Correlation between movement of tectonicblocks and earthquakes in groups

The Chinese mainland is divided into some tectonic blocks by nearly NE- and EW-orientated faults. Meanwhile strong earthquakes in the Chinese mainland usually cluster in time and space. We call earthquakes in groups. Tectonic blocks separated by faults and earthquakes in groups are prominent features of the tectonics of the Chi-nese mainland. Correlation between movement of tectonic blocks and groups of earthquakes is discussed in this paper. The results show that earthquakes in groups often occurred at one or several block boundary faults. The released elastic strain energy is built up in the same periods and around blocks. It means that strong earthquakes in groups are mainly caused by movement of blocks. Four types of block movement are identified based ongroup earthquakes: movement along a single boundary of a block (or a combined blocks), movement of a single block, movement of multi-blocks, and movement in block interiors. If we consider distribution of all strong earthquakes occurred in the Chinese mainland, the movement along a single boundary of a block is more popular one inducing strong earthquakes. But if we only consider earthquakes in groups rather than single earthquakesthe movement of a block dominates among four modes. Statistics with respect to group earthquakes show that the Taihangshan mountain and the North China block are much active in the eastern part of Chinese mainland, and in western part of Chinese mainland the active blocks are Sichuan-Yunnan and the Kunlun-Songpan ones.

Tectonic Taphrogenesis and Paleoseismic Records from the Yishu Fault Zone in the Initial Stage of the Caledonian Movement

The Yishu fault zone （mid-segment of the Tanlu fault zone） was formed in the Presinian. Periodic tectonic activities and strong seismic events have occurred along the fault zone. During the initial stage of the Caledonian Movement, with the proceeding of the marine transgression from the Yishu paleo-channel to the western Shandong, uneven thick sediments, composed mainly of sand, mud and carbonates of littoral, lagoon, and neritic facies, were deposited in the Yishu fault zone and western Shandong, and constructed the bottom part of the Lower Cambrian consisting of the Liguan and Zhushadong formations. Through field observations and the lab-examinations, various paleoseismic records have been discovered in the Liguan Formation and the Zhushadong Formations of the Yishu fault zone and its vicinity, including some layers with syn-sedimentary deformation structures that were triggered by strong earthquakes （i.e. seismite, seismo-olistostrome, and seismo-turbidite）. Paleoseismic records developed in the Zhushadong Formation are mainly seismites with soft-sediment deformation structures, such as liquefied diapir, small liquefied-carbonate lime-mud volcano, liquefied vein, liquefied breccia, convolute deformation （seismic fold）, graded fault, soft siliceous vein, and deformation stromatolite, as well as seismites with brittle deformation structures of semiconsolidated sediments. Paleoseismic records preserved in the Liguan Formation are not only seismo-olistostrome with a slump fold, load structure, and ball-and-pillows, but also seismo-turbidite with convolution bedding, graded bedding and wavy-bedding. However, in the western Shandong area, the closer to the Yishu fault zone, the greater the thickness of the Liguan Formation and the Zhushadong Formation, the greater the number and type of layers with paleoseismic records, and the higher the earthquake intensity reflected by associations of seismic records. This evidence indicates that tectonic taphrogenesis accompanied by strong earthquake events occurred in the Yishu fault zone during the initial stage of the Caledonian Movement, which embodied the break-up of the Sino-Korean Plate along the Paleo-Tanlu fault zone at that time.

On tectonic movement in the South China Sea during the Cenozoic

The tectonic movement taking place at the end of Cretaceous and the beginning of Cenozoic had opened the Cenozoic phase of polycyclic tectonic movements,then the whole crust of the South China Sea had been mainly subjected to the regional stress field of tectonic tension,which was characterized by rifting depression.Seven times of regional tectonic movement and sedimentation had been assembled into a geological development history of polycyclic oscillation.Especially,the tectonic movements were strongly intensified at the end of Cretacious and the beginning of Paleagene,between Late Eocene and Mid-Oligocene,during Mid-and Late Miocene.These three times of tectonic movement had built the most important regional tectonic interfaces in the South China Sea.Crust movements of the South China Sea were the result and epitome of interaction of the Eurasia,Pacific and Indo-Australia plates,that is,they were introduced by polycyclic changes of directions,rates and strengths of lithospheric movements and asthenospheric flows across the Pacific and Indo-Australia plates.

