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.

Coseismic surface rupture length is one of the critical parameters for estimating the moment magnitude based on the empirical relationships and later used in assessing the potential seismic risk of a region. On 22 May 2021, the M_W7.4 Madoi earthquake occurred in the northeastern part of the Tibetan plateau(Madoi County in Qinghai Province, China)and ruptured the poorly known Jiangcuo Fault along the extension line of the southeastern branch of the Kunlun Fault. We began our data acquisition using aerial photogrammetry by UAV three days after the earthquake. Between 24 May and 15 June 2021, more than 40000 high-resolution low-altitude aerial photos were acquired covering a total length of 180km along the surface rupture. Based on detailed field investigations, combined with a fine interpretation of sUAV-derived orthophotos and high-resolution DEMs, we determined a total length of~158km of the coseismic surface rupture extending to the eastern end at 99.270°E, which is basically consistent with the position given by previous geophysical methods. Although the extending segment is located beyond the end of the continuous surface rupture trace near Xuema Township, it should be included in the calculation of the length of the surface rupture as part of the tectonic surface rupture. The surface rupture is segmented into four sections, named from west to east: the Eling Lake, Yematan, Yellow River, Jiangcuo branch sections. Additionally, to the east of Dongcaoa’long Lake, we mapped semi-circular arc-shaped continuous tension-shear fractures in the dune area with a short gap(~3km)connecting to the east of the Jiangcuo branch. The surface ruptures along the southeastern Youyunxiang segment also sporadically appear in several sites, locally relatively continuous, covered by the sand dune with vertical displacements of up to 30cm. After passing through the dunes, the surface rupture of the Youyunxiang segment began to spread widely, extending continuously with a strike of nearly east-west. However, it should be noted that the rupture lengths of the Youyunxiang segment and other branches are not counted in the total earthquake rupture length. By comparing the current research results, we believe that the critical factors causing the significant differences of the measured length of coseismic surface ruptures would depend on: 1)more extensive and detailed field investigations combined with a fine interpretation of high-resolution images; 2)avoidance of repeated calculation of superimposed sections on both sides of the complex geometrical area. In this study, combined with the fine interpretation of high-precision image data, many surface rupture traces in the dunes of the Youyunxiang segment were identified(verified and confirmed by field inspection)and more continuous surface rupture segments on the F1 fault, which is difficult to reach by human beings, were discovered, also highlights the important role of digital photogrammetry in the study of active tectonics. The studies of the strong historical earthquakes around the Bayan Har block show that the coseismic surface rupture length is larger than that estimated by the empirical relationships. Further research thus is highly necessary to uncover its mechanism and indicative significance.

