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1.
《Gondwana Research》2010,17(3-4):512-526
The spatial distribution of deep slow earthquake activity along the strike of the subducting Philippine Sea Plate in southwest Japan is investigated. These events usually occur simultaneously between the megathrust seismogenic zone and the deeper free-slip zone on the plate interface at depths of about 30 km. Deep low-frequency tremors are weak prolonged vibrations with dominant frequencies of 1.5–5 Hz, whereas low-frequency earthquakes correspond to isolated pulses included within the tremors. Deep very-low-frequency earthquakes have long-period (20 s) seismic signals, and short-term slow-slip events are crustal deformations lasting for several days. Slow earthquake activity is not spatially homogeneous but is separated into segments some of which are bounded by gaps in activity. The spatial distribution of each phase of slow earthquake activity is usually coincident, although there are some inconsistencies. Very-low-frequency earthquakes occur mainly at edges of segments. Low-frequency earthquakes corresponding to tremors of relatively large amplitude are concentrated at spots where tremors are densely distributed within segments. The separation of segments by gaps suggests large differences in stick-slip and stable sliding caused by frictional properties of the plate interface. Within each segment, variations in the spatial distribution of slow earthquakes reflected inhomogeneities corresponding to the characteristic scales of events. 相似文献
2.
The spatial distribution of deep slow earthquake activity along the strike of the subducting Philippine Sea Plate in southwest Japan is investigated. These events usually occur simultaneously between the megathrust seismogenic zone and the deeper free-slip zone on the plate interface at depths of about 30 km. Deep low-frequency tremors are weak prolonged vibrations with dominant frequencies of 1.5–5 Hz, whereas low-frequency earthquakes correspond to isolated pulses included within the tremors. Deep very-low-frequency earthquakes have long-period (20 s) seismic signals, and short-term slow-slip events are crustal deformations lasting for several days. Slow earthquake activity is not spatially homogeneous but is separated into segments some of which are bounded by gaps in activity. The spatial distribution of each phase of slow earthquake activity is usually coincident, although there are some inconsistencies. Very-low-frequency earthquakes occur mainly at edges of segments. Low-frequency earthquakes corresponding to tremors of relatively large amplitude are concentrated at spots where tremors are densely distributed within segments. The separation of segments by gaps suggests large differences in stick-slip and stable sliding caused by frictional properties of the plate interface. Within each segment, variations in the spatial distribution of slow earthquakes reflected inhomogeneities corresponding to the characteristic scales of events. 相似文献
3.
Influence of interaction between small asperities on various types of slow earthquakes in a 3-D simulation for a subduction plate boundary 总被引：3，自引：1，他引：2
Keisuke Ariyoshi Takane Hori Jean-Paul Ampuero Yoshiyuki Kaneda Toru Matsuzawa Ryota Hino Akira Hasegawa 《Gondwana Research》2009,16(3-4):534-544
Recently, the occurrence of slow earthquakes such as low-frequency earthquakes and very low-frequency earthquakes have been recognized at depths of about 30 km in southwest Japan and Cascadia. These slow earthquakes occur sometimes in isolation and sometimes break into chain-reaction, producing tremor that migrates at a speed of about 5–15 km/day and suggesting a strong interaction among nearby small asperities. In this study, we formulate a 3-D subduction plate boundary model with two types of small asperities chained along the trench at the depth of 30 km. Our simulation succeeds in representing various types of slow earthquakes including low-frequency earthquakes and rapid slip velocity in the same asperity, and indicates that interaction between asperities may cause the very low-frequency earthquakes. Our simulation also shows chain reaction along trench with propagation speed that can be made consistent with observations by adjusting model parameters, which suggests that the interactions also explain the observed migration of slow earthquakes. 相似文献
4.
《Gondwana Research》2010,17(3-4):534-544
Recently, the occurrence of slow earthquakes such as low-frequency earthquakes and very low-frequency earthquakes have been recognized at depths of about 30 km in southwest Japan and Cascadia. These slow earthquakes occur sometimes in isolation and sometimes break into chain-reaction, producing tremor that migrates at a speed of about 5–15 km/day and suggesting a strong interaction among nearby small asperities. In this study, we formulate a 3-D subduction plate boundary model with two types of small asperities chained along the trench at the depth of 30 km. Our simulation succeeds in representing various types of slow earthquakes including low-frequency earthquakes and rapid slip velocity in the same asperity, and indicates that interaction between asperities may cause the very low-frequency earthquakes. Our simulation also shows chain reaction along trench with propagation speed that can be made consistent with observations by adjusting model parameters, which suggests that the interactions also explain the observed migration of slow earthquakes. 相似文献
5.
