖段的分段特征及其深部结构特征,本研究搜集增加了研究区内近几年的Pn震相数据.经挑选后采用了由2163个地震和301个台站构成的9156条射线,重新反演构建了郯庐断裂带鲁苏皖段及邻区上地幔顶部Pn波速度及方位各向异性分布.尔后,将速度反演结果与地形地貌、大地热流、强震活动及地壳厚度等进行了综合对比和分析;此外,还将Pn波各向异性与地震各向异性其他观测手段的结果展开了对比和讨论.反演结果的可靠性和分辨能力较前文有所提高,研究区上地幔顶部的非均匀性特征揭露得更为清楚,尤其是由Pn波速度揭露的郯庐断裂带分段特征与地质构造特征吻合得更佳.结果表明:(1)Pn波高、低速的分布与地形地貌呈负相关的关系,即山地隆起区呈低速分布,而平原地区表现为高速异常.(2)Pn波速度沿郯庐断裂带的分布具有明显的分段特征,本文的研究结果支持郯庐断裂带在研究范围内的上地幔顶部可细分为4个亚段.由上地幔顶部Pn波速度揭示的郯庐带分段特征与前人根据郯庐断裂带各段的地表地质构造特征给出的分段结果吻合,深、浅耦合的现象表明郯庐断裂带是一条贯穿地壳、深抵Moho面的幔源深大断裂带.(3)Pn波速度与大地热流呈负相关的关系.(4)Pn波速度的分布与强震的发生具有一定的关联性,强震大部分发生在Pn波高、低速过渡地带或者低速区域的地壳内.(5)在南黄海海域新发现一条NNE-SSW向展布的弱高波速异常带,该异常带被强震震中清晰地勾勒了出来,据此推测其下方存在一条切割Moho界面的幔源深大断裂.(6)Pn波各向异性的强弱与地质构造的活动性相关,活动性越强则各向异性强度越大.(7)由地震台站的时间延迟分布可以看出,研究区地壳厚度总体上自SE往NW逐渐增厚;最大厚度位于渤海湾盆地的北西部和西部.     

川滇地区地壳上地幔三维速度结构研究

根据云南和四川地震台网174个台站记录的4625个区域地震初至Ｐ波和Ｓ波走时资料，并结合其它深部地球物理资料，确定了川滇地区地壳上地幔三维速度结构．在上地壳速度异常分布中，四川盆地为正异常，川西高原为负异常，龙门山断裂带为正、负异常的边界．龙门山断裂、鲜水河断裂以及红河断裂等，在下地壳和上地幔的速度异常中仍显示出构造分界特征，说明它们可能穿透了莫霍界面．腾冲火山区和攀西构造带在50km深度上呈现负速度异常，与上地幔温度和物质组成的差异相联系．川滇地区地壳结构的总体特征是:地壳和上地幔的低平均速度，地壳厚度变化剧烈，地壳和（或）上地幔存在高导层、高热流值．这些同印度板块与欧亚板块碰撞的构造背景有关．川滇菱形块体在地壳内总体上为正常或正异常速度，而其边界的深大走滑断裂存在负速度异常，它有助于地壳块体沿断裂的侧向挤出．在主要的地震带上，中下地壳的负速度异常与地震活动性相关．多数强烈地震发生在具有正速度异常或正常速度分布的上中地壳深度上，而其下方则通常是负速度异常带．      

南海东北部海陆深地震联测与滨海断裂带两侧地壳结构分析

南海东北部首次成功实施海陆联合深地震探测,填补了海陆过渡带深地震探测的空白. 利用该次海陆联测地震数据,通过数据处理、震相分析、射线追踪、走时模拟等方法,获得了滨海断裂带附近的纵波地壳速度结构,探明了海陆联测剖面中滨海断裂带可能位置. 地壳速度结构为陆壳结构,地壳厚度由陆地向海区逐步变薄;在上地壳下部普遍存在一层速度为5.5～5.9km·s-1、厚度为2.5～4.0km的低速层,并向海区方向减薄,该区未发现明显的高速层. 滨海断裂带为一纵向低速带,位于南澳台东南35km处,对应于重、磁异常带,断裂带断至莫霍面,是华南陆区正常型陆壳与海区减薄型陆壳的分界地壳断裂.     