Earthquake surface ruptures are the key to understand deformation pattern of continental crust and rupture behavior of tectonic earthquake, and the criteria to directly define the active fault avoidance zone. Traditionally, surface fissures away from the main rupture fault are usually regarded as the result triggered by strong ground motion. In recent years, the earth observation technology of remote sensing with centimeter accuracy provides rich necessary data for fine features of co-seismic surface fractures and fissures. More and more earthquake researches, such as the 2019 M_W7.3 Ridgecrest earthquake, the 2016 M_W7 Kumamoto earthquake, the 2020 M_W6.5 Monte Cristo Range earthquake, suggest that we might miss off-fault fissures associated with tectonic interactions during the seismic rupture process, if they are simply attributed to effect of strong ground motion. Such distribution pattern of co-seismic surface displacement may not be isolated, it encourages us to examine the possible contribution of other similar events. The 22 May 2021 M_W7.4 Madoi earthquake in Qinghai Province, China ruptured the Jiangcuo Fault which is the extension line of the southeastern branch of the Kunlun Fault, and caused the collapse of the Yematan bridge and the Cangmahe bridge in Madoi County. The surface rupture in the 2021Madoi earthquake includes dominantly ~158km of left-lateral rupture, which provides an important chance for understanding the complex rupture system.
The high-resolution UAV images and field mapping provide valuable support to identify more detailed and tiny co-seismic surface deformation. New 3 to 7cm per pixel resolution images covering the major surface rupture zone were collected by two unmanned aerial vehicles (UAV) in the first months after the earthquake. We produced digital orthophoto maps (DOM), and digital elevation models (DEM) with the highest accuracy based on the Agisoft PhotoScan^TM and ArcGIS software. Thus, the appearance of post-earthquake surface displacement was hardly damaged by rain or animals, and well preserved in our UAV images, such as fractures with small displacement or faint fissures. These DOM and DEM data with centimeter resolution fastidiously detailed rich details of surface ruptures, which have been often easily overlooked or difficult to detect in the past or on low-resolution images. In addition, two large-scale dense field investigation data were gathered respectively the first and fifth months after the earthquake. Based on a lot of firsthand materials, a comprehensive dataset of surface features associated with co-seismic displacement was built, which includes four levels: main and secondary tectonic ruptures, delphic fissures, and beaded liquefaction belts or swath subsidence due to strong ground motion. Using our novel dataset, a complex distributed pattern presents along the fault guiding the 158km co-seismic surface ruptures along its strike-direction. The cumulative length of all surface ruptures reaches 310km. Surface ruptures of the M_W7.4 Madoi earthquake fully show the diversity of geometric discontinuities and geometric complexity of the Jiangcuo Fault. This is reflected in the four most conspicuous aspects: direction rotation, tail divarication, fault step, and sharp change of rupture widths.
We noticed that the rupture zone width changed sharply along with its strike or geometric complexity. Near the east of Yematan, on-fault ruptures are arranged in ten to several hundred meters. Besides clearly defined surface ruptures on the main fault, many fractures near the Dongo section and two rupture endpoints are mainly along secondary faulting crossing the main fault or its subparallel branches. Lengths of fracture zones along two Y-shaped branches at two endpoints are about 20km. At the rupture endpoints, the fractures away from the main rupture zone are about 5km. Some authors suggested the segment between the Dongcao along lake and Zadegongma was a “rupture gap”. In our field investigation, some faint fractures and fissures were locally observed in this segment, and these co-seismic displacement traces were also faintly visible on the UAV images.
It is also worth noting that near the epicenter, Dongo, and Huanghexiang, a certain amount of off-fault surface fissures appear locally with steady strike, good stretch, and en echelon pattern. Some fissures near meanders of the Yellow River, often appear with beaded liquefaction belts or swath subsidences. In cases like that, fissure strikes are, in the main, orthogonal to the river. Distribution pattern of these fissures is different from usual gravity fissures or collapses. But they can’t be identified as tectonic ruptures because clear displacement marks are always absent with off-fault fissures. Therefore, it is difficult to determine the mechanism of off-fault co-seismic surface fissures. Some research results suggested, that during the process of a strong earthquake, a sudden slip of the rupturing fault can trigger strain response of surrounding rocks or previous compliant faults, and result in triggering surface fractures or fissures.
Because of regional tectonic backgrounds, deep-seated physical environments, and site conditions(such as lithology and overburden thickness), the pattern and physicalcause of co-seismic surface ruptures vary based on different events. Focal mechanisms of the mainshock and most aftershocks indicate a near east-west striking fault with a slight dip-slip, but focal mechanisms of two M_S≥4.0 aftershocks show a thrust slip occurring near the east of the rupture zone. On the 1︰250000 regional geological map, the Jiangcuo Fault is oblique with the Madoi-Gande Fault and the Xizangdagou-Cangmahe Fault at wide angles, and with several branches near the epicenter and the west endpoint at small angles. Put together the surface fissure distribution pattern, source parameters of aftershocks and the regional geological map, we would like to suggest that besides triggered slip of several subparallel or oblique branches with the Jiangcuo Fault, inheritance faulting of pre-existing faults may promote the development of off-fault surface fissures of the 2021Madoi earthquake. Why there are many off-fault distributed surface fissures with patterns different from the gravity fissures still needs further investigation. The fine expression of the distributed surface fractures can contribute to fully understanding the mechanism of the seismic rupture process, and effectively address seismic resistance requirements of major construction projects in similar tectonic contexts in the world.

