Situated as the eastern boundary of the Sichuan-Yunnan block, the Xianshuihe fault system exhibits a notably high left-lateral strike-slip rate, establishing itself as one of the most active regions for seismic activity in the Chinese mainland, profoundly influencing the occurrence of large earthquakes within the region. The fault zone and its surrounding area are relatively densely populated, intersecting with the famous Sichuan-Xizang National Highway No. 317 and No. 318 and serving as a significant focal point in the design of the Sichuan-Xizang railway. Given its substantial seismogenic capacity and associated earthquake risk, notable attention is warranted. Notably, on September 5, 2022, a left-lateral strike-slip M_S6.8 earthquake struck Luding County, Ganzê Prefecture, Sichuan Province, rupturing the Moxi fault of the Xianshuihe fault zone within the southeastern margin of the Qinghai-Xizang Plateau. Our study used Sentinel-1 SAR images to obtain both the interseismic deformation (2014-2020) and coseismic deformation resulting from the 2022 Luding M6.8 earthquake. Furthermore, we estimated the fault slip rate and locking depth during interseismic periods and inverted the coseismic slip distribution model. Utilizing the co-seismic dislocation model, we quantified Coulomb stress changes on surrounding fault planes induced by the Luding event. Finally, we provide an in-depth discussion on the seismogenic structure of the Luding earthquake and offer insights into the future seismic hazard implications associated with the Moxi fault and its adjacent faults.

We collected Sentinel-1 SAR imagery data spanning from October 2014 to April 2020 for both the descending orbit T135 and ascending orbit T026, and calculated the Line-of-Sight(LOS)direction deformation during the interseismic period covering the Moxi Fault of the Xianshuihe fault zone. The InSAR-derived interseismic deformation presented in this study effectively captures the long-term slip behavior of the seismogenic fault associated with the 2022 Luding earthquake. Our analysis reveals an aestimated slip rate of(5.9±1.8)mm/yr along the Moxi Fault. Combined with the GNSS and InSAR deformation observations, we generated a fused three-dimensional deformation field characterized by high density and precision. Additionally, we calculated the strain rate field based on the three-dimensional deformation within the study area. Our findings indicate pronounced shear deformation near the Moxi Fault, with strain highly concentrated along the fault trace. Notably, the strain concentration in the southern section of the Moxi Fault surpasses that observed in the northern section before the earthquake event. Furthermore, our analysis suggests that the Moxi Fault was locked at shallow depths before the earthquake occurrence, indicating a predisposition for seismic activity. The Luding earthquake thus transpired within the context of a seismically active background associated with the Moxi Fault.

Following the 2022 Luding 6.8 earthquake, we acquired InSAR coseismic deformation data within the seismic region, revealing predominantly horizontal surface displacements induced by the event. Employing the Most Rapid Descent Method(SDM), we conducted inversion of the fault plane slip distribution resulting from the earthquake. Our analyses indicate maximal dislocation quantities located south of the central earthquake zone, indicative of predominantly pure strike-slip movement. Dislocations are primarily observed at depths ranging between 5km to 15km, with the maximum left-lateral strike-slip dislocation measuring 1.71m and occurring at a depth of approximately 10km. In the north of the epicenter, fault slip manifests as predominantly sinistral strike-slip motion with a partial thrust component, exhibiting a progressively deepening slip pattern towards the northern region.

Utilizing the coseismic slip distribution derived from the 2022 Luding M_S6.8 earthquake, we conducted calculations to assess the Coulomb stress changes induced by the coseismic dislocation effects across the fault plane of the Moxi Fault and its surrounding major fault zones. These fault zones include the Xianshuihe fault zone(comprising the Moxi, Yalahe, Selaha, Zheduotang, and Kangding segments), the Anninghe fault zone(encompassing the Shimian-Mianning and Mianning-Xichang segments), the Zemuhe Fault zone, and the Daliangshan fault zone(comprising the Zhuma, Gongyihai, Yuexi, Puxiong, Butuo, and Jiaojihe segments).Our analysis reveals that the Luding earthquake caused a substantial decrease in Coulomb stress within its rupture section, resulting in the formation of a stress shadow area in the southern segment of the Moxi Fault. However, it significantly increased the Coulomb stress in the northern section of the Moxi Fault that was not ruptured in the earthquake. Concurrently, the Coulomb stress on the fault plane increases significantly in the southeast section of the Zheduotang fault, the northwest section of the Shimian-Mianning segment of the Anninghe fault zone, as well as the southeast section of the Zhuma segment, and the southeast section of the Gongihai segment of the Daliangshan fault zone.

