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1.
Vassilios Karakostas Eleftheria Papadimitriou Maria Mesimeri Charikleia Gkarlaouni Parthena Paradisopoulou 《Acta Geophysica》2015,63(1):1-16
The 2014 Kefalonia earthquake sequence started on 26 January with the first main shock (MW6.1) and aftershock activity extending over 35 km, much longer than expected from the causative fault segment. The second main shock (MW6.0) occurred on 3 February on an adjacent fault segment, where the aftershock distribution was remarkably sparse, evidently encouraged by stress transfer of the first main shock. The aftershocks from the regional catalog were relocated using a 7-layer velocity model and station residuals, and their distribution evidenced two adjacent fault segments striking almost N-S and dipping to the east, in full agreement with the centroid moment tensor solutions, constituting segments of the Kefalonia Transform Fault (KTF). The KTF is bounded to the north by oblique parallel smaller fault segments, linking KTF with its northward continuation, the Lefkada Fault. 相似文献
2.
利用四川省地震台网的震相数据和双差定位方法对芦山MS7.0级地震及其余震序列进行了精确定位,根据余震分布确定了发震断层的位置和断层面的几何特征,并对余震活动进行了分析.结果显示,芦山MS7.0级地震的震中位于30.28°N、102.99°E,震源深度为16.33 km.余震沿发震断层向主震两侧延伸,主要分布在长约32 km、宽约15~20 km、深度为5~24 km的范围内.地震破裂带朝西南方向扩展范围较大,东北方向略小,余震震级随时间迅速衰减.震源深度剖面清晰地显示出发震断层的逆冲破裂特征,推测发震断层为大川—双石断裂东侧约10 km的隐伏断层.该断层走向217°、倾向北西,倾角约45°,产状与大川—双石断裂相比略缓,它们同属龙门山前山断裂带的叠瓦状逆冲断层系.受发震断裂影响,部分余震沿大川—双石断裂分布,西北方向的余震延伸至宝兴杂岩体的东南缘,与汶川地震的破裂带之间存在50 km左右的地震空区,有可能成为未来发生强震的潜在危险区. 相似文献
3.
B. Papazachos A. Kiratzi B. Karacostas D. Panagiotopoulos E. Scordilis D. M. Mountrakis 《Pure and Applied Geophysics》1988,126(1):55-68
A shallow earthquake ofM
S=6.2 occurred in the southern part of the Peloponnesus, 12 km north of the port of the city of Kalamata, which caused considerable damage. The fault plane solution of the main shock, geological data and field observations, as well as the distribution of foci of aftershocks, indicate that the seismic fault is a listric normal one trending NNE-SSW and dipping to WNW. The surface ruptures caused by the earthquake coincide with the trace of a neotectonic fault, which is located 2–3 km east of the city of Kalamata and which is related to the formation of Messiniakos gulf during the Pliocene-Quaternary tectonics. Field observations indicate that the earthquake is due to the reactivation of the same fault.A three-days aftershock study in the area, with portable seismographs, recorded many aftershocks of which 39 withM
S1.7 were very well located. The distribution of aftershocks forms two clusters, one near the epicenter of the main shock in the northern part of the seismogenic volume, and the other near the epicenter of the largest aftershock (M
S=5.4) in the southern part of this volume. The central part of the area lacks aftershocks, which probably indicates that this is the part of the fault which slipped smoothly during the earthquake. 相似文献
4.
Dozens of >M5, hundreds of >M4, and much more >M3 aftershocks occurred after the 2008/05/12 Wenchuan earthquake, which were well recorded by permanent and portable seismic
stations. After relocated with P arrival, the >M3 aftershocks show two trends of distribution, with most of the aftershocks located along the north-east strike consistent
with Longmenshan fault system, yet there is a north-west trend around the epicenter. It seems that substantially more aftershocks
occur in regions with crystalline bedrocks. Then we collected waveform data from National Digital Seismograph Network and
regional seismograph network of China, and employed “Cut and Paste” method to obtain focal mechanisms and depths of the big
aftershocks (M⩾5.6). While most of those aftershocks show thrust mechanism, there are some strike slip earthquakes in the northern-most
end of the rupture. Focal mechanisms show that the events located on the southern part of central Beichuan-Yingxiu Fault (BY)
are mainly thrust earthquakes, which is consistent with initial mechanism of the main shock rupture. In the north part the
aftershocks along the BY are also dominated by thrust slip, which is quite different from the right slip rupture of the main
shock. Around Qingchuan-Pingwu Fault, the focal mechanisms are dominated by right-slip rupture with large depths (∼18 km).
