Effects of formal credit on pastoral household expense: Evidence from the Qinghai-Xizang Plateau of China

Formal credit is critical in agricultural production,allowing more expenditure and productive input,thereby improving farmers'welfare.In pastoral China,formal financial institutions are gradually increasing.However,a limited understanding remains of how formal credit affects herders'household expenses.Based on a survey of 544 herders from the Qinghai-Xizang Plateau of China,this study adopted the propensity score matching approach to identify the effect of formal credit on herders'total household expenses,daily expenses,and productive expenses.The results found that average age,grassland mortgage,and other variables significantly affected herders'participation in formal credit.Formal credit could significantly improve household expenses,especially productive expenses.A heterogeneity analysis showed that formal credit had a greater impact on the household total expense for those at higher levels of wealth;however,it significantly affected the productive expense of herders at lower wealth levels.Moreover,the mediating effect indicated that formal credit could affect herders'household income,thus influencing their household expenses.Finally,this study suggests that policies should improve herders'accessibility to formal credit.

Crustal and uppermost mantle structure of the northeastern Qinghai-Xizang Plateau from joint inversion of surface wave dispersions and receiver functions with P velocity constraints

Lithospheric structure beneath the northeastern Qinghai-Xizang Plateau is of vital significance for studying the geodynamic processes of crustal thickening and expansion of the Qinghai-Xizang Plateau. We conducted a joint inversion of receiver functions and surface wave dispersions with P-wave velocity constraints using data from the Chin Array Ⅱ temporary stations deployed across the Qinghai-Xizang Plateau. Prior to joint inversion, we applied the H-κ-c method(Li JT et al., 2019) to the receiver function data in order to correct for the back-azimuthal variations in the arrival times of Ps phases and crustal multiples caused by crustal anisotropy and dipping interfaces. High-resolution images of vS, crustal thickness, and vP/vSstructures in the Qinghai-Xizang Plateau were simultaneously derived from the joint inversion. The seismic images reveal that crustal thickness decreases outward from the Qinghai-Xizang Plateau. The stable interiors of the Ordos and Alxa blocks exhibited higher velocities and lower crustal vP/vSratios. While, lower velocities and higher vP/vSratios were observed beneath the Qilian Orogen and Songpan-Ganzi terrane(SPGZ), which are geologically active and mechanically weak, especially in the mid-lower crust.Delamination or thermal erosion of the lithosphere triggered by hot asthenospheric flow contributes to the observed uppermost mantle low-velocity zones(LVZs) in the SPGZ. The crustal thickness, vS, and vP/vSratios suggest that whole lithospheric shortening is a plausible mechanism for crustal thickening in the Qinghai-Xizang Plateau, supporting the idea of coupled lithospheric-scale deformation in this region.

Influence of Qinghai-Xizang Plateau snow cover on interannual variability of Western North Pacific tropical cyclone tracks

Track density function(TDF)was computed for all Western North Pacific tropical cyclones(WNP TCs)tracks from 1950 to 2018,and the TDFs were further investigated using principal component analysis(PCA)to analyze their inter-annual spatial and temporal variability.Then,the relationships between each empirical orthogonal function(EOF)mode and the typhoon count,typhoon landfall count,track pattern,and the Qinghai-Xizang Plateau snow cover(QXPSC)were examined,and the possible physical mechanisms implied by the statistical relationship were explored.The results show the QXPSC significantly affected the surface-atmosphere heat exchange through snow cover(SC)level,then changed the East Asian summer monsoon regional circulation pattern,influenced the subtropical high-pressure system strength and location,and ultimately affected the WNP TCs track patterns and thus changed their landfall locations.