The seismogenic structure of the 2022 Luding earthquake is a part of the Moxi Fault of the Xianshuihe fault zone. However, the magnitude and rupture length of the earthquake are significantly smaller than that of the Moxi M7$\frac{3}{4}$ earthquake in 1786, resulting in a less pronounced stress unloading effect. Additionally, the Luding earthquake triggered a noteworthy increase in Coulomb stress along the northern segment of the Moxi Fault. Consequently, the Luding earthquake did not ultimately reduce the seismic hazard within the Xianshuihe fault zone. Thus, greater attention should be directed towards the unruptured section of the Moxi Fault and its adjoining rupture with the background of large earthquakes.

The surface deformation information can effectively reflect the activity status of the magma chamber under the volcano, which is very important for understanding the evolution process of volcanic activity. By capturing deformation anomalies, the volcanic hazard can be assessed, providing insights into the supply, storage, and triggering mechanisms of volcanic magma systems.

According to statistics, there are 14 active volcanoes in China with potential eruption risks. Among them, Tianchi volcano of Changbaishan is considered the largest and most dangerous active volcano within China’s borders. It is located on the northern edge of the Sino-Korean Plate, situated to the east of the Dunhua-Mishan fault at the outermost edge of the Northeast rift system and to the west of the back-arc basin of the Japan Sea. Multiple groups of faults in the NE-SW and NW-SE directions are widely developed in the region. Since 2002, seismic activity in the Tianchi volcano area has gradually increased, with the annual average earthquake frequency rising from dozens to over a hundred times, reaching its peak in 2003 with over a thousand occurrences. However, seismic activity has gradually decreased after 2006. Nevertheless, between 2020 and 2022, two episodes of seismic swarms occurred beneath the Tianchi volcano, with epicenters exhibiting a dispersing pattern gradually spreading from beneath the volcanic vent. This indicates that the Tianchi volcano still retains the potential for eruption.

This study investigates the Tianchi volcano as the research area. It utilizes Sentinel-1A/B images from three orbits, namely ascending and descending passes, and employs advanced techniques including Small Baseline Subset(SBAS)InSAR and Stacking InSAR to retrieve Line of Sight(LOS)surface deformation results of the Tianchi volcano from 2015 to 2022. Additionally, InSAR observations are used as surface constraints, and the geometric distribution of the magma reservoir in Tianchi volcano is inverted using the Mogi point source model. By analyzing the inferred volume change rate of the magma reservoir and integrating it with previously published results obtained from geodetic measurements, the mechanisms underlying the variations in the magma reservoir and the temporal sequence of volcanic activity in Tianchi volcano are explored. The primary conclusions are as follows:

(1)According to the acquired LOS InSAR average deformation rate data from 2015 to 2022, covering the Tianchi volcano, the deformation results from different orbits show good consistency in their distribution. Near the volcano crater, there is an overall trend of deformation, while in areas farther away from the crater, local deformation exists. Over the past seven years of monitoring, there has been a slow subsidence phenomenon near the volcano crater, with a deformation rate of approximately -4mm/a to -2mm/a. By extracting the profile deformation time series from one descending orbit, it is found that the maximum cumulative deformation is about -40mm. The results of the deformation time series indicate that the surface deformation of the Tianchi volcano was relatively small between 2014 and 2017, indicating relatively stable magmatic activity during this period. However, starting in 2018, there has been a certain degree of accelerated deformation, and surface deformation mainly occurs around the volcano crater.