So we suspected that in the north part the main shock might rupture on two faults: Beichuan Fault and Qingchuan-Pingwu Fault.
The complex pattern of aftershock mechanisms argues for presence of a complicated fault system in the Longmenshan area.
Supported by Knowledge Innovation Project of Chinese Academy of Sciences (Grant Nos. KZCX3-SW-153, KZCX2-YW-116-1), National
Natural Science Foundation of China (Grant No. 40604004), and National Basic Technology R & D Program (Grant No. 2006BAC01B02-01-02). 相似文献
5.
RELOCATION OF MAIN SHOCK AND AFTERSHOCKS OF THE 2014 YINGJIANG MS5.6 AND MS6.1 EARTHQUAKES IN YUNNAN 
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下载免费PDF全文 Yingjiang area is located in the China-Burma border,the Sudian-Xima arc tectonic belt,which lies in the collision zone between the Indian and Eurasian plates.The Yingjiang earthquake occurring on May 30th,2014 is the only event above MS6.0 in this region since seismicity can be recorded.In this study,we relocated the Yingjiang MS5.6 and MS6.1 earthquake sequences by using the double-difference method.The results show that two main shocks are located in the east of the Kachang-Dazhuzhai Fault,the northern segment of the Sudian-Xima Fault.Compared with the Yingjiang MS5.6 earthquake,the Yingjiang MS6.1 earthquake is nearer to the Kachang-Dazhuzhai Fault.The aftershocks of the two earthquakes are distributed along the strike direction of the Kachang-Dazhuzhai Fault (NNE).The rupture zone of the main shock of Yingjiang MS6.1 earthquake extends northward approximately 5km.The aftershocks of two earthquakes are mainly located in the eastern side of the Kachang-Dazhuzhai Fault with a significant asymmetry along the fault,which differ from the characteristics of the aftershock distribution of the strike-slip earthquake.It may indicate that the Yingjiang earthquakes are conjugate rupture earthquakes.The non-double-couple components are relatively high in the moment tensor.We speculate that the Yingjiang earthquakes are related to the fractured zone caused by the long-term seismic activity and heat effect in the deep between Kachang-Dazhuzhai Fault and its neighboring secondary faults.Aftershock distribution of the Yingjiang MS6.1 earthquake on the southern area crosses a secondary fault on the right of the Kachang-Dazhuzhai Fault,suggesting that the coseismic rupture of the secondary fault may be triggered by the dynamic stress of the main shock. 相似文献
6.
汶川8.0级地震序列重新定位及其发震构造初探 总被引：10，自引：1，他引：9
采用双差定位方法对汶川8.0级地震及其2,216次余震进行了重新定位,得到2,061次地震的震源位置,定位结果在水平向和垂直向的估算误差大致为1～2km和2～3km。8.0级主震的震中位置大致为北纬31.00°,东经103.38°,震源深度13km左右,发震构造为龙门山中央断裂。余震震中沿走向分布的总长度为330km左右,震源深度优势分布在3～20km,表现出明显的分段活动特征。南段以龙门山中央断裂活动为主,后山断裂和前山断裂也有地震发生,这3条断裂自西向东倾角似乎逐渐变缓,形成叠瓦状的破裂分布。北段龙门山中央断裂、平武-青川断裂等多条断裂参与了发震过程,地震破裂既有逆冲推覆,也有右旋走滑方式 相似文献
7.
利用此次伽师地震序列震相数据,通过走时曲线得到震源区的初始一维速度模型。结合此速度模型,利用单纯形法测定了新疆伽师M S6.4地震参数。使用双差定位方法对伽师地震和M L≥1.8的297次余震事件进行了重新定位,得到结论:①伽师M S6.4地震参数为39.841°N、77.151°E、深度14.4 km。②伽师地震的破裂是非均匀、迁移的。主、余震整体分布呈“T”字型展布,主震位于“T”字底部,“T”字的横长竖短,多数余震向主震的正北方向延伸,余震整体呈近东西方向展布,东西方向长约40 km,南北方向长约20 km。前震、主震发生在震源区近南面的隐伏断层,可能是受塔里木盆地的阻碍,余震并没有向南发展,而是逐渐向北延伸至位于北面的隐伏断层,后又沿北面的断层向东发展。③通过序列整体分布呈“T”字型展布,初步判断伽师地震是一次共轭断层破裂事件。余震一边向主震正北方向发展,一边继续向东发展,表明发震断层是一条近EW向北倾断层,同时证明了塔里木盆地向北插入南天山。④地震震源深度主要集中在10~20 km,占73%,优势破裂深度在中地壳,中地壳积累和释放的能量居多。伽师地震位于塔里木盆地边缘,地表覆盖有7~8 km的低速沉积层。 相似文献
8.