Present-day tectonic movement in the northeastern margin of the Qinghai-Xizang (Tibetan) plateau as revealed by earthquake activity

Characteristics of present-day tectonic movement in the northeastern margin of Qinghai-Xizang plateau (Tibetan) are studied based on earthquake data. Evidence of earthquake activity shows that junctures between blocks in this area consist of complicated deformation zones. Between the Gansu-Qinghai block and Alxa block there is a broad compressive deformation zone, which turns essentially to be a network-like deformation region to the southeast. The Liupanshan region, where the Gansu-Qinghai block contacts the Ordos block, is suffering from NE-SW compressive deformation. Junction zone between the Ordos and Alxa block is a shear zone with sections of variable trend. The northwestern and southeastern marginal region of the Ordos is under NNW-SSE extension. The above characteristics of present-day tectonic deformation of the northeastern Qinghai-Xizang plateau may be attributed to the northeastward squeezing of the plateau and the resistance of the Ordos block, as well as the southeastward extrusion of the plateau materials.

A Discussion on the Characteristics of Tectonic Transformation and Its Mechanism of 2nd Episode of Zhu-Qiong Movement in Zhu 1 Depression, South China

Based on the detailed interpretation of high-accuracy 3D seismic data, the characteristics of regional unconformities, fracture systems, sedimentary filling and paleo-stress field in Zhu 1 depression were comprehensively analyzed. The results showed that 2nd episode of Zhu-Qiong movement was an important tectonic transformation that occurred during rifting, basin structure patterns above and below the regional angular unconformity caused by 2nd episode had distinct differences. The orientations of those basin-controlling faults changed from NE, NEE to EW, NWW, which indicated that the paleo-stress field veered from NNW extension clockwise to sub-NS extension and basin structures patterns transformed from NE, NEE strong rifting to sub-EW, NWW weak rifting. The depocenter showed seesaw-like migration from S to N. And the sedimentary systems transformed from semi-deep-deep lacustrine facies to braided river delta facies developed in shore-shallow lacustrine. Combined with its tectonic recombination of periphery plates that period, the mechanism of above tectonic transformation had direct correspondence to the readjustment of the Indian plate and the Pacific plate. The southward subduction of the pro-to-south China Sea is the direct cause of this tectonic transformation.

Correlation between Tectonic Environment and Chracteristics of Mass Movement （Landslides）： A Case Study from Java, Indonesia

In Central Java and Yogyakarta Special Region, there are several zones, which potential of landslide disaster. The zones are in general located at uplitted and or folded mountains, such as North Serayu Mountains, South Serayu Mountains, Menoreh Mountains, Southern Mountains and slopes of young volcanic area, including Ungaran-Merbabu-Merapi area, and Slamet-Sundoro-Sumbing area. Besides morphology, another main factor influencing vulnerability of the terrain is physical properties of the composing lithology. The geologic formations in the study area are predominantly composed of clayey and volcanic rocks. The cohesion force of clayey rock ranges 0.4-0.7 kg/cm^2, the internal friction angle ranges 20°-35°, while the cohesion force of volcanic rock （weathered） ranges 0.25-0.27 kg/cm^2, and the friction angle ranges 20°-35°. In general, rocks occupying the area are collectively dissected by joints and active faults, with soil of more than 5 m thick. Local rainfall belongs to high category （〉 2,500 mm/y）. However, landslides that occur in each physiographic zone mentioned above show different characterizations.

Responses of landform development to tectonic movements and climate change during Quaternary in Fenhe drainage basin

Tectonic movements and climate changes are two main controllers on the development of landform. In order to reconstruct the history of the evolution of the landform in the Fenhe drainage basin during middle-late Quaternary comprehensively, this paper has provided a variety of geomorphological and geologic evidences to discuss how tectonic movements and climate changes worked together to influence the landform processes. According to the features of the lacustrine and alluvial terraces in this drainage basin, it is deduced that it was the three tectonic uplifts that resulted in the three great lake-regressions with an extent of about 40-60 m and the formation of the three lacustrine terraces. The times when the tectonic uplifts took place are 0.76 MaBP, 0.55 MaBP and 0.13 MaBP respectively, synchronous with the formation of paleosol units S 8 , S 5 and S 1 respectively. During the intervals between two tectonic uplifts when tectonic movement was very weak, climate changes played a major role in the evolution of the paleolakes and caused frequent fluctuations of lake levels. The changes of the features of lacustrine sediment in the grabens show the extent of such fluctuations of lake level is about 2-3 m.