2~4 days before the Minxian-Zhangxian M_S6.6 earthquake on July 22, 2013, short-term and impending anomalies dominated by normal fault type abrupt change were observed at mobile cross-fault short-leveling sites, Sidian, Maoyugou and Majietan, within 37~70km from the epicenter, especially at the Sidian site, where the amplitude of the anomaly reached up to 5.5mm. In this paper, based on the analysis of cross-fault short-leveling observations in the western Qinling Mountains tectonic area, where the above three sites are located, and the experimental results of structural mechanics for the existence of meta-instable stress state before fault instability, the anomaly mechanism is discussed, combined with the information of GPS continuous observation and small earthquakes activities. The results show that: 1)Several days before the earthquake, obvious “changes” in the micro-dynamic variation magnitude and characteristics of fault activities were observed, which revealed that the regional stress had changed. New synchronous anomalies occurred at Sidian, Maoyugou and Majietan sites, especially at Sidian site where the anomaly was large in amplitude, and the number and magnitude of the anomalies increased obviously; Moreover, the dynamic distribution of anomalies of the observational curves showed an obvious change process of the characteristics of tectonic fault activities. In the western Qinling tectonic area, the change was mainly dominated by reverse faulting, but this reverse fault type change was not dominant several months before the earthquake, and till a few days before the earthquake, the normal fault type variation was absolutely dominant, which is contrary to the long-term background of the reverse fault favorable for stress concentration in this tectonic area; In addition, temporal variation of trend accumulation rate, which reflects the feature and magnitude of stress-strain accumulation, showed the accumulation firstly slowing down in several months and turning obviously in several days before the earthquake. 2)Obvious anomaly variation was observed at the sites near the earthquake region several days before the earthquake, the crustal stress evolved from “regional change” to “localized enhancement”. During the four observational periods before the earthquake, it was observed that the cross-fault anomalies were gradually concentrated to the local tectonic region where the earthquake occurred, also the grey relativity index which reflects the general trend of fault activities displayed a larger turning magnitude in this local tectonic region; Next, the local fault segment mostly near the epicenter not only maintained the reverse fault type change consistent with the earthquake dislocation, significant accelerating anomalies were also observed at Majietan site, which may be the relatively strong stress concentration position. The auxiliary data of continuous GPS observation and small earthquake activities were also of some supporting significance to above phenomena. The comprehensive analysis shows that the temporal and spatial evolution process of fault activities and anomalies obtained from the cross-fault short-leveling observation in the western Qinling tectonic area before the strong earthquake accorded with the characteristics of meta-stable(deviating from linear stage)-meta-instable state revealed by the structural mechanics experiment.

After an earthquake, earthquake emergency response and rescue are important ways to mitigate earthquake-induced losses. Various earthquake emergency maps can provide effective references and guidance to those actions. Currently, related studies include the investigation on symbols of emergency maps, remote sensing emergency mapping and GIS-based mapping methods. However, the existing studies overlook the characteristics of rapidity, dynamicity and variety of presentation methods in making earthquake emergency maps. In this paper, a map template matching method is used to quickly make earthquake emergency maps considering their characteristics. We take investigations on the service objects(users)of the earthquake emergency maps to understand the needs of making earthquake emergency maps. The audience theory in mass media field and map information transmission theory are adopted to classify the users of the earthquake emergency maps into four categories: earthquake emergency commanders, technical staffs for decision-making, earthquake emergency rescuers, and the public. The components of different types of users are described and then their diverse demands in earthquake emergency maps are analyzed, such as the needs of on-field disaster information maps, earthquake information maps, physical geography and social economic maps. Following those needs, we introduce the representation methods of the earthquake emergency maps according to their formats(vector or raster)and contents, such as point symbolization method, kilometer grid method, line symbolization method and range method. Then, we study the rapid plotting method of earthquake emergency map based on map template matching method. The core steps of the method include: 1)before earthquake, the templates of different earthquake emergency maps are designed, prepared and connect the earthquake emergency features with their related spatial database. The map layout and map elements are stored in the templates. 2)After earthquake, the earthquake emergency features will be generated from seismic models(such as attenuation model of earthquake magnitude and seismic intensity)or the information obtained from field investigation. 3)Corresponding earthquake emergency map template is selected in accordance with the generated seismic features. And the features are used to update related features inside the selected template. 4)Minor adjustments are made such as to the map scale and some map annotations to finally generate the formal earthquake emergency map. Architecture of template system of the earthquake emergency maps is designed, including map user level, map template level, template layer level and map element level. Regrading to the architecture, the general map template of earthquake emergency is presented which includes four main regions: title region, main picture region, auxiliary region and annotation region. The main picture region is the essential, which lays geographic background maps and earthquake emergency features. Finally, an earthquake emergency mapping system is developed. Based on the system, a case study is presented, which demonstrates making a simulated seismic intensity influence map. From three aspects, the case presents the application of the template-matching method including: generating earthquake emergency features, substituting the features inside the template with the generated features, and revising map annotations. Therefore, the map template matching method is verified so that it can be used to quickly generate various earthquake emergency maps.

