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1.
K–Ar ages have been determined for 14 late Miocene to Pliocene volcanic rocks in the north of the Kanto Mountains, Japan, for tracking the location of the volcanic front through the time. These samples were collected from volcanoes located behind the trench–trench–trench (TTT) triple junction of the Pacific, Philippine Sea, and North American plates. This junction is the site of subduction of slabs of the Pacific and the Philippine Sea plates, both of which are thought to have influenced magmatism in this region. The stratigraphy and K–Ar ages of volcanic rocks in the study area indicate that volcanism occurred between the late Miocene and the Pliocene, and ceased before the Pleistocene. Volcanism in adjacent areas of the southern NE Japan and northern Izu–Bonin arcs also occurred during the Pliocene and ceased at around 3 Ma with the westward migration of the volcanic front, as reported previously. Combining our new age data with the existing data shows that before 3 Ma the volcanic front around the TTT junction was located about 50 km east of the preset‐day volcanic front. We suggest that northward subduction of the Philippine Sea Plate slab ended at ～3 Ma as a result of collision between the northern margin of the plate with the surface of the Pacific Plate slab. This collision may have caused a change in the subduction vector of the Philippine Sea Plate from the original north‐directed subduction to the present‐day northwest‐directed subduction. This indicates that the post ～3 Ma westward migration of the volcanic front was a result of this change in plate motion. 相似文献
2.
基于我国台湾地区24个宽频带地震台记录到的长达18个月的三分量连续波形数据,采用交叉项互相关方法提取了瑞雷波的经验格林函数张量,进而反演获得了台湾地区6—22 s周期的瑞雷波相速度分布图像,较好地刻画了该地区的地壳速度结构。结果显示:短周期图像上的滨海平原、屏东平原等呈低速特征,西部丘陵、中央山脉和海岸山脉呈高速特征;低速区域随相速度周期的增大而逐渐东移;中长周期图像上,中央山脉南北部均呈低速且南侧的速度较北侧低,表明欧亚板块和菲律宾海板块碰撞后的物质从东北和西南两个方向被侧向挤出时南部可能较北部活跃;台中—南投地区在对应深度附近的高速异常,表明新生代时期的澎湖地台在南海北缘的拉张与碰撞演化过程中,保留了其相对稳定的性质。 相似文献
3.
Recent crustal movements in eastern Taiwan were investigated based on geodetic and seismological data as a case study of the tectonics along a colliding plate boundary. Secular horizontal strain along the Longitudinal Valley, a probable arc-continent collision boundary between the Philippine Sea and Eurasion plates, is compressive with a large rate of 2 microstrains/year, and the maximum compression axis trends in NW-SE direction. This means that nearly two-thirds of the convergence rate between the two plates is consumed in the narrow zone along the valley and confirms the view that the valley is the plate boundary between the two. The amount of uplift in the Central Range, deduced from trigonometric leveling, reaches more than one meter during the past 60 years. Such active orogeny is caused by the high strain rate in this area. Horizontal displacement of the Coastal Range, a leading edge of the Philippine Sea plate, has a left-lateral component, suggesting that the boundary is a region of oblique collision and the range moves toward the north, producing subduction of the Philippine Sea plate off the Coast of northeastern Taiwan.An extensional strain pattern is found northeastern Taiwan near Hualien, in northern Taiwan near Ilan, and in southeastern Taiwan south Taitung. In northeastern Taiwan, the direction of the maximum extension axis is nearly parallel to the isodipth contours of deep-focus earthquakes that occurred under the southern part of the Ryukyu Trench. From a model calculation using a finite-element method, this pattern of strain is interpreted as an edge effect of the collision-subduction junction in northeastern Taiwan. The direction of the maximum extension in northern Taiwan forms high angles with the direction of the tectonic line near Ilan stretching from the Okinawa Trough. This fact is harmonious with the view that the Okinawa Trough is spreading. Extensional strain observed in southeastern Taiwan may be related to the eastward subduction since the area is situated on a transition zone, from collision to subduction. 相似文献
4.