古雷—石城地区地壳与上地幔地震波速度结构及莫霍面特征

本文是1986年古雷—石城剖面及嵩口—宜城剖面深地震测深资料的初步研究结果。 对古雷—石城的纵剖面资料,分析了震相特征,共识别出五个波组:P_2、P_3~0、P_4~0、P_5~0及P_n(P_n~0)。通过对波的走时反演,正演拟合和理论地震图方法等计算,得到了该区地壳与上地幔结构模型。 古雷—石城地区地壳具有多层结构,并可划分为上、中、下三层。古雷炮点给出的厚度分别为1.0km、15.7km、12.8km,地壳平均速度为6.29km/s,深度为29.5km,上地幔顶面P_n波速度为7.83km/s。石城炮点给出厚度分别为1.8km、18.3km、12.4km。地壳平均速度为6.29km/3,深度为32.4km,土地幔顶面P_n速度为8.00km/s。 在中地壳下部存在一低速层,其厚度为2.8km,速度为5.85km/s。根据其它研究结果,初步判断低速层介质是半熔融物质组成。 测区内横向变化比较强烈。从东向西有长乐—诏安、政和—海丰和邵武—河源三个大断裂穿过该区,并且都深切至莫霍面;在漳州盆地之下莫霍面隆起约3km,戴云山区下莫霍面凹陷近2km;永安—梅州莫霍面隆起接近3km。莫霍面分布显示出从东南向西北逐渐加深。 宜城—连城—嵩口非纵剖面显示了莫霍面在两处有明显断错,错距约2km邵。表明昭武—河源断裂是切割莫霍面的深大断裂。     

A study on 3-D velocity structure of crust and upper mantle in Sichuan-Yunan region, China

Based on the first arrival P and S data of 4 625 regional earthquakes recorded at 174 stations dispersed in the Yunnan and Sichuan Provinces, the 3-D velocity structure of crust and upper mantle in the region is determined, incorporating with previous deep geophysical data. In the upper crust, a positive anomaly velocity zone exists in the Sichuan basin, whereas a negative anomaly velocity zone exists in the western Sichuan plateau. The boundary between the positive and negative anomaly zones is the Longmenshan fault zone. The images of lower crust and upper mantle in the Longmenshan fault, Xianshuihe fault, Honghe fault and others show the characteristic of tectonic boundary, indicating that the faults likely penetrate the Moho discontinuity. The negative velocity anomalies at the depth of 50 km in the Tengchong volcanic area and the Panxi tectonic zone appear to be associated with the temperature and composition variations in the upper mantle. The overall features of the crustal and the upper mantle structures in the Sichuan-Yunnan region are the lower average velocity in both crust and uppermost mantle, the large crustal thickness variations, and the existence of high conductivity layer in the crust or/and upper mantle, and higher geothermal value. All these features are closely related to the collision between the India and the Asia plates. The crustal velocity in the Sichuan-Yunnan rhombic block generally shows normal value or positive anomaly, while the negative anomaly exists in the area along the large strike-slip faults as the block boundary. It is conducive to the crustal block side-pressing out along the faults. In the major seismic zones, the seismicity is relative to the negative anomaly velocity. Most strong earthquakes occurred in the upper-mid crust with positive anomaly or normal velocity, where the negative anomaly zone generally exists below. Foundation item: National Scientific and Technological Development Program (95-973-02-02), the Climb Program (95-S-05-01) of National Scientific and Technological Ministry of China, and the State Natural Sciences Foundation of China (49874021). Contribution No. 02FE2004, Institute of Geophysics, China Seismological Bureau.     

台湾海峡大容量气枪震源海陆联测初探

本文利用在我国台湾海峡采用大容量气枪震源开展海陆联测获得的广角地震测线HX9, 采用二维射线追踪法反演得到了HX9剖面的地壳二维速度结构和地壳界面形态, 初步探明了福建—台湾海峡海陆过渡带的深部构造． 结果表明: HX9剖面的地壳内存在两个速度间断面, 即C界面和莫霍面, 其中: C界面为上、 下地壳的分界面, 是一个小的速度不连续面, 速度变化值达0.08—0.16 km/s; 而地壳底部的莫霍面则有较大的速度反差, 变化值达1.02—1.29 km/s, 莫霍面上、 下的速度分别为6.75—6.97 km/s和8.00—8.07 km/s． 沿剖面的地壳界面形态总体起伏不大, 陆域上、 下地壳的厚度和界面变化趋势均相似, 从陆域到海域呈微倾斜变化趋势, 表现为减薄陆壳的特征． 莫霍面陆域埋深约为31.6 km, 向福建东南沿海逐渐减薄至27.4 km左右．      