(2)According to the inversion results of the Mogi model, the shallow magma chamber beneath the Tianchi volcano has an estimated depth of approximately 6km, with a volume change rate of -3.3×10⁵m³/a. The geographical location of the magma chamber is situated slightly below and to the west of the Tianchi volcano crater. The inversion results indicate that during the monitoring period, the magma chamber displayed an overall slow contraction. It is speculated that the deformation activity of the magma chamber may be attributed to magma cooling and crystallization processes.

(3)According to the inversion of geodetic measurement data on magma chamber volume changes, during the period from 1995 to 1998, the magma chamber of the Tianchi volcano underwent progressive expansion deformation at a sluggish rate. The Tianchi volcano experienced significant surface uplift deformation from 2002 to 2005. During this period, the magma chamber exhibited a rapid expansion deformation with a fast volume change rate. Starting from 2006, the surface deformation rate weakened, and the volume change rate slowed down. From 2009 to 2011, the inversion of leveling observation data indicated a contraction of the magma chamber volume. Throughout the observation period of this study, the magma chamber continued to exhibit a contraction phenomenon. From 1995 to 2022, the Tianchi volcano underwent a process of magma activity, transitioning from a state of quiescence to perturbation and back to quiescence.

The Haiyuan-Liupanshan tectonic belt is one of the most significant tectonic deformation areas in the northeastern Qinghai-Tibetan plateau with frequent strong earthquakes. It is an important opportunity to study the northeast extension of the Qinghai-Tibetan plateau and an ideal place to study the earthquake breeding process.

The published GPS observations show that the southwest side of the Haiyuan fault may still be undergoing deformation caused by the crustal viscoelastic relaxation effect of the 1920 Haiyuan M8.5 earthquake. And the publicly published leveling data results show local vertical deformation of the crust in the area west of the Liupanshan fault is significant. According to the seismic geological data, there exist historical earthquake rupture gaps in the middle and south sections of the Liupanshan fault and the southeast section of the Xiangshan-Tianjingshan fault in the Haiyuan-Liupanshan structural area, which have the background of strong earthquakes above M7.0. In view of the low spatial resolution of GPS and leveling observations, we need to use high-resolution crustal deformation fields to further study the crustal deformation characteristics of the above regions. Therefore, we further discuss the above issues in combination with InSAR observations.

The Sentinel-1A/B SAR data of two orbits covering the Haiyuan-Liupanshan fault from 2014 to 2020 were processed to obtain the current crustal deformation field in the line-of-sight direction. Furthermore, the high-density regional crustal deformation field was obtained by integrating InSAR and published GPS observations of the horizontal crustal movement velocity field on a time scale of 20 years. By comparing the observations of GPS, leveling and InSAR and high-resolution three-dimensional deformation integrated GPS-InSAR field, the characteristics of crustal deformation and strain field in the region are analyzed and discussed. The main conclusions are as follows:

(1)GPS and InSAR observations show that the post-seismic viscoelastic relaxation effect of the 1920 Haiyuan M8.5 earthquake may still be pronounced on the south side of the Haiyuan fault, but this conclusion is still speculative and needs to be confirmed by further observations;

(2)The high-resolution horizontal deformation field from GPS-InSAR shows that the decrease of the sinistral slip rate of the Haiyuan fault along the fault strike mainly occurs in the Middle East section. In contrast, the decrease of the middle and west sections is not significant, which may be related to the transformation of the left-lateral strike-slip to thrust nappe structure between the Haiyuan fault and the Liupanshan fault.

(3)GPS vertical and leveling observations both show that the vertical crustal deformation characteristics in the middle and south sections of the Liupanshan fault are similar to the vertical deformation of the Longmenshan fault before the Wenchuan earthquake. Considering the similar structural characteristics of the Liupanshan fault and the Longmenshan fault, and combining with the seismic and geological data, we believe that the Liupanshan fault may be in the relatively late stage of the earthquake breeding process. It can also be recognized by the high-resolution horizontal deformation and strain field derived from GPS-InSAR data. According to the fault motion parameters obtained in our study and the existing seismic and geological data, it is estimated that the maximum moment magnitude of an earthquake in the middle-south section of Liupanshan Mountain is approximately 7.5.