The Vertical Deformation and Horizontal Displacement Fields,Movement, and Seismicity of the Island Arc Tectonics

In this work,the vertical deformation,horizontal displacement,and stress fields of arcuate tectonics are theoretically derived from the horizontal tectonic stress; then the characteristics of tectonic movement,seismicity,and focal mechanism of arcuate tectonics of the entire world are explained.It is pointed out that the island arc and other arcuate tectonics are gradually developed under the displacement and stress fields of the arcuate tectonics and that the under-thrusting action of the ocean plate is secondary.The distance formulas between the volcanic arc and the trench are suggested and also that theoretical results are consistent with actual data.

Cosmic Expansion: The Dynamic Force Source for All Planetary Tectonic Movements

In this paper, the relationship between the geodynamics and cosmic expansion is analyzed and demonstrated from the basic physical principles and various natural phenomena, and the conclusion is drawn that cosmic expansion is the dynamic force source of all planetary tectonic movements in the universe. The energy for the formation and change of landscape and the energy of earthquakes and volcanic eruptions all come from the cosmic expansion. With the cosmic expansion, the energy density of space is decreasing, the atoms and molecules of all matter in the universe are growing, and the magma is expanding and producing gases. As the earth’s internal pressure rises, the mechanical energy that accumulates within the magma forms the driving force of the earth’s various tectonic movements, and the release of these energy and matter (expansive magma and high-pressure gases) leads to the formation and the changes of the landform (such as orogenesis, epeirogenesis, the formation of the earth’s plates, the Earth expansion, the seafloor spreading, and the continental drift), as well as to earthquakes and volcanic eruptions. In this paper, the causes of all kinds of earthquakes, especially deep focus earthquakes, are given and almost all known seismic phenomena are explained, the basic principle and method of earthquake prediction are given, and the direction is pointed out for the elimination of earthquakes and the utilization of earthquake energy. Based on the same principle of physics, this paper also shows that the Ice-Age is caused by the acceleration of the speed of the motion of the solar system relative to the Milky Way in certain regions of the Milky Way. The greater the speed of the solar system relative to the Milky Way, the greater the drop in Earth surface temperature.

The evolution of the coral reefs in the middle and north parts of the South China Sea and its relation with tectonic and eustatic movements

In this paper, the morphogenesis, stratigraphic sequences and dates of the coral reefs in the middle and north parts of the South China Sea are discussed, the position of the distributary regions of Cenozoic coral reefs in plate tectonics, the relationships of coral-reef evolutionary characteristics and dates with sea-basin spreading. Neogene sea-water transgression and Quaternary global climate-eustatic fluctuation are expounded and proved, and the latitudinal variation of the distribution of coral reefs in various geologic times are summed up.

The Cenozoic activities of Yangjiang-Yitongdong Fault: insights from analysis of the tectonic characteristics and evolution processes in western Zhujiang(Pearl) River Mouth Basin

The Yangjiang-Yitongdong Fault (YJF) is an important NW-trending regional fault, which divides the Zhujiang (Pearl) River Mouth Basin (ZRMB) into western and eastern segments. In Cenozoic, the northern continental margin of the South China Sea (SCS) underwent continental rifting, breakup, seafloor spreading and thermal subsidence processes, and the Cenozoic activities of YJF is one part of this series of complex processes. Two long NW-trending multichannel seismic profiles located on both sides of the YJF extending from the continental shelf to Continent-Ocean Boundary (COB) were used to study the tectonic and sedimentary characteristics of western ZRMB. Using the 2D-Move software and back-stripping method, we constructed the balance cross-section model and calculated the fault activity rate. Through the comprehensive consideration of tectonic position, tectonic evolution history, featured structure, and stress analysis, we deduced the activity history of the YJF in Cenozoic. The results showed that the YJF can be divided into two segments by the central uplift belt. From 65 Ma to 32 Ma, the YJF was in sinistral motion as a whole, inherited the preexisting sinistral motion of Mesozoic YJF, in which, the southern part of YJF was mainly in extension activity, controlling the formation and evolution of Yunkai Low Uplift, coupled with slight sinistral motion. From 32 Ma to 23.8 Ma, the sinistral motion in northern part of YJF continued, while the sinistral motion in southern part began to stop or shifted to a slightly dextral motion. After 23.8 Ma, the dextral motion in southern part of YJF continued, while the sinistral motion in northern part of YJF gradually stopped, or shifted to the slightly dextral motion. The shift of the YJF strike-slip direction may be related to the magmatic underplating in continent-ocean transition, southeastern ZRMB. According to the analysis of tectonic activity intensity and rift sedimentary structure, the activities of YJF in Cenozoic played a regulating role in the rift extension process of ZRMB.