The origin of strata within the inner accretionary prism of Nankai Trough: Evidence from clay mineral assemblages along the NanTroSEIZE transect 
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下载免费PDF全文 Michael B. Underwood 《Island Arc》2018,27(3)
One of the more prominent architectural elements of the Nankai subduction margin, offshore southwest Japan, is an out‐of‐sequence thrust fault (megasplay) that separates the inner accretionary prism from the outer prism. The inner prism (hanging wall of the megasplay) is dominated by mudstone, which is enigmatic when the sedimentary facies is compared to coeval deposits in the Shikoku Basin (i.e. inputs from the subducting Philippine Sea plate) and to coarser‐grained turbidite sequences from the Quaternary trench wedge. Clay mineral assemblages amplify the mismatches of sedimentary facies. Mudstones from the inner prism are uniformly depleted in smectite, with average bulk values of 23–24 wt%, whereas the Shikoku Basin deposits show progressive decreases in proportions of smectite over time, from averages of 46–48 wt% at 10 Ma to 17–21 wt% at 1 Ma. Plate‐boundary reconstructions for the Philippine Sea region provide one solution to the conundrum. Between 15 Ma and 10 Ma, the Pacific plate subducted near the NanTroSEIZE transect, and a trench‐trench‐trench triple junction migrated to the northeast. Accretion during that period involved sediments that had been deposited on the Pacific plate. Motion of the Philippine Sea plate changed from 10 Ma to 6 Ma, resulting in sinistral slip along the proto‐Nankai Trough. Sediments accreted during that period probably had been deposited near the triple junction, with a hybrid detrital provenance. Renewed subduction of the Philippine Sea plate at 6 Ma led to reorganization of watersheds near the Izu–Honshu collision zone and gradual incision of large submarine canyons on both sides of the colliding Izu arc. Accreted Pliocene mudstones share more of an affinity to the triple junction paleoenvironment than they do to Shikoku Basin. These differences between subducting Shikoku Basin strata and accreted Pacific plate sediments have important implications for interpretations of frictional properties, structural architecture, and diagenetic fluid production. 相似文献
5.
琉球海沟的构造和运动特征 总被引：3，自引：3，他引：3
琉球海沟是欧亚板块与菲律宾海板块之间的边界，海沟西坡是大陆性质的琉球岛弧，东坡是大洋性质的菲律宾海地壳．海底地震反射探测和地震震源定位表明，菲律宾海板块沿海沟向琉球岛弧下俯冲，俯冲角度与深度沿海沟走向变化．有证据显示，由于俯冲板前缘的横向移动，海沟和岛弧正朝大洋方向后退，弧后盆地-冲绳海槽发生拉张变形．最近一次的海沟后退与冲绳海槽扩张可能是从上新世末(2Ma前)开始的，岛弧的后退移动和弧后拉张在南部与海沟走向垂直，在中部和北部与海沟走向斜交，总体上向南的运动分量占优势、与海沟后退相关的弧后拉张集中在冲绳海槽，没有证据表明对其西侧的中国东海陆架盆地产生影响、海沟后退的原因可能与俯冲板的动力不平衡以及它与周围地幔的相互作用有关． 相似文献
6.
台湾是菲律宾海板块与欧亚板块会聚、碰撞的产物,区内地质构造复杂,地震频发,变形强烈.为定量研究台湾地区变形特征及其动力学成因,文中运用二维不连续变形体弹性力学的有限单元计算方法,利用台湾地区1995—2005年GPS的观测结果作为边界约束,对台湾地区地壳变形场进行了模拟.计算结果显示,台湾中部地区主要呈压缩状态,但在台湾的东北部及南部地区出现了拉张的变形环境.变形程度最大的区域位于台湾东部海岸山脉及其附近海域,同时,计算给出台湾纵谷断裂滑移速率约为13.8~23.5mm/yr,由于纵谷断裂对变形的吸收,因此变形在纵谷断裂以西及西北地区迅速衰减.此外,计算结果还发现,计算给出的台湾岛上的速度值与GPS观测结果吻合得较好;计算给出的主应力方位与地应力观测及震源机制解结果也颇为一致.由此说明文中的有限元模型是合理的.此外,计算结果还表明,菲律宾海板块向北西方向的推挤,板块边界形状,观音、北康高地的抵阻,冲绳海槽扩张及琉球海沟的向南后撤以及断裂作用等,共同造成了台湾地区现今变形场的主要格局. 相似文献
7.