(4)The areas with rapid maximum strain accumulation in the study region are mainly concentrated in the vicinity of the Haiyuan fault and the left lateral shear zone between the Haiyuan fault and the Xiangshan-Tianjingshan fault. The dilatation strain rate west of the Liupanshan fault shows prominent compressive deformation characteristics corresponding to the nappe deformation in the Liupanshan tectonic area. The strain rate field in the southeast section of the Xiangshan-Tianjingshan fault is smaller than that of the surrounding area. There is a strain mismatch phenomenon, which may be related to the preparation for strong earthquakes. From the perspective of rotational deformation, the study area presents multiple deformation units, among which counterclockwise rotation corresponds to left-lateral strike-slip deformation(the left-lateral shear belt from the Haiyuan fault to the Xiangshan-Tianjingshan fault). In contrast, clockwise rotation corresponds to right-lateral strike-slip deformation(the right-lateral shear belt in the western margin of Ordos and Longxi block).

The Qinghai-Tibet Plateau has always been one of the areas with frequent strong earthquakes in China. On July 23, 2020, an M_W6.3 earthquake occurred in Nima, Tibet in a half-graben basin of the Yibug Caka-Riganpei Co fault zone in the central Qiangtang block. After the earthquake, many institutions have calculated the focal mechanism solutions based on seismic waves. Although there are differences in the source location and the parameters of the seismic fault, they all show that it is a normal fault earthquake. This is inconsistent with the strike-slip character of the Yibug Caka-Riganpei Co Fault. In addition, this earthquake is another strong earthquake that occurred on Yibug Caka-Riganpei Co Fault after the Gaize M_S6.9 event on January 9, 2008. Therefore, by studying this earthquake, we can better determine the tectonic movement of the seismogenic fault, so it has great significance for understanding the seismogenic mechanism and risk of the central Qiangtang block.
The average elevation in the central Qiangtang is more than 4 800m, the environment is harsh and it is difficult to carry out the field survey of the earthquake. At the same time, GNSS sites near the epicenter are extremely sparse. Therefore, the InSAR technology, which has been successfully applied to several earthquakes in Qinghai-Tibet Plateau, and the Sentinel-1 SAR data, which can be downloaded free of charge, are used to study this earthquake.
Firstly, we obtain the coseismic deformation field based on GAMMA software and select SRTM data with 30m resolution(http://gdex.cr.usgs.gov/gdex/)as the reference DEM. In order to improve the orbit error in interferogram, the precise orbit data provided by ESA(https://qc.sentinel1.eo.esa.int/aux_poeorb/)is used for correction. The adaptive filtering method with filtering function based on local fringe spectrum is used to filter the interferograms, and the filtering windows are set to 128×128 and 32×32, respectively. This iterative filtering window setting from large to small can greatly improve the coherence of the interferogram. Unwrapping phase method uses minimum cost flow(MCF)technology and irregular triangular mesh(TIN). In the ascend and descend InSAR deformation field, we can observe that both deformation trends are basically consistent. The earthquake caused an elliptic settlement area(~12km long and~8km wide)in the basin, and the maximum settlements in line-of-sight direction are -0.298m and -0.238m in the ascend and descend InSAR deformation field, respectively. It can also be observed that the basin has a small amount of horizontal sliding relative to the mountains on both sides. Based on the ascending and descending deformation field, the deformation pattern of the earthquake accords with the main characteristics of normal-fault event, which is consistent with seismological results.
Secondly, taking the focal mechanism solutions published by GCMT and NEIC as initial reference values, the seismic fault parameters are determined based on the elastic half-space dislocation model and InSAR deformation field. Then, according to the linear relationship between the slip and the deformation on the fault plane, SDM method is used to invert the coseismic slip distribution on the fault. In the inversion, since the average Poisson's ratio in Qiangtang is significantly higher than that in the normal crust, the Poisson's ratio is set at 0.29. The results show that: 1)The coseismic slip is dominated by normal dip-slip motion, with small amount of strike-slip component, and the slip is mainly distributed at the depths of 3~12km, with the maximum slip of approximately 1.1m at the depth of 7km. The causative fault did not rupture the surface; 2)The seismic fault is the west branch fault of the Yibug Caka-Riganpei Co Fault, with a strike of ~30°, a dip of ~68°, a slip of ~-73°.
The Yibug Caka-Riganpei Co Fault is still active today, and it is generally a left-lateral strike-slip fault. The Yibug Caka Lake in the epicentral area is a pull-apart basin controlled by the strike-slip fault. The rupture pattern of the Nima earthquake is similar to that of the Gaize M_S6.9 earthquake in 2008, both of which are normal dip-slip caused by accumulation of tensile stress. This is different from the strike-slip character of Yibug Caka-Riganpei Co Fault, indicating that there is extensional stress accumulation in the Yibug Caka-Riganpei Co strike-slip fault and the central part of the Qiangtang block is under an extensional stress regime. Most shallow earthquakes in Qiangtang block occur at the junctures of active faults. Therefore, more attention should be paid to this kind of areas in the future research on seismic risk of Qiangtang block.