9.
北京时间2017年11月18日06时34分（GMT：2017-11-17 22∶34）,西藏自治区林芝市米林县发生了M6.9地震.本次地震位于东喜马拉雅东构造结末端旋转变形强烈部位.本研究基于林芝台阵记录的波形数据,应用双差定位方法和匹配滤波方法对本次地震早期余震序列进行了全面检测分析.截至2017年11月25日上午08时,我们共获得约10倍的中国地震台网公布的余震事件.余震的时空分布特征显示,本次米林M6.9地震余震呈NW向,位于北东向南迦巴瓦构造结北部的东西两侧边界断裂带之间,沿西兴拉断裂带分布,断层具有明显的分段破裂特征,主震位于余震分布带中部.根据余震分布特征以及震源机制解显示,发震断层的深部几何结构为北东向陡倾,主震北东侧的断层活动为主震及发震断层触发的结果,其深部几何结构也较陡,余震整体沿断层分布长度约50 km. 相似文献
10.
E. Banda A. Udias St. Mueller J. Mezcua M. Boloix J. Gallart A. Aparicio 《Physics of the Earth and Planetary Interiors》1983,31(4):277-280
Major tectonic units of Spain have been investigated by deep seismic sounding experiments since 1974 to determine crustal structures and to delineate their differences. These areas are the central part of the Hercynian Meseta, and the Alpine chains: the Betic Cordillera in the south, including the Balearic promontory and the Alboran Sea, and the Pyrenees in the north.The main features of the crust and the upper mantle along a NNE-SSW cross-section from the Pyrenees to the Alboran Sea are described.The crust under the Meseta is typical of Hercynian areas found elsewhere in Europe, with an average thickness of 31 km, whereas the two Alpine regions are characterized by very large lateral inhomogeneities, such as rapid thickening of the crust to 50 and 40 km under the Pyrenees and the Betics, respectively. The deep-reaching E-W-trending North Pyrenean fault has a throw of 10–15 km at the base of the crust. A Pn velocity of 8.1 km s?1 is found under the entire Iberian Peninsula.In the Alboran Sea, strongly varying thicknesses of sediments, shallow variable depths to the Moho (～ 13 km under the Alboran ridge), and strong variations of Pn velocity between 7.5 and 8.2 km s?1 have been found. 相似文献
11.
基于新疆区域数字地震台网震相观测报告, 采用双差定位方法对2019年新疆疏附MS5.1地震序列ML≥1.0地震进行重定位, 采用CAP波形反演方法, 获得了主震的震源机制解和震源矩心深度, 进而综合分析了本次地震可能的发震构造。 结果表明, 疏附5.1级地震震源位置为39.59°N, 75.57°E, 初始破裂深度为18 km, 震源矩心深度为18 km。 重定位后的地震序列呈两个优势方向展布, 分别为NEE向和NE向分支, NEE向为主要的余震优势分布区域, 呈长约13 km窄带状分布在喀什断裂附近。 另一条优势分布为沿NE向长度约9 km, 这可能与喀什断裂阶区有关。 深度剖面显示, 地震震源深度主要集中分布在8~20 km。 沿NEE走向深度剖面显示, 疏附5.1级地震破裂于深部, 余震沿优势分布的震源深度自SWW向NEE呈现逐渐加深的变化特征。 垂直于震中优势分布的深度剖面显示, 本次地震发震断层面倾向为N倾。 震源机制解显示本次地震断错类型为逆冲型, 结合震源深度剖面特征推断节面Ⅰ为本次地震的发震断层面。 综合地震序列空间分布特征、 震源机制以及震源区地质资料, 推测此次地震的发震构造可能为喀什断裂, 余震向浅部扩展。 相似文献
12.
13.