通过建立非震形变的位错模型,用混合全局反演方法,拟合了中国台湾南部1990-1995年间的GPS观测资料.根据地质构造和地震观测,构筑了包括6个刚性块体和19个断层的简单模型.反演结果表明,菲律宾海板块以(69±2)mm/a,方向为317°±2°的速度与欧亚板块会聚,其中约一半的会聚率在台东纵谷消耗掉,另外部分则平均分配在其西边的块体交界处.菲律宾海板块和中央山脉地质区均向西北方向挤压,过了中央山脉后,块体运动呈扇形分布,与应力方向一致.西部麓山地质区与滨海平原地质区交界处的断层均以逆冲分量为主,由南向北倾角逐渐变小,断层宽度一般为10km左右,均表现为强锁定,历史上的大地震多发生在这个地区. 相似文献
8.
Late Cenozoic formations in Boso and Miura have been affected by several tectonic events. Tectonic analysis enables us to reconstruct six different paleostress types: (1) early extension affecting the Oligocene/early Miocene Mineoka Group, (2) and (3), relatively minor compressional and extensional events probably early Pliocene in age, (4) major NNE-SSW compression dominating prior to 2 or 3 Ma ago, and (5) and (6) more recent major NNW-SSE compression to the west and WNW-ESE extension to the east, both types affecting the Pleistocene and prevailing since 1–2 Ma ago. The counterclockwise change from NNE-SSW to NNW-SSE compression is not accurately dated, but very likely occurred between 2 and 3 Ma ago; it is compared to similar evolutions in other areas of the Izu collision zone. We conclude that it corresponds to a major counterclockwise change in the direction of plate convergence (from SSE-NNW to SE-NW). The relationships between the directions of convergence and the distributions of Plio-Quaternary compressional paleostresses in and around the collision zone are described through a simple analogy, for the two stages of Plio-Quaternary collision. This counterclockwise change in stress fields and relative motions, also described in the Taiwan collision zone along the same Philippine Sea plate-Eurasia boundary, is interpreted as a major event at the scale of the plate. The possible significances of the other paleostress types identified in Boso are discussed. We conclude that tectonic analysis in and along collision boundaries provides a key for understanding kinematic evolution. 相似文献
9.
Paleomagnetic measurements have been carried out on welded tuffs ranging in age between 58 Ma and 112 Ma from Yamaguchi and Go¯river areas in the central part of Southwest Japan. The new data, together with those of younger igneous rocks published previously, define the change of paleomagnetic field direction during the late Mesozoic/ Cenozoic period for Southwest Japan. The paleomagnetic direction from this area has pointed 56 ± 3° clockwise from the expected field direction estimated from APWP (apparent polar wandering path) of the whole of Eurasia during the period between 100 and 20 Ma. In comparison with the expected one from the eastern margin of Eurasia (Korea, China, Siberia), the Cretaceous field direction of Southwest Japan shows the clockwise deflection by 44–49°. These results establish that while the eastern margin of Eurasia, including Southwest Japan, was rotated more or less with respect to the main part of Eurasia during last 100 Ma, Southwest Japan was rotated clockwise through more than 40° with respect to the eastern margin of Eurasia since 20 Ma. The large amount of rotation for Southwest Japan implies that it is rotated by an opening of the southwestern part of the Japan Sea, which widens northeastward (fan shape opening). The tectonic feature of Southwest Japan and the Japan Sea is analogous to that of Corso-Sardinia and the Ligurian Sea in the Mediterranean, indicating that the fan shape opening is a specific feature of the rifting of the continental sliver at the continental rim. 相似文献
10.