Identification of Five Stages of Dike Swarms in the Shanxi-Hebei-Inner Mongolia Border Area and Its Tectonic Implications

Dike swarms are generally ascribed to intrusion of mantle-source magma result from extension. Basic dike swarms around the Shanxi-Hebei-Inner Mogolia borders in the northern peripheral area of the North China Craton can be divided into five age groups according to isotopic dating: 1800-1700 Ma, 800-700 Ma, 230 Ma, 140-120 Ma, and 50-40 Ma. Geological, petrological and isotope geochemical features of the five groups is investigated in order to explore the variation of the mantle material composition in the concerned area with time. And the various extensional activities reflected by the five groups of dike swarms are compared with some important tectonic events within the North China Craton as well as around the world during the same period.

Modern tectonic stress field in the Chinese mainland inverted from focal mechanism solutions

The inversion of modern tectonic stress field in China is made by regions on the basis of focal mechanism data inthe period of 1920-1996. Results of the inversion show that the maximum principal compressive stress σ1 axisstrikes nearly north-south direction in the Tibet Plateau and western Chin4 east-west direction in North China Incentral China, its strikes show a radiate pattern, i.e., north-north east in north part, east-west in central part andnorth-north west in south part. The σ1 axes are often perpendicular to the minimum principal stress σ3 axes, exceptwestern China where the σ1 axes are oblique to the σ3 axes with an acute angle. R is defined by (σ2-σ1)/(σ3-σ1),has the higher values (0.60-0.90) in north part of central China and quickly changes into the lower values(0. 10-0.30) in the Tibet Plateau. Both of the observed and inverted fault planes have strikes varying with locations.Combining stress directions and R value, the stress configuration is divided into 7 groups. Most of the groups showstrike-slip faulting with intermediate R values, which occupies North China and the eastern part of China as well asinner Tibet Plateau. A few of them show reverse faulting with higher R values within western pod of China and thenorth edge of the Tibet Plateau. Normal faulting occurred on the south edge of the Tibet Plateau with smaller Rval nes.

Late Cenozoic Tectonic Deformation in the Dongsha Islands and Adjacent Sea Area

Dongsha Island and the adjacent sea area locate at the northern continental margin of the South China Sea (SCS), and is connected to the east by the Manila Trench. Analyses of seismic stratigraphy and gravity, magnetic and drilling wells data led to the discovery of three post fault sequences (V, VI, VII). Extensive tectonic uplift, magma activity and erosion occurred in Dongsha Island and the adjacent area, where most of the faults in the northeastern SCS were still active during Pliocene and Quaternary. Two groups of faults trending NEE and NW were developed during Late Cenozoic. We conclude that three important tectonic movements, especially Dongsha movement (4.4-5.2 Ma) and Liuhua movement (1.4-1.89 Ma), controlled the structural framework in the Dongsha rise; whose deformation in the east is stronger than that in the west and whose stress field variation suggests that the tectonic uplift in the study area contributed to magmato tectonic events correlated to the main collision phases between the East China and Taiwan 5-3 and 3-0 Ma ago.

Coal forming environments and their relationship to tectonic activity in the Cévennes Stephanian coal basin

Coal forming environments in the tectonically controlled intermontane Stephanian Cévennes coal basin (Massif central, France) show a complex interelationship between structural and sedimentological features. The study of the general structural features and the geometry of the coal beds developed during the different stages in the evolution of the basin, and the spatial relation of the lithofacial units to the early tectonic activities, lead the authors to suggest the following model. The synsedimentary faults that occurred as both intrabasinal and marginal faults controlled not only the spatial distribution, shape and thickness of the detrital rock units and coal seams, but also caused the inversion of the tectonic style. The marginal faults exercised important controls on the geometry of the basin and the distribution of lithofacial units. However due to the subsidence of the central part of the basin and the depocenter, and the to differences in the timing and intensity of the displacement the coal enrichment zones shifted both vertically and laterally. This eventually resulted in the inversion of the whole tectonic framework from semi graben through graben to a new semi graben. The style and rate of the tectonic movement and basin filling that occurred in the Stephanian Cévennes coal basin were in turn closely linked with the tectonic movement in the surrounding area. Therefore the authors propose that the environment and processes of coal formation in this basin are closely linked to its tectonic evolution.