Interannual and Decadal Variations of Snow Cover overQinghai-Xizang Plateau and Their Relationships to Summer Monsoon Rainfall in China

Interannual and decadal variations of winter snow cover over the Qinghai-Xizang Plateau (QXP) are analyzed by using monthly mean snow depth data set of 60 stations over QXP for the period of 1958 through 1992. It is found that the winter snow cover over QXP bears a pronounced quasi-biennial oscillation, and it underwent an obvious decadal transition from a poor snow cover period to a rich snow cover period in the late 1970’s during the last 40 years. It is shown that the summer rainfall in the eastern China is closely associated with the winter snow cov-er over QXP not only in the interannual variation but also in the decadal variation. A clear relationship ex-ists in the quasi-biennial oscillation between the summer rainfall in the northern part of North China and the southern China and the winter snow cover over QXP. Furthermore, the summer rainfall in the four cli-mate divisions of Qinling-Daba Mountains, the Yangtze-Huaihe River Plain, the upper and lower reaches of the Yangtze River showed a remarkable transition from drought period to rainy period in the end of 1970’s, in good correspondence with the decadal transition of the winter snow cover over QXP. Key words Snow cover over Qinghai-Xizang Plateau - Summer monsoon rainfall in China - Interannual and decadal variations This study was supported by the National Key Programme for Developing Basic Sciences (G 1998040900 Part I).

VARIATION OF d δ^(18)O/dT IN PRECIPITATION IN THE QINGHAI-XIZANG PLATEAU

The relations between δ18O and temperature on the different time scales were analysed,according to the data from Tuotuohe (34°13’N, 96°25’E; 4533 m a. s. l. ), Delingha (37°22’N,97°22’E; 2981 m a. s. l. ) and Xining (36°37’N, 101°46’E; 2261 m a. s. l. ) in the Qnghai-Xizang Plateau. The results show that the significance of d δ18O/dT on different time scales are different.The d δ18O/dT on the synoptic scale reflects the interdependent relation between δ18O and temperature in the short-term synoptic scale process; the d δ18O/d T on the seasonal scale reflects the relation between them whithin a year; and the d δ18O/d T on the climatic scale reflects the relation between them in the long-term climatic change. The calculated d δ18O/dT on climatic scale is very close to the theoretical values on the condition of advection transport for Tuotuohe Station. However, there are great differences between the calculated and the theoretical values for Delingha and Xining stations.

Calculation of Solar Albedo and Radiation Equilibrium over the Qinghai-Xizang Plateau and Analysisof Their Climatic Features

Using radiation data from the Automatic Weather Stations (AWSs) for thermal balance obser-vations, which were set up at Lhasa, Nagqu, Xigaze and Nyingchi by the Sino-Japanese Asian Monsoon Mechanism Co-operative Project in 1993–1996, and 1985–1989 Earth Radiation Balance Experiment (ERBE) measurements of Langley Research Center/NASA of US, and 1961–1996 monthly mean data from 148 surface stations over the Qinghai-Xizang Plateau (QXP) and its neighborhood, study is performed on empirical calculation methods of surface albedo, surface total radiation, planetary albedo and outgoing longwave radiation with the climatic features of radiation balance at the surface and the atmospheric top examined. Evidences suggest that the empirical formulae for surface albedo, planetary albedo, surface to-tal radiation and outgoing longwave radiation from the atmospheric top are capable of describing their seasonal and interannual variations over the QXP. The surface albedo is marked by noticeable seasonal variation and yearly mean of 0.22 with the maximum of 0.29 in January and minimum of 0.17 in July and August; in winter the albedo has great horizontal difference, bigger in the moun-tains than in the river valleys, and small in summer. The planetary albedo shows a smaller range of its annual variation with the yearly mean of 0.37, the maximum (minimum) occurring in February and March (autumn). In winter its high-value regions are mainly at Gar (Shiquanhe) in the western QXP and from the southwestern Qinghai to the northeastern Tibet and the low-value area at the northern slope of the central Himalayas; in summer, however, the albedo distribution displays clear-ly a progressive decrease from southeast to northwest. As for the surface total radiation, its values and annual varying range are smaller in the east than in the southwest. Its high-value center is at the southern slope of the Himalayas in winter and makes a conspicuous westward migration in spr-ing, remaining there for a long time, and it begins to retreat eastward in autumn. Monthly mean values of the surface net radiation are all positive and larger in summer than in winter. The net ra-diation is significantly intensified under the combined effect of surface total radiation and surface albedo from spring to early summer, resulting in the strongest sector in the mid plateau with its center staying nearly motionless from March to September, and is reduced in autumn dominantly by surface effective radiation. The earth-atmosphere system loses heat outward from October to next February and gains in other months. On an average, the plateau gains heat of 15 W m-2 on an annual basis. Key words The Qinghai-Xizang Plateau - Albedo - Radiation balance - Climatic feature (1)This work was supported under the auspices of the National (G1998040800) and CAS’s Key Project for Basic Research on Tibetan Plateau (KZ951-A1-204; KZ95T-06).