While postulated causes of initial subduction and trench formation include underthrusting, controls on its location and age have not been determined. Consideration of the age of subduction zones bordering five collisional orogens suggests that subduction may have been initiated by foreland thrusts and back-thrusts. Foreland thrusts develop within a continental foreland on the subducting plate mostly within 50 my of collision with an arc system; where the foreland is narrow the thrusts may intersect the continent-ocean crust boundary. Back-thrusts develop in the fore-arc or back-arc area on the overriding plate within 10 to 20 my of collision, and can result in tectonic burial of the magmatic arc; where the arc system is oceanic the back-thrusts may intersect the arc-ocean crust boundary. Possible examples of subduction initiated by foreland thrusts are the start of subduction in the late Jurassic beneath the northern Sunda Arc, and at the end-Miocene in the Negros Trench. Examples of back-thrusts which have initiated or may initiate subduction are the late Cenozoic eastward translation of Taiwan over the Philippine Sea plate, the incipient southward subduction of the Banda Sea beneath Timor, and the W-dipping back-thrust comprising the Highland Boundary Fault zone and postulated early Ordovician thrusts to the SE in Scotland. The suggested relationship of subduction to collision helps to explain the persistence of Wilson cycles in the still-active late Mesozoic to Cenozoic orogenic belts and implies that orogeny will cease only with collision between major continents. 相似文献
11.
自3 Ma至现今,在欧亚东缘太平洋、菲律宾海板块以较大速率朝NWW方向运动,并沿海沟向欧亚大陆俯冲;同时欧亚板块以较小速率朝SEE方向移动,构成双方向的板块汇聚格局.沿日本岛弧东侧,海洋板片以较小的倾角插入欧亚大陆下面,在浅部产生的挤压变形扩展到日本海东边缘.琉球岛弧的中、北部,菲律宾海俯冲板片的倾角较大,其西南段由NE向转变为EW向,正经历活动的海沟后退与弧后扩张.台湾是3种板块汇聚的交点:欧亚沿马尼拉海沟向东俯冲,吕宋弧与台湾碰撞,使台湾岛陆壳东西向缩短与隆升,形成年轻的造山带,菲律宾海板块沿琉球海沟的西南段向北俯冲到欧亚下面.位于南海与菲律宾海之间的菲律宾群岛是宽的变形过渡带,两侧被欧亚向东、菲律宾海向西俯冲夹击,中间是大型左旋走滑断层.总体上,现今时期的太平洋、菲律宾海板块的西向俯冲运动所产生的变形主要分布在俯冲板片内部及岛弧,未扩散到弧后地区,可能这种俯冲运动产生的水平应力较小,不能阻挡欧亚大陆的向东移动,对大陆内部的现今构造没有明显的影响. 相似文献
12.
根据菲律宾海的演化,指出菲律宾海板块的特点:以俯冲边界为主,易于产生形变.将理论结果与地球物理、地质以及GPS测量结果进行比较,发现菲律宾海板块内部及边界有明显形变.讨论了菲律宾海板块与欧亚板块的相互作用,指出其相互作用有明显的分段性.在南海海槽一带有较强的挤压,在琉球海沟一带由于两板块耦合较弱及冲绳海槽的开裂,没有形成对东亚大陆的挤压;台湾附近两板块碰撞,对中国东南形成较强的挤压;在菲律宾群岛一带形成两板块间的复杂变形带,使两板块间的作用减弱. 相似文献
13.