渤海湾盆地是一个在早白垩世被动裂陷盆地基础上发育起来的新生代主动裂陷盆地, 走滑作用贯穿始终, 特别是在兰聊-盐山断层以东, 使这个裂陷盆地具有鲜明的走滑特征。伸展和走滑作用此消彼长, 伸展构造和走滑构造相互叠加、转换, 垂向上相互叠置、交切, 并由此导致变换带的产生。晚中生代以来太平洋板块向欧亚板块俯冲的方向和速度变化、后撤以及板片窗效应、中始新世印欧板块碰撞导致的地幔上涌是控制盆地形成的深部背景, 郯庐断裂带早白垩世强烈的左行走滑、古新世-早始新世弱的左行走滑以及中始新世后的右行走滑活动也深刻地控制和影响着盆地的发育, 盆地内晚中生代-新生代的伸展和走滑构造的演化则是其浅部响应, 并由此控制着岩浆活动以及油气生成、运聚和分布的时空迁移。 相似文献
6.
Three-dimensional P- and S-wave velocity structures beneath the Japan Islands obtained by high-density seismic stations by seismic tomography 总被引：1，自引：0，他引：1
We construct fine-scale 3D P- and S-wave velocity structures of the crust and upper mantle beneath the whole Japan Islands with a unified resolution, where the Pacific (PAC) and Philippine Sea (PHS) plates subduct beneath the Eurasian (EUR) plate. We can detect the low-velocity (low-V) oceanic crust of the PAC and PHS plates at their uppermost part beneath almost all the Japan Islands. The depth limit of the imaged oceanic crust varies with the regions. High-VP/VS zones are widely distributed in the lower crust especially beneath the volcanic front, and the high strain rate zones are located at the edge of the extremely high-VP/VS zone; however, VP/VS at the top of the mantle wedge is not so high. Beneath northern Japan, we can image the high-V subducting PAC plate using the tomographic method without any assumption of velocity discontinuities. We also imaged the heterogeneous structure in the PAC plate, such as the low-V zone considered as the old seamount or the highly seismic zone within the double seismic zone where the seismic fault ruptured by the earthquake connects the upper and lower layer of the double seismic zone. Beneath central Japan, thrust-type small repeating earthquakes occur at the boundary between the EUR and PHS plates and are located at the upper part of the low-V layer that is considered to be the oceanic crust of the PHS plate. In addition to the low-V oceanic crust, the subducting high-V PAC plate is clearly imaged to depths of approximately 250 km and the subducting high-V PHS zone to depths of approximately 180 km is considered to be the PHS plate. Beneath southwestern Japan, the iso-depth lines of the Moho discontinuity in the PHS plate derived by the receiver function method divide the upper low-V layer and lower high-V layer of our model at depths of 30–50 km. Beneath Kyushu, the steeply subducting PHS plate is clearly imaged to depths of approximately 250 km with high velocities. The high-VP/VS zone is considered as the lower crust of the EUR plate or the oceanic crust of the PHS plate at depths of 25–35 km and the partially serpentinized mantle wedge of the EUR plate at depths of 30–45 km beneath southwestern Japan. The deep low-frequency nonvolcanic tremors occur at all parts of the high-VP/VS zone—within the zone, the seaward side, and the landward side where the PHS plate encounters the mantle wedge of the EUR plate. We prove that we can objectively obtain the fine-scale 3D structure with simple constraints such as only 1D initial velocity model with no velocity discontinuity. 相似文献
7.
THREE-DIMENSIONAL DEFORMATION ALONG THE ALTYN TAGH FAULT ZONE AND UPLIFT OF THE ALTYN MOUNTAIN, NORTHERN TIBET 相似文献
8.