Coulomb stress change on active faults is critical for seismic hazard analysis and has been widely used at home and abroad. The Sichuan-Yunnan region is one of the most tectonically and seismically active regions in Mainland China, considering some highly-populated cities and the historical earthquake records in this region, stress evolution and seismic hazard on these active faults capture much attention.
    From the physical principal, the occurrence of earthquakes will not only cause stress drop and strain energy release on the seismogenic faults, but also transfer stress to the surrounding faults, hence alter the shear and normal stress on the surrounding faults that may delay, hasten or even trigger subsequent earthquakes. Previously, most studies focus on the coseismic Coulomb stress change according to the elastic dislocation model. However, the gradually plentiful observation data attest to the importance of postseismic viscoelastic relaxation effect during the analysis of seismic interactions, stress evolution along faults and the cumulative effect on the longer time scale of the surrounding fault zone. In this paper, in order to assess the seismic hazard in Sichuan-Yunnan region, based on the elastic dislocation theory and the stratified viscoelastic model, we employ the PSGRN/PSCMP program to calculate the cumulative Coulomb stress change on the main boundary faults and in inner blocks in this region, by combining the influence of coseismic dislocations of the M≥7.0 historical strong earthquakes since the Yongsheng M7.8 earthquake in 1515 in Sichuan-Yunnan region and M≥8.0 events in the neighboring area, and the postseismic viscoelastic relaxation effect of the lower crust and upper mantle.
    The results show that the Coulomb stress change increases significantly in the south section of the Xianshuihe Fault, the Anninghe Fault, the northern section of the Xiaojiang Fault, the southern section of the Longmen Shan Fault, the intersection of the Chuxiong-Jianshui Fault and the Xiaojiang Fault, and the Shawan section of the Litang Fault, in which the cumulative Coulomb stress change exceeds 0.1MPa. The assuming different friction coefficient has little effect on the stress change, as for the strike-slip dominated faults, the shear stress change is much larger than the normal stress change, and the shear stress change is the main factor controlling the Coulomb stress change on the fault plane. Meanwhile, we compare the Coulomb stress change in the 10km and 15km depths, and find that for most faults, the results are slightly different. Additionally, based on the existing focal mechanism solutions, we add the focal mechanism solutions of the 5 675 small-medium earthquakes(2.5≤M≤4.9)in Sichuan-Yunnan region from January 2009 to July 2019, and invert the directions of the three principal stresses and the stress shape factor in 0.1°×0.1° grid points; by combining the grid search method, we compare the inverted stress tensors with that from the actual seismic data, and further obtain the optimal stress tensors. Then, we project the stress tensors on the two inverted nodal planes separately, and select the maximum Coulomb stress change to represent the stress change at the node. The results show that the cumulative Coulomb stress change increase in the triple-junction of Sichuan-Yunnan-Tibet region is also significant, and the stress change exceeds 0.1MPa.
    Comprehensive analysis of the Coulomb stress change, seismic gaps and seismicity parameters suggest that more attention should be paid to the Anninghe Fault, the northern section of the Xiaojiang Fault, the south section of the Xianshuihe Fault, the southern section of the Longmen Shan Fault and the triple-junction of the Sichuan-Yunnan-Tibet region. These results provide a basis for future seismic hazard analysis in the Sichuan-Yunnan region.

The bedrock scarps are believed to have recorded the continuous information on displacement accumulation and sequence of large earthquakes. The occurrence timing of large earthquakes is believed to be correlated positively with the exposure duration of bedrock fault surfaces. Accordingly, cosmogenic nuclides concentration determined for the bedrock footwall can offer their times, ages, and slip over long time. In general, multiple sites of fault scarps along one or even more faults are selected to carry out cosmogenic nuclide dating in an attempt to derive the temporal and spatial pattern of fault activity. This may contribute to explore whether earthquake occurrence exhibits any regularity and predict the timing and magnitude of strong earthquakes in the near future. Cosmogenic nuclide ³⁶ Cl dating is widely applied to fault scarp of limestone, and the height of fault scarp can reach as high as 15~20m. It is strongly suggested to make sure the bedrock scarp is exhumed by large earthquake events instead of geomorphic processes, based on field observation, and data acquired by terrestrial LiDAR and ground penetration radar (GPR). In addition, it is better for the fault surface to be straight and fresh with striations indicating recent fault movement. A series of bedrock samples are collected from the footwall in parallel to the direction of fault movement both above and below the colluvium, and each of them is~15cm long,~10cm wide, and~3cm thick. The concentrations of both cosmogenic nuclide ³⁶ Cl and REE-Y determined from these samples vary with the heights in parallel to fault scarps. Accordingly, we identify the times of past large earthquakes, model the profile of ³⁶ Cl concentration to seek the most realistic one, and determine the ages and slip of each earthquake event with the errors. In general, the errors for the numbers, ages, and slips of past earthquake events are ±1-2, no more than ±0.5-1.0ka, and ±0.25m, respectively.