A M_S6.4 earthquake occurred on May 21^th, 2021 at Yangbi, Yunnan. In this paper, high resolution InSAR coseismic deformation fields were obtained based on the ascending and descending track of Sentinel-1 SAR images. Based on the InSAR-derived deformation fields, the geometric model of the seismogenic fault was determined according to the aftershock relocation results. Then the fine coseismic slip distribution of the fault plane of Yangbi earthquake was inversed using a distributed sliding inversion method. Finally, the regional strain distribution and the Coulomb stress variation on the surrounding faults caused by coseismic dislocations and viscoelastic relaxation effect after earthquake were calculated, and the seismic risk of the seismogenic structure and the surrounding faults was discussed. The results show that the descending track co-seismic deformation field shows that the NE wall of the seismogenic fault moves close to the satellite, while the SW wall moves far away from the satellite, and the coseismic deformation is symmetrically distributed. The maximum LOS vectors were 8.6cm and 7.9cm, respectively, and the descending track profile showed a coseismic displacement up to 15cm. The fringes on the southwest side of the ascending track interferograms are relatively clear, showing movement close to the satellite, and the maximum LOS deformation magnitude is 5.7cm, while the interference fringes on the northeast side are not clear and the noise is obvious. The fault co-seismic dislocation is mainly of dextral strike-slip with a small amount of normal fault component. The coseismic slip mainly distributes at depths 2~10km, and the coseismic sliding rupture length is about 16km with the maximum slip of approximately 0.46m at a depth 6.5km. The average slip angle is 180° and the inverted magnitude is approximately M_W6.1. The causative fault did not rupture the surface. From the analysis of regional strain distribution and tectonic dynamic background, the Yangbi earthquake occurred in the region where the Sichuan-Yunnan rhomboid block is blocked in its process of SE movement by the South China block and deforms strongly. Combined with the analysis of the geometric occurrence and movement properties of faults, our study suggests that the causative fault of the Yangbi earthquake maybe is a branch of the Weixi-Qiaohou Fault or an unknown fault that is nearly parallel to it on the west side. This earthquake has a significant impact on the Coulomb stress of the Longpan-Qiaohou Fault, Chenghai Fault and Red River Fault in the southwestern Sichuan-Yunnan rhombic block. The Coulomb stress in the northern section of Red River Fault is the most significant. The cumulative Coulomb stress variations of the coseismic and 10 years after the earthquake show that the Coulomb stress variation has increased in the northwestern Yunnan tectonic area. This earthquake is another typical seismic event occurring in the southwest of the Sichuan-Yunnan block after the Lijiang M_S7.0 earthquake in 1996 and the Mojiang M_S5.9 earthquake in 2018. The risk of strong earthquakes in the regional extensional tectonic system in northwest Yunnan and in the north section of the Red River fault zone cannot be ignored.