Evolution characteristics of Quaternary tectonic stress field in the north and east margin of Qinghai-Xizang plateau

By inversion of fault slip data for Quaternary tectonic stress field and the analysis of crustal deformation after lateTeriary. we explaincd the evolution of crustal dynamic about the north and east margin of Qinghai-Xizang (Tibet)plateau since Miocenc. From middle or late Miocene to early Pleistocene, the tectonic stress field was featured by amaximum principal compression which was coming from the collision of india Plate continued to the boundaryof the plateau. and was basically of reverse faulting type. Since the late period of early Pleistocene, Pleistocene continuedto push northward and the compressional deformation of the plateau interior increased continuously, meanwhile,N W-SE extension appeared on the east side of the plateau. This formed a favorable condition for the interior block offoe plateau to slide towards east and southeast, causing the faults surrounding the plateau to change from thrust tostrike-slip. -The contemporary tectonic stress field was formed from the late period of early Pleistocene and continuedto present. The direction of maximum principal compressional stress rotated clockwise with respect to the previoustectonic stress held. the stress field was mainly of strike-slip type.

LAST GLACIATION AND MAXIMUM GLACIATION IN THE QINGHAI-XIZANG (TIBET) PLATEAU: A CONTROVERSY TO M. KUHLE,S ICE SHEET HYPOTHESIS

Since the late 1950’s, many Chinese scientists have explored the remains of the Quaternary glaciation in the Qinghai-Xizang (Tibet) Plateau and its surrounding mountains. In the main, 3-4 glaciations have been recognized. The largest one occurred in the Late Middle Pleistocene with piedmont glaciers, ice caps and trellis valley glaciers in many high peak regions. But here is no evidence of a unified ice sheet covering the whole plateau as described by M. Kuhle. Due to the further uplifting of the Himalayas and Qinghai-Xizang Plateau the climate became progressively drier, diminishing the extension of glaciers during the Late Pleistocene. The elevation of the snow line during the Last Glaciation was about 4,000 m on the south, east and northeast edges of the plateau and ascended to 5500 m on the hinder northwest of the plateau. The thermal effect of the big plateau massif, the sharp increase of aridity from the southeast rim to the northwest inland area and the abrupt decrease of precipitation during

Structural Variation of an Atmospheric Heat Source over the Qinghai-Xizang Plateau and Its Influence on Precipitation in Northwest China

NCEP/NCAR reanalysis data and a 47-year precipitation dataset are utilized to analyze the relationship between an atmospheric heat source （hereafter called 〈 Q1 〉） over the Qinghai-Xizang Plateau （QXP） and its surrounding area and precipitation in northwest China. Our main conclusions are as follows： （1） The horizontal distribution of 〈 Q1 〉 and its changing trend are dramatic over QXP in the summer. There are three strong centers of 〈 Q1 〉 over the south side of QXP with obvious differences in the amount of yearly precipitation and the number of heat sinks predominate in the arid and semi-arid regions of northwest China （NWC）, beside the northern QXP with an obvious higher intensity in years with less precipitation. （2） In the summer, the variation of the heat source＇s vertical structure is obviously different between greater and lesser precipitation years in eastern northwest China （ENWC）. The narrow heat sink belt forms between the northeast QXP and the southwestern part of Lake Baikal. In July and August of greater precipitation years, the heating center of the eastern QXP stays nearly over 35°N, and at 400 hPa of the eastern QXP, the strong upward motion of the heating center constructs a closed secondary vertical circulation cell over the northeast QXP （40~ 46~N）, which is propitious to add precipitation over the ENWC. Otherwise, the heating center shifts to the south of 30°N and disappears in July and August of lesser precipitation years, an opposite secondary circulation cell forms over the northeast QXP, which is a disadvantage for precipitation. Meanwhile, the secondary circulation cell in years with more or less precipitation over the ENWC is also related to the heat source over the Lake Baikal. （3） The vertical structure of the heat source over the western QXP has obvious differences between greater and lesser precipitation years in western northwest China in June and July. The strong/weak heat source over the western QXP produces relatively strong/weak ascending motion and correspondingly constructs a secondary circulation cell in lesser/greater precipitation years.