It is of great significance to determine the factors and causes that affect the recurrence of major earthquakes. This paper introduces the influence of strong earthquake on the recurrence of major earthquakes according to elastic rebound theory, and then proposes to calculate the impact time Δt respectively from the effect of strong earthquakes on the same and surrounding faults on the major earthquake recurrence by using seismic moment release rate method and Coulomb stress change. In this paper, we studied the change amount of major earthquake recurrence by taking four earthquakes with magnitude greater than 6.5 occurring at different fracture sections of the Xianshuhe fault zone as an example, they occurred on Daofu, Changcu, Zhuwo Fault, respectively. We used seismic moment rate method to calculate the impact time Δt of strong earthquake on the recurrence of major earthquakes on the Daofu-Qianning Fault. We further discussed the effect of the Coulomb stress change due to the interaction between faults on the recurrence of subsequent major earthquakes. The co-seismic and post-seismic Coulomb stress changes caused by strong earthquake on the surrounding faults on the Ganzi-Luhuo Fault are calculated. With the fault interaction considered, the importance of the interaction between faults in the middle-north section of the Xianshuihe fault zone to change the recurrence of large earthquakes is retested and evaluated. The results indicate that the two strong earthquakes occurring along Xianshuihe Fault in 1904(M=7.0) and 1981(M=6.9) resulted in a delay of 80 years and 45 years of major earthquake recurrence on the Daofu-Qianning Fault respectively, and the M7.3 earthquake in 1923 and the M6.8 earthquake in 1967 resulted in an advance of 35 years of major earthquake recurrence on the Ganzi-Luhuo Fault.

China is the country with the challenge of severe earthquake disaster. In order to mitigate the disaster and save lives, emergency response and rescue work after an earthquake are deployed and led by the Chinese governments at all level, the effectiveness of which has been proved. In such work, how to quickly evaluate the seismic intensity in meizoseismal area is a crucial issue at the early period after the earthquake. It is the foundation to estimate the disaster losses and decide the scale of rescue teams and materials. However, at the early period only a few physical parameters of the earthquake can be acquired and some of them may even be inaccurate.
An evaluation model of seismic intensity in meizoseismal area is investigated and presented by statistic method in this study. After an earthquake there are four authoritative parameters officially released by China Earthquake Administration generally within ten minutes:earthquake magnitude (M_S), focal depth, latitude and longitude position, and the occurrence time. They are good candidate input parameters of the evaluation model. We collect the information of 215 historical earthquake occurring in China from 1966 to 2013, including:The four parameters and the seismic intensity in meizoseismal area. Through statistical analysis we find the seismic intensity in meizoseismal area has high correlation with the earthquake magnitude (M_S) and the focal depth and then select them as the formal input parameters. After further investigation a generalized linear model is built to fit the relationship between the seismic intensity in meizoseismal area, earthquake magnitude (M_S) and the focal depth.
The effectiveness of the model is validated by the Sig value and F value from theoretic perspective. The validation also includes the application of the model in real earthquakes occurring from 2014 to 2017. After the earthquakes, the seismic intensities in meizoseismal area have been quickly estimated and used in the command of national earthquake disaster emergency relief. The applications in real earthquakes get good results.
Finally, the robustness of the model is analyzed. We respectively verify the influences of the earthquake magnitude (M_S) and the focal depth and find the seismic intensity in meizoseismal area is more sensitive to the earthquake magnitude. Under the condition of the same focal depth, when the change of the earthquake magnitude is up to 0.5, the change of the seismic intensity will reach to 1. However, in order to cause same change of the seismic intensity, the difference of the focal depth will be 10 kilometers. Basically, these changes derived from the model meet the situation of historical earthquakes.

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.