A M_S6.4 earthquake occurred on January 19^th, 2020 at Jiashi, Xinjiang, this earthquake is another strong earthquake since the Jiashi M_S6~7 earthquake swarm events from 1997 to 2003, and the epicenter was located near the Kalpin nappe in the western part of southern Tianshan. The Kaplin nappe is located in front of southern Tianshan Mountains, which is a thin skinned thrust belt composed of a series of nearly NE-SW thrust nappes under the strong and sustained regenerative orogeny in the Tianshan area. There are some differences in focal positions and fault parameters given by different institutions, therefore in this paper, high resolution InSAR coseismic deformation fields were obtained based on the ascending and descending tracks of Sentinel-1 SAR images to obtain the focal mechanism. The 30m resolution SRTM DEM data is chosen as the external DEM to eliminate the phases caused by topography, the robust Goldstein filtering is applied for phase smoothing, and the Delaunay minimum cost flow method is used for phase unwrapping. The variation range of interference fringes shows that the east-west span of the earthquake deformation field is about 40km, and that of the north-south direction is about 20km, the displacement results show that the maximum uplift displacement is 5.9cm and the maximum subsidence is 3.7cm along the LOS direction of the ascending data, the maximum uplift displacement is 6.4cm and the maximum subsidence is 2cm along the LOS direction of the descending data. And then the InSAR-derived deformation fields are used to obtain the seismogenic mechanism of this earthquake, and to improve the computational efficiency, the quadtree segmentation method is used to desample the original high-resolution InSAR observations before inversion. The coseismic slip distribution of the causative fault was inversed using a uniform sliding inversion method based on a Bayesian approach, and then the fine slip distribution of the fault plane of Jiashi earthquake was inversed using the distributed slip inversion method based on the constrained least squares. It should be noted that the fault plane is set as the shovel shape according to the geometric relationship between the seismogenic fault parameters inverted by uniform sliding and the exposed position of the Kapling Fault on the surface during the distributed slip inversion. According to the difference between the observed and simulated values, it can be seen that the residual error of the inversion model is small, indicating the reliability of the inversion result. The final result shows that the epicenter is located at 39.9°N, 77.28°E and the strike and dip angle of the seismogenic fault is 276° and 10.7°, respectively, the maximum dip slip and strike slip of fault plane is about 0.29m and 0.03m, respectively, which are located at the depth of about 5km underground. The cumulative coseismic moment is 1.73×10¹⁸N·m from InSAR inversion, which is equal to the moment magnitude of M_W6.1 and the Kalpin Fault is supposed to be the causative fault. Then, regional GPS-derived surface strain rate, tectonic dynamic background, and regional deep and shallow structures were comprehensively analyzed. The results show that the Jiashi M_S6.4 earthquake is a typical thrust event that occurred in the thrust nappe of the southern Tianshan. The 2020 Jiashi event and the 1997—2003 Jiashi M6~7 earthquakes swarm are the results of rupture of many faults with different scales and properties. And these events are all controlled by the thrust nappe of southern Tianshan.

Using a more realistic model of multi-layered viscoelastic media, and considering the effects of the coseismic dislocation and the postseismic viscoelastic relaxation caused by the 34 great earthquakes occurring along the eastern boundary of the Sichuan-Yunnan block since 1480 and the interseismic stress accumulation caused by the tectonic loading generated by plate motions which were modeled by introducing "virtual negative displacements" along the major fault segment in the region under study, we calculated the evolution of the Coulomb stress change in each fault plane of 18 major fault segments along the eastern boundary caused by the coseismic, postseismic and interseismic effects. We studied the interactions of the Xianshuihe, Anninghe, Zemuhe and Xiaojiang fault zones on the eastern boundary of the Sichuan-Yunnan block. By evaluating if the previous earthquake could bring another earthquake closer to or farther from failure, we analyzed the interactions of the earthquakes which occurred in the different segments in the same fault zone, or in the different fault zones respectively. And further based on the calculation results of the Coulomb stress change on the fault planes, we analyzed the seismic hazard of each fault segment.The results show that the previous earthquake may trigger another earthquake which can occur in the same fault zone or in the different fault zone. And the calculation results on the evolution of the cumulative Coulomb stress change in the each fault segment show that, the Coulomb stress increases significantly in the middle section and the Moxi segment of the Xianshuihe fault zone, the Mianning-Xichang segment of the Anninghe fault zone, the Qiaojia-dongchuan segment and the Jianshui segment of the Xiaojiang fault zone, and the seismic hazard in these fault segments is worthy paying attention to.