Changes and spatial patterns of the differences between ground and air temperature over the Qinghai-Xizang Plateau

The difference between ground soil and air temperature （Ts-Ta） was studied by using the data of ground and air temperature of 99 stations over the Qinghai-Xizang （Tibet） Plateau from 1960 to 2000,and its spatial distribution and time changing tendency have been diagnosed by principal component analysis and power spectral analysis methods. The results show that the values of （Ts-Ta） are the maximum in June and the minimum in December. The first three loading eigenvectors, which reflect the main spatially anomalous structure of （Ts-Ta） over the Qinghai-Xizang Plateau, contain the contrary changing pattern between the northwestern and the southeastern regions, the pattern response of the sea level elevation and the geography, and the pattern response of the distribution of the permafrost. There are four patterns of time evolution including the patterns of monotonous increasing or decreasing trends, the basic stability pattern and the parabola pattern with the minimum value. （Ts-Ta） has a periodic variation about 2 years. According to the spatial distribution of the third loading eigenvectors of （Ts-Ta） over the Qinghai-Xizang Plateau in cold season, the permafrost response region and the seasonal frozen ground response region are identified.

A PRELIMINARY STUDY ON TRE ZONE OF ALPINE SCRUB AND MEADOW OF QINGHAI-XIZANG (TIBETAN) PLATEAU

The zone of alpine scrub and meadow, characterized by highlandsubpolar humid/subhumid climate, is a transitional area from deep gorges to theplateau proper.The natural zone is unique in physical environments and naturalecosystems, and could not be found at the lowlands elsewhere on the earth.Thepredominant type of vegeation is alpine meadow, including Kobresia meadow,herbaceous meadow and swampy meadow. It is an important pasturelands ofanimal husbandry for Tibetan on the plateau. Main vegetion types, animal groups,characteristics of alpine meadow soils, the altitudinal belt and the horizontalzonality of the natural zone, as well as utilization and management of the grasslandsare discussed in the present paper.

The property, age and formation environment of the palaeokarst in Qinghai-Xizang Plateau

The karst landforms distributed on the Qinghai-Xizang (Tibet) Plateau can be genetically classed with the Tertiary underground karst, which were gradually exhumed to the surface with the uplift of the plateau during Quaternary period. The relative deposits of the Tertiary palaeokarst processes, such as the residuum and speleothem, were discovered recently in the southern and southeastern fringe areas of the plateau, where has geological-currently been disintegrated by the headward erosion processes of the modern river systems. The major chemical components of the clay portion of the residuum consist mainly of SiO2, Al2O3 and Fe2O3. The clay minerals composition of the clay portion belongs to illite-kaolinite pattern for most of the residuum samples, and kaolinite-illite pattern for a few of the samples. It can be judged from the silicic acid index and the clay minerals composition that the formation of the residuum of the Plateau was in its initial phase. However, such a lower chemical weathering index only reflected the weathering degree in the bottom or lower parts of the lateritic weathering crust. The relatively intensive chemical weathering processes of the surface layers of the lateritic weathering crust could be logically speculated. The surface feature textures of quartz grains in the residuum were formed mainly by the chemical erosion, which revealed a long-term humid-tropical environment when the residuum and the palaeokarst formed.

Simulation analysis on characteristics of land surface over western Qinghai-Xizang Plateau during freez-ing-thawing period

Using the Global Energy and Water Cycle Experiment-Asian Monsoon-Tibet Plateau Experiment (GAME-Tibet) observa-tional data-from October 2002 through September 2003-of Gaize in the western Qinghai-Xizang Plateau (QXP),the land-surface characteristics of the Qinghai-Xizang Plateau are simulated by the improved land-surface model Common Land Model (CoLM).The results show that CoLM can reproduce the land-surface characteristics of plateau areas well.In the sur-face-energy balance of the western QXP in the winter half year,the sensible heat (SH) flux constituted the dominant energy,and the latent heat (LH,here and after) flux is very small.Although the LH flux nearly equals zero in freezing season,it cannot be ig-nored during the period of freezing-thawing in QXP.In the transition season from midto late-May,the frequent phase change of soil water that is caused by the freezing-thawing process leads to the increase of LH flux and decrease of the Bowen ratio.The simulation results also indicate that the changes of surface effective heat fluxes (SH and LH flux) are associated with precipitation and the frequent change between freezing and thawing processes in soil surface.