The dynamic evolution of the Pyrenees is discussed in the light of geophysical data. Recent deep seismic sounding have revealed the crustal structure of the Pyrenees which is used to test the different evolutionary models proposed until now.The crustal thickness of the Paleozoic Axial Zone (PAZ) and the North Pyrenean Zone (NPZ) differ by more than 10 km, ranging from about 30 km in the NPZ to 40–50 km in the PAZ. The transition from PAZ to the NPZ, identified at the surface as the North Pyrenean Fault (NPF), is sharp at depth and marked by a vertical step, at least in the eastern half of the range. The NPZ is characterized by additional throws and dips of the Moho in the east whereas in the west a heterogeneous middle to lower crust is encountered, with high velocity anomalies. The seismic results suggest that the PAZ and the NPZ belong to different plates, the NPF being the plate boundary. These results are inconsistent with evolutionary models involving lithospheric subduction or crustal doubling and intracratonic rifting with the main tectonic lineations following NNE-SSW directions. They rather suggest that after a period of extension, two main orogenic events took place: a phase involving shearing and thinning which affected mainly the present-day NPZ and a later compressive phase which explains the building up of the chain, the thickening of the crust and the enhancement of a pre-existing difference in crustal thickness between the European and Iberian plates. 相似文献
14.
We relocated M8.0 Wenchuan earthquake and 2706 aftershocks with M⩾2.0 using double-difference algorithm and obtained relocations of 2553 events. To reduce the influence of lateral variation
in crustal and upper mantle velocity structure, we used different velocity models for the east and west side of Longmenshan
fault zone. In the relocation process, we added seismic data from portable seismic stations close to the shocks to constrain
focal depths. The precisions in E-W, N-S, and U-D directions after relocation are 0.6, 0.7, and 2.5 km respectively. The relocation
results show that the aftershock epi-centers of Wenchuan earthquake were distributed in NE-SW direction, with a total length
of about 330 km. The aftershocks were concentrated on the west side of the central fault of Longmenshan fault zone, excluding
those on the north of Qingchuan, which obviously deviated from the surface fault and passed through Pingwu-Qingchuan fault
in the north. The dominant focal depths of the aftershocks are between 5 and 20 km, the average depth is 13.3 km, and the
depth of the relocated main shock is 16.0 km. The depth profile reveals that focal depth distribution in some of the areas
is characterized by high-angle westward dipping. The rupture mode of the main shock features reverse faulting in the south,
with a large strike-slip component in the north.
Supported by the Basic Research Project of Institute of Geophysics, China Earthquake Administration (Grant No. DQJB08Z03) 相似文献
15.
Two temporary seismological networks have been set up in 2000 and 2002 in the central part of the Pyrenees, in a region, which appears as a transition between two domains where both the seismic activity and the tectonic regime are different. Together with the permanent networks, they allowed us to obtain precise hypocenter locations for more than 400 events with local magnitudes ranging from 1.5 to 4.6, as well as 30 new focal mechanisms. The seismicity is distributed in several clusters, which are not located along the North Pyrenean Fault, considered as the major tectonic accident resulting from the suture of the Iberian and Eurasian convergent plates when the range formed. Several small fault segments dipping to the north are identified. The maximum focal depth varies from 10 to 20 km, with variations which are roughly parallel to those of the Moho, indicating a thickening of the seismogenic layer to the east of the studied area. The obtained focal solutions reveal a predominance of normal faulting to the West and reverse faulting to the East, with strike-slip motions in between. The largest fault segment to the East, with a length of about 20 km, could possibly be related to a large historical event which occurred in 1660, with intensity IX, close to cities which have become since then important touristic centres. 相似文献
16.
通过唐山震中的地震测深以及深反射剖面,揭示了唐山震源区的浅部及深部构造图象,它与以往的推测很不相同。 唐山东面的开平向斜属中生代构造,探测的结果表明,向斜轴是一近于直立的地壳断裂。唐山地震时的水平地形变主要是由开平地壳断裂的位移引起的,它是北北东-南南西向右旋走滑断裂。开平地壳断裂西面的陡河断层是一自地表向南东方向下插的正断层,断层倾角为26°,延伸至5km深处。陡河正断层刚好插到唐山市震中区的正下方。唐山地震时的垂直地形变主要是由陡河正断层的滑动引起的。 野鸡坨-丰台断层通过震源区的西部边缘,断层以西的第四纪沉积层,在过去一百万年间曾经沿北北东方向水平滑移15km,表明它也是一个右旋的走滑断层。但是它在近代数百年间并无地震活动,唐山地震时该断层的滑动亦不明显。 开平地壳断裂和陡河正断层在唐山地震时同时滑动,说明地震的作用力除区域水平构造力外,地壳上方还存在一个附加的引张力。在开平断裂处,上部地壳的反射面倾角杂乱,而且在它的正下方,莫霍界面明显错断,因此,地幔顶部的热物质可能自开平地壳断裂中上升。热物质产生的热应力在地壳上方可表现为张应力,而在地壳下方却表现为压应力,这与反射地震剖面图的现象相符合。开平地壳断裂中热物质的上升对地震的产生有 相似文献
17.