Ashikule Basin is located in the‘arc’intersection of NE-trending Altyn Tagh Fault and NW-trending Kangxiwar Fault, in which there are frequent tectonic activities, and more than 10 volcanoes are developed, including Ashi volcano, the latest active volcano in the Ashikule volcanic group. This paper conducts a detailed study on the Ashi volcano from four aspects, including volcanic geology, lava and phenocryst composition, microstructure features and geothermobarometer. The results show that Ashi volcano consists of volcanic cone and lava flow, and specifically the body of the cone is built by early scoria cone and later spatter cone and the lava flow with the area of about 33km² is divided into four flow units. The lavas belong to shoshonite, trachyandesite in composition, and show porphyritic texture under microscope. The main phenocrysts are plagioclase(major in andesine)and pyroxene(including augite, bronzite and hypersthenes); The matrix is glassy, cryptocrystalline, and phaneritic, part of which has lots of feldspar and pyroxene microlites. The phenocryst-liquid equilibrium temperature is 1 104～1 194℃, and the equilibrium pressure is 570～980MPa, indicating that the depth of the magma chamber is about 18.92～32.29km.

The Ashikule volcanic group is located in the Ashikule Basin,which is situated about 250km south of Yutian County,Xinjiang. Ashikule volcanic group consists of more than 10 large volcanoes and dozens of small volcanoes. Its present-day activity is unknown due to the extremely high altitude and inclement weather. Based on Envisat ASAR and ALOS PALSAR images,we obtain the land surface deformation field(2003-2010)by using stacking InSAR(Interferometric Synthetic Aperture Radar)and SBAS-InSAR(Small BAseline Subsets-Interferometric Synthetic Aperture Radar)techniques. We also analyze the volcanic activity based on the InSAR-derived deformation field. Our results show that the deformation of Ashikule volcanic group was not obvious before the 2008 Yutian earthquake(2003-2007).However,it showed a large-scale movement towards satellite after the 2008 Yutian earthquake(2008-2010)with largest accumulated displacement of 1cm. We speculate the large-scale movement had nothing to do with volcanic activity,but it was a result of stress adjustment caused by the 2008 Yutian earthquake. Nevertheless,the northmost end of the coseismic rupture showed movement towards east,and also deflated very much with accumulated subsidence of 6cm.

The paper firstly introduces the research status of using thermal infrared remote sensing technology to monitor volcanic activity around the world,then reviews the principle of thermal infrared remote sensing technology.Meanwhile,the feasibility of monitoring volcanic activity using satellite thermal infrared remote sensing technology is analyzed.Moreover,we take the Changbaishan Tianchi volcano as an example.Firstly,land surface temperature distribution maps of Changbaishan Tianchi volcano are retrieved from Landsat TM/ETM images and ASTER images taken from 1999 to 2008.Then,to reduce the effect of different surface cover,we choose three types of the surface cover,i.e.vegetation(forest), mixture of soil and vegetation(short grasses),and bare rock.For each type of surface covers,the average daily temperature obtained from Tianchi Weather Station is deducted in order to reduce the effect of weather change.Finally,we obtain the annual surface temperature variation of the study area, which is believed to be caused by volcanic activity in the magma chamber.Our results indicate that the temperature of the study area increased with an intermittent tendency during 1999 to 2005,but dropped after 2005,and then maintained a stable tendency during 2006 to 2008.Such tendency of annual temperature variation caused by volcanic activity is consistent with the results from other different observation methods,e.g.seismic monitoring,ground deformation from GPS measurement,ratio of He isotope change from geochemistry monitoring.The results imply that it is of great potential to use the satellite thermal infrared remote sensing technology in monitoring volcanic activity.So the satellite thermal infrared remote sensing technology can be used as a routine means to monitor volcanic activity.