利用中国地震台网和ISC台站1980～2004年的地震数据，反演了南海东北部及其邻近地区的Pn波速度结构和各向异性.上地幔顶部的速度变化揭示出区域地质构造的深部特征：华南地区速度较高并且变化平缓，具有构造稳定地区的岩石层地幔特征；华南沿海尤其是滨海断裂带附近出现低速异常，表明该断裂可能穿过壳幔边界深达上地幔顶部.南海北部至台湾海峡较高的速度与华南地区类似，反映出大陆边缘和陆架地区的岩石层地幔性质；西沙海槽附近较高的速度不仅反映了华南大陆向南的延伸，而且与海槽裂谷拉张引起的地幔上拱有关，整个南海北部没有发现大规模地幔热流的活动痕迹.相比之下，南海东部次海盆的上地幔顶部存在明显的低速异常，对应于海底扩张中心的地幔上涌区，表明岩石层地幔强烈减薄甚至缺失；台湾东部－吕宋－菲律宾北部的低速异常与地震、火山活动以及岩浆作用紧密相关，揭示了西太平洋岛弧俯冲带的活动特征；南海东北部的洋－陆边界清晰，南海东部和菲律宾海西部较高的速度代表了海洋岩石层地幔的性质.Pn波各向异性反映出区域性构造应力状态及岩石层地幔的变形痕迹：华南地区的各向异性较小，说明这一构造稳定地区的岩石层地幔变形程度较弱；南海北部的快波方向与地壳浅表层构造的伸展方向一致，主要反映了中、新生代以来的大陆边缘张裂和剪切作用对岩石层地幔结构的影响；琉球－台湾－吕宋岛弧两侧各向异性十分强烈，平行于海沟的快波方向表明菲律宾海板块和欧亚大陆的相互作用导致俯冲板块前缘的岩石层地幔强烈变形；台湾东南海域快波方向的变化可能与欧亚大陆和菲律宾海板块俯冲机制的转换以及岩石层被撕裂有关. 相似文献
14.
Abstract The northern tip of the Izu-Ogasawara Arc on the Philippine Sea plate collided with the central part of the Honshu Arc in the early Quaternary. The collision history is recorded in late Cenozoic strata that are distributed widely in central Japan. To reconstruct paleotopography during the collision process, paleogeographic maps of central Japan were drawn at six time slices during the late Cenozoic. These maps were made from paleodepth data that were inferred from benthic foraminiferal fossil assemblages. Sedimentological information was also added to the maps. The paleogeographic maps show several distinctive geological features. The paleodepth of the area between the Izu-Ogasawara Arc and the Honshu Arc changed quickly from deep-sea to shallow marine during the Quaternary by means of rapid deposition of large amounts of coarse-grained detritus. The conglomerate was first deposited in a trough as deep-sea fan deposits, and filled the trough until an alluvial fan was formed. Forearc basins of the Honshu Arc facing the collision area subsided from 3 to 1 Ma. Vertical movement of the basin was inferred from a strata thickness/paleodepth correlation graph. It is thought that the tectonic inversion seen in sedimentary basins in the Kanto and Tokai regions might be closely related to the change of motion of the Philippine Sea plate. However, a basin of the Ashigara area sunk continuously without interruption until 0.7 Ma. The collision event affected strongly distribution of deep-sea benthic foraminifera. Paleogeographic maps show that a deep trough appeared in the Ashigara area between 3 and 1.5 Ma. This trough may have served as a passage for the migration of deep-sea benthic foraminifera between the Pacific and the Philippine Sea. Cold water benthic foraminiferal species occur west of the Izu-Ogasawara ridge deposited in strata during the existence of the passage. 相似文献
15.