Preliminary study on isostatic anomaly and recent tectonic stress field-Taking East China Sea and its eastern marginal seas as an example

On the basis of the reality of recent tectonic movement and discarding such a viewpoint that the isostatic adjust-ment only results from excessive or insufficient compensation, we have discussed the tectonic stress causing ine-quality and regarded the isostatic anomaly as a load on the earths interior, thus the earths inner stress can be cal-culated. The research results show that in the East China Sea and its eastern marginal seas the change of the verti-cal stress derived from the isostatic gravity anomaly is more marked than that of the horizontal stress. Along the Ryukyu trench there is an enhancement of vertical stress by 5 MPa, which evidently reflects the effect of plate subduction. On contrary, along the island arc to the northwest of the trench the vertical stress weakens by about 5 MPa. The horizontal stresses in eastern and western parts are obviously different, the east westward stress on the oceanic crust sx is negative (while the pressure is positive) but on the continental crust is positive. These facts indicate the effect of compression between plates.

The abnormal mantle and deep tectonic process in the southern region of North China Plain

In this paper, based on the large scale uplift, lateral inhomogeneity and low interface velocity along the Moho as well as the soft low velocity layer under it obtained from deep seismic sounding (DSS), we deduced that the southern region of North China Plain is characterized by continental rift and abnormal mantle in the lithosphere.Summarizing geological and geophysical data, we try to state that the forming and developing of abnormal mantle and the intermittent activity of asthenosphere are the dynamic sources to dominate the geologic structure and tectonic movement in this region. We also point out that the research of deep process is important to probe timespace law of earthquake occurrence.

Cenozoic Tectonic Deformation and Related Geodynamics in the Western Part of Sichuan and Yunnan,Southwest China

Tectonic deformation of Cenozoic strata,youthful tectonontorphology,and high seismicity in the western part of Sichuan and Yunnan(Southwest China)marked intensive tectonism there during the Ceno7oic.It is a good place for studying the continental geodynamics because it is far away from those active plate boundaries surrounding the East Asian continent but near the southeastern margin of the Qinghai-Xizang(Tibet)plateau.The present study discriminated two phases of tectonic deformation with quite different styles in Cenozoic.Early compression deformation,expressed by folds,thrust,and even nappe structure,mainly occurred between the middle and late Eocene.Late extension deformation expressed by block-faulting started at least in the late Pliocene.Nonconformity,absence of strata,nonsuccessive tectonism,and inverse movement of the faults in late stages illustrated that two different deformation phases should be caused by different geodynamic processes.The early compression deformation would be related to

Recent crustal horizontal movement in the Chinese mainland

According to the results of careful re-proeessing of data obtained from two GPS survey campaigns of crustal movement monitoring network in Chinese mainland carried out in 1994 and 1996, the crustal horizontal movement characteristics in Chinesc mainland are studied in the paper.In the analysis, a relatively consummate deformation model in which the deformation is described by the relative movement between the tectonic blocks with interior strain and the corresponding analysis method are used. The magnitude of movement along the boundary zones between the tectonic blocks is calculated. And the characters and intensities between the main boundny zones are compared.

Recent crustal movement and great earthquakes in Qinghai-Tibet sub-plate

Crustal movement and incremental-movement data observed repeatedly at GPS stations during 1999 -2009 were analyzed to study the effect of two earthquakes of Ms8.1 and Ms8.0 that occurred in 2001 and 2008, respectively, in Qinghai-Tibet sub-plate and its eastern margin. The result revealed certain anoma- lous pre-earthquake deformation and some large co-seismic changes. Prior to the 2008 Wcnchuan Ms8.0 earthquake, the seismogenic Kunlunshan fault zone became a geographic boundary between different regional movements. At the time of the earthquake, there was an average cross-fault crustal shortening of - 1.04 m and an average right-lateral strike slip of 0.76 m along the ruptured segment, as well as a strain-energy release of -62.66 ×10.7.