基于1992—2002年小震双差重新定位结果,沿鲜水河—安宁河—则木河断裂带走向的震源剖面作b值及局部复发时间TL值的空间扫描,以确定断裂带上可能存在的凹凸体。结果显示,b值沿断裂带走向具明显的空间非均匀性,与地表几何结构的分段变异是相应的。异常短的TL值及低b值出现在鲜水河断裂带的炉霍—道孚间、安宁河断裂带的石棉—冕宁段以及则木河断裂带的西昌—普格段,表明在间震期这些段落破裂产生的小震平均震级大于其他段落上的小震,是断裂带中相对活跃的段落。由b值与应力成反比的关系,推测这些段落可能为断裂带上凹凸体所在地,成为现今应力积累的闭锁段,是未来主震初始破裂最有可能形成的段落,其中石棉—冕宁段的地震危险性最大。而在鲜水河断裂带南东段的乾宁—康定—石棉一带,尽管历史地震与现今小震都异常活跃,但具有异常高的b值及TL值估计,表明现今应力水平较低,目前可能成为以小震活动为主的蠕滑段,不具大震危险性。 相似文献
9.
Reliable fault plane solutions of shallow earthquakes and information on surface fault traces in combination with other seismic, geomorphological and geological information have been used to determine the orientation and other properties of the seismic faults in the Aegean and surrounding area.Thrust faults having an about NW-SE strike occur in the outer seismic zone along western Albania-westernmost part of mainland of Greece-Ionian Sea-south of Crete-south of Rhodes.The inner part of the area is dominated by strike-slip and normal faulting. Strike-slip with an about NE-SW slip direction occurs in the inner part of the Hellenic arc along the line Peloponnesus-Cyclades-Dodecanese-southwest Turkey as well as along a zone which is associated with the northern Aegean trough and the northwesternmost part of Anatolia. All other regions in the inner part of the area are characterized by normal faulting. The slip direction of the normal faults has an about SW-NE direction in Crete (N38°E) and an about E-W direction (N81°E) in a zone which trends N-S in eastern Albania and its extension to western mainland of Greece. In all other regions (central Greece-southern Yugoslavia and Bulgaria, western Turkey) the slip of the normal faults has an about N-S direction. 相似文献
10.
Analysis of vertical crustal deformation data in the southwestern part of Shikoku, southwest Japan, suggests that the Nankaido earthquake of 1946 (Mw = 8.1), which is a principal interplate thrust earthquake, was accompanied by subsidiary faulting on a splay fault adjacent to the coast of Shikoku. Discarding crustal movement resulting from the main thrusting of the Nankaido earthquake, local leveling data are explained by slip on a simple rectangular thrust fault located just offshore of Shikoku. Although it is difficult to constrain the fault location, a possible result is a high-angle thrust dipping landward at an angle of about 70°, with a dislocation of about 1.5 m, and source dimensions of 30 × 13 km along strike and dip. respectively. This result indicates that the fault may be one of the steeply dipping subsidiary faults branching from the main low-angle thrust, as was the case in the Alaska earthquake of 1964. Although several lines of evidence suggest that this faulting occurred as slow aseismic slip, its discrimination from the main seismic event is extremely difficult. This kind of high-angle thrusting just offshore of the coast would play an important role for the formation of the marine terraces during the late Quaternary period. 相似文献
11.
西天山造山带的构造变形特征研究 总被引：7，自引：1，他引：7
西天山造山带由伊犁中天山北缘－北天山推覆走滑系统、伊犁中天山南缘－南天山推覆走滑系统和两者之间的伊犁地块组成。伊犁中天山北缘－北天山推覆走滑系统包括北天山推覆构造带、伊犁中天山北缘逆冲带和中天山北缘断裂带。伊犁中天山南缘－南天山推覆系统包括中天山南缘逆冲带、南天山北坡增生楔推覆席、南天山北坡早古生代被动陆缘推覆席、南天山南坡晚古生代洋壳－火山弧－复理石复合推覆席、中天山南缘断裂带和南天山南坡断裂带。区域构造和变形构造的研究表明西天山推覆构造主要奠定于早二叠世早期，走滑运动发生于晚二叠世－早三叠世。中新生代，沿古生代构造有进一步的推覆和走滑运动发生 相似文献
12.
走滑断裂在渤海海域广泛分布,深刻影响着沉积盆地的形成与演化,同时也深刻影响着源－汇体系的形成和演化.在对渤海海域大量钻井资料和地震资料分析的基础上,认为走滑断裂对渤海古近系源－汇体系的控制作用主要表现在:走滑断裂压扭作用控制了局部物源体系的形成;走滑断裂的张扭作用控制了沟谷低地的形成;走滑断裂的水平运动控制源－汇体系的横向迁移.走滑断裂带源－汇体系发育模式十分复杂,渤海古近系常见的主要有S型走滑断裂带源－汇体系模式、叠覆型走滑断裂带源－汇体系模式、帚状走滑断裂带源－汇体系模式、共轭走滑带源－汇体系模式.开展走滑断裂带源－汇体系特征及其控砂模式的探讨,对含油气盆地的储层预测具有重要的意义. 相似文献
13.