Review of numerical simulation on the dynamics of Qinghai-Xizang plateau

In recent twenty years, much numerical simulation work has been done on the evolution of Qinghai-Xizang (Tibetan) plateau. In this paper some principal numerical models and results are reviewed and analyzed. The earlier plane stress or plane strain model has much discrepancy with the actual deformation of Qinghai-Xizang plateau, such as the thickening of Tibetan crust and the lateral extrusion of Tibet along strike-slip faults. The thin viscous sheet model and the thin-plate model may simulate the change of the crustal thickness and the deformation pro-duced by gravitational force. It is suitable for studying the large-scale and long-time deformation. The influence of faults on the deformation of Tibetan plateau should be further studied.

NUMERICAL STUDY ON INFLUENCE OF QINGHAI-XIZANG(TIBETAN)PLATEAU ON SEASONAL TRANSITION OF GLOBAL ATMOSPHERIC CIRCULATION

It is a worthwhile attempt to address the role of the Qinghai-Xizang Plateau in the seasonal transition of general circulation from a global prospective. In this paper, the CCM1 (R15L7) - LNWP spectral model is used to study the influences of the Qinghai-Xizang Plateau on the seasonal transfer of the general circulation, with the objective analysis form the State Meteorological Center for March 17, 1996 as the initial field. A mid-level heating source in regions on the same latitudes is shown to cause a warming center of 224 K to form on the level of 200 hPa that warms up the atmosphere by more than 7 K and a drop of temperature by about 6 K on most of the 200-hPa layer over the Antarctic continent, with the largest negative center being -8.28 K. It is favorable to the deepening and widening of the polar vortexes in the course of transition from summer to winter. The topographic effect of the plateau plays a vital role in forming and maintaining the mean troughs and ridges of the atmospheric circulation in Northern Hemisphere such that it strengthens (weakens) the south-north positive gradient of temperature on the northern (southern) side of the latitude zone in which the plateau sits and increases the north-south gradient of temperature near 30(N. The seasonal transition is thus favored so that the bulk travel of global westerly at the middle latitudes and the formation of Asian monsoon in early summer are made possible. In the equatorial and low-latitude areas where the geopotential is increased, the effect of the plateau terrain is also evident in that it is favorable for the northern withdrawal of the tropical high ridge in Southern Hemisphere and the northern shift of the subtropical high in Northern Hemisphere. In addition, the effect also helps increase the polar easterly over the Southern Hemisphere and weaken the low zone at 500 hPa. It acts as an increasing factor for the polar vortex around the Ross Sea and contributes to the genesis of the Somali Jet on the equator.

EVOLUTION AND DIFFERENTIATION OF THE PHYSICO-EOGRAPHICALENVIRONMENT OF THE QINGHAI-XIZANG (TIBETAN) PLATEAU

The intense uplift of the Qinghai-Xizang Plateau givesrise to drastic changes of natural environment and distinctdifferentiation of the Plateau proper. This paper focuses on theevolution of subtropical environment at low altitude to frigidenvironment at high altitude of the region since Pliocene and thechanges effected by cold-warm amplitude bf global change. Bycomparative study on the structure-type of the altitudinal belt, adistributional model diagram with close relevance to highlanduplift effect has been generalized. Based on regjonaldifferentiation of the Qinghai-Xizang Plateau, a number ofstriking geo-ecological phenomena such as moisture corridor, dryvalleys and high cold-arid core area are investigated anddiscussed.