《Earth and Planetary Science Letters》2005,229(3-4):259-271
High-resolution reconstruction of Benioff zone depth–dip angle trajectory for Burma–Java subduction margin between 2° and 17°N Lat. reveals two major episodes of plate geometry change expressed as abrupt deviation in subduction angle. Estimation of effective rate of subduction in different time slices (and then length of subducted slab) allowed drawing of isochrones in Ma interval through these trajectories for the time period 5–12 Ma. With these isochrones, the deformation events on the subducting Indian plate are constrained in time as of 4–5 and 11 Ma old. This well-constrained time connotation offered scope for the correlation of slab deformation events with the well-established two-phase opening history of the Andaman Sea. While the 11 Ma event recorded from southern part of the study area is correlated with early stretching and rifting phase, the 4–5 Ma event is interpreted as major forcing behind the spreading phase of the Andaman Sea. Systematic spatio-temporal evaluation of Indian plate obliquity on the Andaman Sea evolution shows its definite control on the early rifting phase, initiated towards south near northwest Sumatra. The much young spreading phase recorded towards north of 7° Lat. is possibly the result of late Miocene–Pliocene trench retreat and follow-up transcurrent movement (along Sagaing and Sumatran fault system) with NW–SE pull-apart extension.Nonconformity between plate shape and subduction margin geometry is interpreted as the causative force behind Mid-Miocene intraplate extension and tearing. Enhanced stretching in the overriding plate consequently caused active forearc subsidence, recorded all along this plate margin. Initial phase of the Andaman Sea opening presumably remains concealed in this early–middle Miocene forearc subsidence history. The late Miocene–Pliocene pull-apart opening and spreading was possibly initiated near the western part of the Mergui–Sumatra region and propagated northward in subsequent period. A temporary halt in rifting at this pull-apart stage and northeastward veering of the Andaman Sea Ridge (ASR) are related with uplifting of oceanic crust in post-middle Miocene time in form of Alcock and Sewell seamounts, lying symmetrically north and south of this spreading ridge. 相似文献
16.
D. Jongsma J.M. Woodside G.C.P. King J.E. van Hinte 《Earth and Planetary Science Letters》1987,82(1-2)
The Medina Wrenth in the central Mediterranean is a transform fault connecting the plate collision in northwest Africa and northern Sicily with that occurring at the Aegean plate boundary, south of Greece. The more than 800 km long crescent-shaped wrench zone is currently seismically quiet but exhibits major deformation since 5 Ma within a belt 30–100 km wide. It forms the southern boundary of two microplates moving eastward with respect to Africa and Europe. A simple plate rotation model constrained by recent paleomagnetic data indicates that a continental Iblean microplate and a hybrid continental/oceanic Ionian microplate, separated along the Malta Escarpment, have rotated anticlockwise by 11° and 12°, respectively, around poles in southern Italy. These rotations involved some 100 km of dextral eastward movement relative to Africa of the Ionian Basin north of the Medina Wrench since 5 Ma. Combining the published 26° clockwise rotation of the Peloponnesus and northwest half of the Aegean with the 12° anticlockwise rotation of the Ionian microplate results in (a) a 99% agreement between the length of the seismic Benioff Zone beneath Greece and the total convergence of the microplates, and (b) an average rate of convergence across the Aegean plate boundary southwest of the Peloponnesus of 6.6 ± 1cm a−1 since the Miocene. Relative motion between microplates in a collision zone thus may be as much as 6 times faster than convergence between the major plates which spawned them, and they can be considered rigid to the first order over the time span involved. 相似文献
17.