西南三江构造体系突出表现为以昌都-兰坪-思茅地块为中轴的不对称走滑对冲构造,次为与走滑断裂相伴的伸展滑脱、走滑拉分盆地构造体系,再次为块体内部的近北东、北西向走滑断裂系。西南三江造山带构造体系演化分为挤压收缩变形、走滑深熔热隆、走滑剪切伸展、走滑剥蚀隆升等4个阶段。自晚白垩世开始,印度板块与欧亚板块碰撞,西南三江造山带对冲体构造体系初始形成。自渐新世开始,印度板块持续向北楔入欧亚大陆,印度板块与扬子克拉通构成力偶,两者相向、相对运动,挤压与剪切特提斯大洋缝合带及两大陆边缘弧盆系等地质体,西南三江造山带对冲体构造体系进一步发展,近南北向剪切走滑构造体系形成,构造方向也由近东西转为近南北向。而与近南北向主走滑断裂带之相伴的伸展滑脱构造、拉分盆地,块体内部近北东、北西“X”型剪切走滑断裂同时相伴形成。这样,就形成了西南三江造山带大规模的对冲、走滑、旋转及其伴生的伸展、拉分盆地构造的构造体系。 相似文献
14.
《International Geology Review》2012,54(3):302-312
Porphyry Cu (Mo–Au) deposits in the Himalayan–Tibetan orogen formed during the Late Triassic, Early Cretaceous, Eocene, Oligocene, and Miocene and can be classified into different metallogenic belts according to their petrologic features, mineralization ages, and tectonic settings. A close spatial relationship to regional strike–slip faults is evident in all five belts. Porphyry Cu (Mo–Au) deposits exist in a wide range of tectonic environments, including island arc, syn-collision, post-collisional convergence, and continental-transform plate boundaries. Porphyry Cu deposits cluster in the southernmost part of the Yidun–Zhongdian Belt, along the N–S-trending Gaze River dextral strike–slip fault. Porphyry Cu deposits in the Lijiang–Jinping Belt lie along the Ailaoshan–Red River continental–transform shear zone and the associated strike–slip faults. The Yulong–Malasongduo porphyry belt is controlled by the Cesuo Fault, a NNW-trending regional dextral transcurrent fault that is associated with Palaeogene westward continental oblique subduction along the Jinsha suture. In the Gangdis Belt, Miocene porphyry Cu deposits are localized along N–S-trending normal faults, which were produced by transpression within the regional NW–SE-trending Karakoram–Jiali fault zone (KJFZ). A close spatial relationship between porphyry Cu deposits and strike–slip faults also exists for the Bangong–Nujiang Belt. 相似文献
15.
Field-based structural analysis of an exhumed, 10-km-long strike-slip fault zone elucidates processes of growth, linkage, and termination along moderately sized strike-slip fault zones in granitic rocks. The Gemini fault zone is a 9.3-km-long, left-lateral fault system that was active at depths of 8–11 km within the transpressive Late-Cretaceous Sierran magmatic arc. The fault zone cuts four granitic plutons and is composed of three steeply dipping northeast- and southwest-striking noncoplanar segments that nucleated and grew along preexisting cooling joints. The fault core is bounded by subparallel fault planes that separate highly fractured epidote-, chlorite-, and quartz-breccias from undeformed protolith. The slip profile along the Gemini fault zone shows that the fault zone consists of three 2–3-km-long segments separated by two ‘zones’ of local slip minima. Slip is highest (131 m) on the western third of the fault zone and tapers to zero at the eastern termination. Slip vectors plunge shallowly west-southwest and show significant variability along strike and across segment boundaries. Four types of microstructures reflect compositional changes in protolith along strike and show that deformation was concentrated on narrow slip surfaces at, or below, greenschist facies conditions. Taken together, we interpret the fault zone to be a segmented, linked fault zone in which geometrical complexities of the faults and compositional variations of protolith and fault rock resulted in nonuniform slip orientations, complex fault-segment interactions, and asymmetric slip-distance profiles. 相似文献
16.