J. Gallart M. Daignières J. Gagnepain-Beyneix A. Hirn C. Olivera 《Pure and Applied Geophysics》1984,122(5):713-724
Seismic studies of the last ten years in the Pyrenees (deep seismic profiles, fan profiles at critical distance, teleseismic travel-time residuals, seismicity from temporary networks) and their most significant results concerning crustal thickness in the different structural units of the range, sharpness of the transition between these units at depth, and east-west lateral evolution are reviewed in this paper. Focal mechanisms for three recent earthquakes ofM4 are given, and connections of local seismicity with major tectonic structures such as the North Pyrenean Fault and its western prolongation at depth are described. 相似文献
18.
利用1965——1981年mb4.0的580个地震,研究了中、缅、印交界地区的地震空间分布特征,得到地震主要在阿萨姆块体周围及凹向块体的断裂带上成带或成群分布;在缅甸北部大约由20N到26N存在倾斜地震带,其倾向由南到北逐渐由东转向南东东,其倾角由30变为50;地震带厚度为20——30km;作了38个地震的机制解,机制解表明,在缅甸北部、阿萨姆块体及其相邻地区压力轴为北东方向且近于水平,反映了印度板块以北东方向挤压欧亚板块. 相似文献
19.
On August 8, 2017, Beijing time, an earthquake of M7.0 occurred in Jiuzhaigou County, Aba Prefecture, Sichuan Province, with the epicenter located at 33.20°N 103.82°E. The earthquake caused 25 people dead, 525 people injured, 6 people missing and 170000 people affected. Many houses were damaged to various degrees. Up to October 15, 2017, a total of 7679 aftershocks were recorded, including 2099 earthquakes of M ≥ 1.0.
The M7.0 Jiuzhaigou earthquake occurred in the northeastern boundary belt of the Bayan Har block on the Qinghai-Tibet Plateau, where many active faults are developed, including the Tazhong Fault(the eastern segment of the East Kunlun Fault), the Minjiang fault zone, the Xueshan fault zone, the Huya fault zone, the Wenxian fault zone, the Guanggaishan-Daishan Fault, the Bailongjiang Fault, the Longriuba Fault and the Longmenshan Fault. As one of the important passages for the eastward extrusion movement of the Qinghai-Tibet Plateau(Tapponnier et al., 2001), the East Kunlun fault zone has a crucial influence on the tectonic activities of the northeastern boundary belt of Bayan Kala. Meanwhile, the Coulomb stress, fault strain and other research results show that the eastern boundary of the Bayan Har block still has a high risk of strong earthquakes in the future. So the study of the M7.0 Jiuzhaigou earthquake' seismogenic faults and stress fields is of great significance for scientific understanding of the seismogenic environment and geodynamics of the eastern boundary of Bayan Har block.
In this paper, the epicenter of the main shock and its aftershocks were relocated by the double-difference relocation method and the spatial distribution of the aftershock sequence was obtained. Then we determined the focal mechanism solutions of 24 aftershocks(M ≥ 3.0)by using the CAP algorithm with the waveform records of China Digital Seismic Network. After that, we applied the sliding fitting algorithm to invert the stress field of the earthquake area based on the previous results of the mechanism solutions. Combining with the previous research results of seismogeology in this area, we discussed the seismogenic fault structure and dynamic characteristics of the M7.0 Jiuzhaigou earthquake. Our research results indicated that:1)The epicenters of the M7.0 Jiuzhaigou earthquake sequence distribute along NW-SE in a stripe pattern with a long axis of about 35km and a short axis of about 8km, and with high inclination and dipping to the southwest, the focal depths are mainly concentrated in the range of 2~25km, gradually deepening from northwest to southeast along the fault, but the dip angle does not change remarkably on the whole fault. 2)The focal mechanism solution of the M7.0 Jiuzhaigou earthquake is:strike 151°, dip 69° and rake 12° for nodal plane Ⅰ, and 245°, 78° and -158° for nodal plane Ⅱ, the main shock type is pure strike-slip and the centroid depth of the earthquake is about 5km. Most of the focal mechanism of the aftershock sequence is strike-slip type, which is consistent with the main shock's focal mechanism solution; 3)In the earthquake source area, the principal compressive stress and the principal tensile stress are both near horizontal, and the principal compressive stress is near east-west direction, while the principal tensile stress is near north-south direction. The Jiuzhaigou earthquake is a strike-slip event that occurs under the horizontal compressive stress. 相似文献