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 NEW INTERPRETATION OF THE EVOLUTION OF THE TETHYS CRUSTOBODY AND THE PETROLEUM POTENTIAL OF THE QINGHAI-XIZANG (TIBET) PLATEAU

Although large amounts of data have been collected during the past 30 yesrs in the study of the formation, evolution and dynamics of the Tethys Sea by the use of the theory of plate tectonics, a large volume of geological and geophysical information has also been accumulated which cannot be explained by the plate tectonic hypothesis. For example, the Qinghai-Xizang Plateau is underlain by many thousands of meters of Ordovician through Eocene, gently-dipping, essentially undeformed, stable platform sequences. Stratigraphic and tectonic investigations reveal that the plateau-wide east-west fracture zones, interpreted as "sutures" in a plate-tectonic model, are not sutures at all. On the other hand, from the Late Carboniferous to the beginning of the Early Permian, it was impossible for the Tethys ocean with a width of several thousand kilometers to."open" and "close" (the speed could not be so great). The east-west fracture zones, with very sharp angles, exerted no control over deposition. Stress analysis of magmatic activity indicates that the Himalayan zone is presently under compression, the Gangdise zone under interwoven comprepsion and tension, and the Qinghai and Deccan Plateaus under weak tension. Lateral compression caused by weak tension at the northern and southern terminations was not enough for Xizang and its surroundings between India and Qinghai Province of China with an area of 2,400,000 km2 to rise to a height of 4,000 m above mean sea level. The authors believe that surge tectonics is the force driving the evolution of the Tethys Sea and the rising of the Qinghai-Xizang Plateau. G. G. T. demonstrates that two surge channels, an upper and a lower, exist in the Yadong-Anduo litho sphere, and the upper mantle in the southern part is uplifted. During the Eocene, as a result of tectogenesis, molten magma poured out from the channel along the Yarlung Zangbo River,forming ophiolites and melanges, and earthquakes and terrestrial heat are also distributed along the fracture zone. Likewise, at an earlier time the Banggong Co-Nujiang and Longmu Co-Yushu Jinshajiang surge channels and their fracture zones formed. During the Miocene, the three surge channels merged laterally, and then the unified rise of the Qinghai-Xizang Plateau took place. The formation and evolution of the surge channels resulted in a variety of worthy Paleozoic, Mesozoic and Cenozoic exploration targets and a series of sedimentary basins with the largest Qamdo Basin occupying 120, 000 km2 with sediments attaining a thickness of 15, 000 m. These basins contain multiple source-beds, reservoirs, traps and seals of different ages, showing oil and gas every-where. In the northern part lithology and facies are more stable than in the southern, and subsequent tectonic overprinting and volcanic activity are relatively weak. At present commercial oil flow has been penetrated by drilling in the Tertiary Lunpola Basin.

STREAMFLOW CHARACTERISTICS OF THE EASTERN QINGHAI-XIZANG PLATEAU

The eastern Qinghai-Xizang (Tibet) Plateau is the headwater area for many large Asian rivers. Permafrost occurs above 4,200 m a.s.l. and glaciers occupy the summits and high valleys of the east-west trending mountain chains. Annual runoff generally increases with precipitation which is augmented southward by the rise in topography. Rainfall, snow melt, glacier melt and groundwater are the primary sources of stream flow, and the presence of permafrost enhances the flashiness of runoff response to rainfall and snowmelt events. Peak flows are concentrated between June and September. And winter is low flow season. Three types of runoff patterns may be distinguished according to their primary sources of water supply: snowmelt and rainfall, glacier melt and snowmelt, and groundwater. Large rivers generally drain more than one environments and their runoff regime reflects an integration of the various flow patterns on the plateau.

Relocation of earthquakes in northeastern region of Qinghai-Xizang plateau and characteristics of earthquake activity

The northeastern region of Qinghai-Xizang plateau is the junction part of the Qinghai-Xizang block, Alxa block and ordos block. To explore tectonic feature of this region 4 study profiles are selected by taking gcological background into consideration. The ML≥3.0 earthquakes located within 40 km on both sides of the selected profiles and ML≥4.0 earthquakes in the studied region have been relocated. Of the 388 relocated earthquakes, 36% shift their previously determined epicenters by more than 5 km. The amount of relocated earthquake with focal depth determination increases 50% more than that before relocation. In this quasi-trijunction region of the northeastem of Qinghai-Xizang plateau three m≥8 earthqutas occurred historically and microearthquates are quite active at present,implying a strong tectonic activity persists here to the present day.