Gaku Kimura Yasuyuki Nakamura Kazuya Shiraishi Gou Fujie Shuichi Kodaira Asuka Yamaguchi Rina Fukuchi Yoshitaka Hashimoto 《Island Arc》2021,30(1):e12402
The Nankai Trough, Japan, is a subduction zone characterized by the recurrence of disastrous earthquakes and tsunamis. Slow earthquakes and associated tremor also occur intermittently and locally in the Nankai Trough and the causal relationship between slow earthquakes and large earthquakes is important to understanding subduction zone dynamics. The Nankai Trough off Muroto, Shikoku Island, near the southeast margin of the rupture segment of the 1946 Nankai earthquake, is one of three regions where slow earthquakes and tremor cluster in the Nankai Trough. On the Philippine Sea plate, the rifting of the central domain of the Shikoku Basin was aborted at ~15 Ma and underthrust the Nankai forearc off Muroto. Here, the Tosa-Bae seamount and other high-relief features, which are northern extension of the Kinan Seamount chain, have collided with and indented the forearc wedge. In this study, we analyzed seismic reflection profiles around the deformation front of accretionary wedge and stratigraphically correlated them to drilling sites off Muroto. Our results show that the previously aborted horst-and-graben structures, which were formed around the spreading center of the Shikoku Basin at ~15 Ma, were rejuvenated locally at ~6 Ma and more regionally at ~3.3 Ma and have remained active since. The reactivated normal faulting has enhanced seafloor roughness and appears to affect the locations of slow earthquakes and tremors. Rejuvenated normal faulting is not limited to areas near the Nankai Trough, and extends more than 200 km into the Shikoku Basin to the south. This extension might be due to extensional forces applied to the Philippine Sea plate, which appear to be driven by slab-pull in the Ryukyu and Philippine trenches along the western margin of the Philippine Sea plate. 相似文献
18.
Guy Pautot Kazuaki Nakamura Philippe Huchon Jacques Angelier Jacques Bourgois Kantaro Fujioka Toshihiko Kanazawa Yasuo Nakamura Yujiro Ogawa Michel Sguret Akira Takeuchi 《Earth and Planetary Science Letters》1987,83(1-4)
Nine submersible dives were made in three trenches off central Japan, between 2990 and 5900 m of water depth. Our observations confirm the interpretation that Daiichi-Kashima Seamount is a Cretaceous guyot formed on the Pacific plate that has traveled into the Japan Trench. We also confirmed the previous interpretation of a large normal fault that splits the seamount in two halves, the lower one being now subducting beneath the Japan margin. Compressional deformation was identified within the lower part of the inner slope in front of the seamount. The pattern of deformation that affects Quaternary sediments is in agreement with the present kinematics of the convergence between the Pacific plate and Japan. Deep-water (5700 m) clam colonies are associated with advection of fluids, driven by the subduction-related overpressures. In the northern slope of the Boso Canyon, along the Sagami Trough system (Philippine Sea plate-Japan boundary), the deformation affecting a thick upper Miocene to lower Pliocene sequence indicates two directions of shortening: a N175°E direction which is consistent with the present relative motion along the Sagami Trough (N285–N300°E) and a N30°E direction which could be related to a more northerly direction of convergence that occured during the early Quaternary and earlier. 相似文献
19.
A present-day tectonic stress map for eastern Asia region 总被引：15，自引：1，他引：15
许忠淮 《地震学报(英文版)》2001,14(5):524-533
Introduction Tectonically the eastern Asia refers to the region bounded by the following three active tec-tonic zones: in the east the western Pacific subduction zone, including Japan trench, Ryukyu trench and Philippine trench; in the southwest the Himalaya continental collision zone and the Burma-arc-Java-trench subduction zone; in the northwest the Tianshan-Baikal continental defor-mation zone (Figure 6). In the world the eastern Asia is one of the regions with the strongest pre-sent-da… 相似文献
20.
2006年12月26日12点26分27秒(GMT)台湾南部滨海发生Ms7.2(Harvard CMT)级地震.震中位于台湾南部滨海之南海次板块与菲律宾海板块碰撞引发造山作用生成的海洋增生楔内, 这次地震是该区域百年来震级最大的地震.我们利用中国数字地震台网(CSDN)和美国地震学联合研究所(IRIS) 提供的上地幔及远场范围宽频带P波垂向记录资料,基于点源和有限断层模型进行波形拟合反演,获得这次地震的震源机制解并给出了震源破裂过程.反演结果表明,本次地震为东倾正断层兼小幅度走滑破裂事件, 断层面走向为341.5°,倾角为77.9°,震源深度6 km.所得正断层震源机制解表明,地震可能与板块的拆离（break-off）作用引发的在台湾造山带局部存在伸张作用力有关. 相似文献