THE 3-D VELOCITY STRUCTURE OF CRUST AND UPPERMOST MANTLE AND ITS TECTONIC IMPLICATIONS IN FUJIAN PROVINCE

It is important to detect the fine velocity structures of the crust and uppermost mantle to understand the regional tectonic evolution, earthquake generation processes, and to conduct earthquake risk assessment. The inversion of uppermost mantle velocity and Moho depth are strongly influenced by crustal velocity heterogeneity. In this study, we collected first arrivals of Pg and Pn and secondary arrivals of Pg wave from the seismograms recorded at Fujian provincial seismic network stations. New 3-D P-wave velocities were inverted by multi-phase joint inversion method in Fujian Province. Our results show that the fault zones in Fujian Province have various velocity patterns. The shallow crust is characterized by high velocity that represents mountains, while the mid-lower crust shows low velocities. The anomalous velocities are correlated closely with tectonic faults in Fujian Province. Velocity anomalies mainly show NE-trending distribution, especially in the mid-lower crust and uppermost mantle, which is consistent with the NE-trending of the regional main fault zones. Meanwhile, a part of velocity patterns show NW trending, which is related to the secondary NW-oriented faults. Such velocity distribution also shows a geological structural pattern of "zoning in east-west direction and blocking in north-south direction" in Fujian area. In the crust, a low velocity zone is found along Zhenghe-Dapu fault zone as mentioned by previous study, however our result shows the low velocity exists at depth of 20~30km in mid-lower crust. Compared with previous study, this low velocity zone is larger and deeper both in range and depth. The crustal thickness of 28~35km from our joint inversion is similar to the results from the receiver functions of previous studies. The thinnest crust(28km)is observed at offshore in the north of Quanzhou; while the thickest crust(35km)is located west of Zhangzhou near the Zhenghe-Dapu fault zone. Generally, thinner crustal thickness is found in offshore of Fujian Province, and thicker crustal thickness is in the mainland. However, we also found that crustal thickness becomes thinner along the east side of Yongan-Jinjiang Fault. The values of Pn velocities in the region vary from 7.71 to 8.26km/s. The velocity distribution of the uppermost mantle presents a large inhomogeneity, which is correlated with the distribution of the fault zone. High Pn velocity anomalies are found mainly along the west side of the Zhenghe-Dapu fault zone(F₂), and the east side of the Shaowu-Heyuan fault zone(F₁), which is strip-shaped throughout the central part of Fujian. Low Pn velocity anomalies are observed along the coast and Taiwan Straits, including the Changle-Zhaoan fault zone, the coastal fault zone, and the Fuzhou Basin. We also found a low Pn velocity anomaly zone, which extends to the coast, in the Shaowu-Heyuan fault zone at the junction of the Fujian, Guangdong and Jiangxi Provinces. In the west of Taiwan Straits, both high and low Pn velocity anomalies are observed. Our results show that the historical strong earthquakes(larger than magnitude 6.0) are mainly distributed between positive and negative anomaly zones at different depth profiles of the crust, and similar anomalies distribution also exists at the uppermost mantle, suggesting that the occurrence of strong earthquakes in the region is not only related to the anomalous crustal velocity structure, but also affected by the velocity anomaly structure from the uppermost mantle.     

豫北及其外围地区地壳上地幔结构研究

利用菏泽～长治和郑州～济南深地震测深剖面资料，进行了一维、二维射线追踪走时拟合与合成地震图计算，获得了该区地壳上地幔速度结构。结果表明，地壳上地幔速度结构在纵向和横向上具有明显的不均一性。浅部断裂较发育，对应其地壳深部界面和速度等值线起伏变化较明显。在华北坳陷区南部上地幔隆起的背景上存在两个局部凸起，凸起最高处与浅部的东濮凹陷、汤阴地堑基本对应，Ｍ面埋深分别约３１ｋｍ和３４ｋｍ     

青藏高原东部及其边缘地区的地壳上地幔三维速度结构

利用在青藏高原东部及其邻近地区记录到的１万余条近震到时资料,反演该地区的地壳上地幔三维速度结构。采用网格点模型描述三维速度结构,模型维数为２２２２６,网格点间距水平向为１００ｋｍ,垂直向为２０ｋｍ,网格点之间的速度值通过线性插值给出。采用改进了的快速三维射线追踪方法,确定三维非均匀介质中的地震射线路径和理论走时。反演结果显示,青藏高原南部的上地壳中（３０ｋｍ左右的深度）存在一低速区,这和面波反演的结果一致,羌塘块体下地壳有明显的低速异常带,青藏公路沿线的垂直速度剖面显示出岩石层受挤压增厚的构造特征。