JIAO Liqing CHAN Chung-Han Luc SCHOLTES Aurelia HUBERT-FERRARI Frederic-Victor DONZE Paul TAPPONNIER 《《地质学报》英文版》2022,96(3):776-790
Seafloor irregularities influence rupture behavior along the subducting slab and in the overriding plate, thus affecting earthquake cycles. Whether seafloor irregularities increase the likelihood of large earthquakes in a subduction zone remains contested, partially due to focus put either on fault development or on rupture pattern. Here, we simulate a subducting slab with a seafloor irregularity and the resulting deformation pattern of the overriding plate using the discrete element method. Our simulations illustrate the rupture along three major fault systems: megathrust, splay and backthrust faults. Our results show different rupture dimensions of earthquake events varying from tens to ca. 140 km. Our results suggest that the recurrence interval of megathrust events with rupture length of ca. 100 km is ca. 140 years, which is overall comparable to the paleoseismic records at the Mentawai area of the Sumatran zone. We further propose the coseismic slip amounts decrease and interseismic slip amounts increase from the surface downwards gradually. 相似文献
17.
18.
Dilip Saha S. Chakraborti V. Tripathy 《Journal of the Geological Society of India》2010,75(1):323-337
Recent works suggest Proterozoic plate convergence along the southeastern margin of India which led to amalgamation of the
high grade Eastern Ghats belt (EGB) and adjoining fold-and-thrust belts to the East Dhrawar craton. Two major thrusts namely
the Vellikonda thrust at the western margin of the Nellore Schist belt (NSB) and the Maidukuru thrust at the western margin
of the Nallamalai fold belt (NFB) accommodate significant upper crustal shortening, which is indicated by juxtaposition of
geological terranes with distinct tectonostratigraphy, varying deformation intensity, structural styles and metamorphic grade.
Kinematic analysis of structures and fabric of the fault zone rocks in these intracontinental thrust zones and the hanging
wall and footwall rocks suggest spatially heterogeneous partitioning of strain into various combinations of E-W shortening,
top-to-west shear on stratum parallel subhorizontal detachments or on easterly dipping thrusts, and a strike slip component.
Although relatively less prominent than the other two components of the strain triangle, non-orthogonal slickenfibres associated with flexural slip folds and mylonitic foliation-stretching lineation orientation
geometry within the arcuate NSB and NFB indicate left lateral strike slip subparallel to the overall N-S trend. On the whole
an inclined transpression is inferred to have controlled the spatially heterogeneous development of thrust related fabric
in the terrane between the Eastern Ghats belt south of the Godavari graben and the East Dharwar craton. 相似文献
19.
XU Jiren ZHAO Zhixin Institute of Geology Chinese Academy of Geological Science Beijing China Kono Yoshiteru Faculty of Science Kanazawa University Kanazawa - Japan 《Continental Dynamics》2000,(1)
1. IntroductionThe Nankai Trough region (Fig. 1.1) of southwest Japan is one of the most tectonically complex subduction zones in the world. The subduction of the Philippine Sea plate (PH) beneath the Eurasian plate (EU) has caused a series of large and great interplate earthquakes. It is generally accepted that great earthquakes have occurred at intervals of 100-150 years along the Nankai subduction zone since the 684 Hakuho earthquake (Fig. 1.2). However, a large earthquake (M>7.5) has… 相似文献
20.
Guang-an Zhu Lin-ming Dou Chang-bin Wang Jing Li Wu Cai Zi-wei Ding 《Arabian Journal of Geosciences》2017,10(24):549
A systematic approach to numerically simulating an island longwall panel operation is proposed: it aims to investigate the evolution of overlying strata, static stress and displacement response and dynamic load arising from roof fracturing and fault slip. The results show that due to a small gob width (70 m) on both sides, the evolution height of overlying strata is limited, i.e. the heights of the cave-in zone and fracture zone are 30.98 and 66.91 m, respectively. The numerical model matches the theoretical analysis and field observations. Dynamic analysis reveals that the envelope of mine tremors confirms the good correlation with the evolution of the fracture zone. As the mining panel is far from the fault, fault slip does not occur; at this time, the dynamic load mainly comes from roof fracturing. When mining activities approach the fault, the calculation of the dynamic response of fault slip is performed over the area where the increase of relative shear displacement during dynamic analysis exceeds 0.05 m and where the shear stress along the fault decreases. It is shown that during the initial stage of the mining process, and in a square mining panel, fault slip is more likely to occur, leading to strong tremors and rock bursts, which become more notable in the later stages of the mining of the island panel. 相似文献