After an earthquake, earthquake emergency response and rescue is one of the effective ways to reduce casualties from the earthquake. Earthquake emergency disaster information is one of crucial factors to effectively guide the rescue work. However, there is a "black box effect" on the emergency disaster information acquisition after an earthquake, which means real-time earthquake disaster information is insufficient. Hazard estimates are usually used as a substitute for the real-time disaster information in the "black box" period. However, it is subject to the accuracy and speed of the estimation.
The development of the km grid technology provides good prospect to solve this problem. The paper suggests to develop earthquake disaster information pre-estimation data with the support of the km grid technology. The definition and source of the pre-estimation data are introduced and its possibility in improving the estimation speed and accuracy are analyzed theoretically.
Then, we elaborate the calculation model of the pre-estimation data. The framework of the model includes disaster-bearing body data, disaster-causing factors used in calculation and calculation formula. The disaster-bearing body data in km grid format are introduced, including population data in km grid format and building data in km grid format. Then the four elements of the earthquake(earthquake occurrence time, earthquake location, earthquake magnitude and focal depth)are selected as disaster-causing factors for calculation. Map algebra method is used to realize the calculation model in which calculation parameters are associated with base map in the km grid format. So the pre-estimation data are developed by python and ArcGIS, which includes building damage dataset(100 layers), death toll dataset(10 layers)and direct economic loss dataset(5 layers).
Finally, the pre-estimation data based method for earthquake emergency disaster information estimation is presented. With the support of this method, two real earthquake cases are used to validate the effect of the pre-estimation data. The validation results show the pre-estimation data can not only significantly improve the speed of the estimation but also greatly improve the accuracy of the estimation. Another good result is found in the validation process that with the support of the pre-estimation data, the estimated result can display the spatial distribution of the disaster information, which will effectively aid earthquake emergency response and rescues.

The earthquake disaster rapid assessment(EDRA)is the core technical support for the post-earthquake emergency response. At present, with the popularization of high-precision population, social and economic data, most of the subordinate units of China Earthquake Administration(CEA)have heightened the precision of hazard bearing body data used in EDRA from the original county-level precision to the 30″×30″ precision. However, while the precision of fundamental data has been heightened, no efforts have been made to improve the main algorithms and the technical process of EDRA. It turns out that the assessment has become more accurate, but the problems of the time-consuming process(10-20 minutes, probably 20 minutes or more in great earthquakes)and the low-precision losses distributions that exposed in EDRA supported by county-level precision data remain unresolved.This paper introduces the high-precision(30″×30″)hazard bearing body data, and describes the principle of EDRA and its implementation under the support of county-level precision data at first. Then the paper elaborates the principle of improving EDRA's data foundation using high-precision hazard bearing body data, the principle of improving the computation efficiency and persisting the data precision in the assessment process by means of the cell-to-cell grid algebraic operation, and the method for improving the assessment speed through the segmentation and reorganization of the technical process of EDRA.It is validated that through the improvements, the EDRA has become more accurate and much less time-consuming(less than 1 minute), and is able to output high-precision(30″×30″)distributions of seismic losses. The high-precision hazard bearing body data of wide range are the simulated data but not the survey data. Though the data have been simulated based on the census data, there is still a gap between their accuracy and the real situation. Further research and optimization on the data are needed.

China is a country prone to serious earthquake disaster. After an earthquake, earthquake emergency and rescue are very important for the disaster relief, which is also one of three earthquake disaster mitigation jobs led by China Earthquake Administration. In earthquake emergency fields, earthquake preplans and GIS-based earthquake emergency command systems are the main researches and work. How to increase the intelligence and pertinence of the systems and preplans is an important and difficult issue in this area. Earthquake emergency decision-making knowledge provides a possible solution method. The modeling of earthquake emergency decision-making knowledge is the foundation for its use.
We analyze the semantic need of earthquake emergency decision-making knowledge modeling. From the perspective of geospatial knowledge modeling, the earthquake emergency knowledge modeling primitives are put forward, which are adapted from geospatial knowledge modeling primitives. Using geo-ontology as the foundation, the earthquake emergency knowledge modeling primitives include: abstract geospatial modeling primitives, geographic modeling primitives and earthquake emergency field modeling primitives.
A framework model for the earthquake emergency knowledge is proposed and according to the knowledge granularity the framework is divided into the earthquake emergency basic knowledge level, earthquake emergency rule knowledge level and earthquake emergency procedural knowledge level. Then the modeling of the earthquake emergency rule knowledge is discussed, which is composed of rule conditions and rule actions. Meanwhile, the modeling of the earthquake emergency procedural knowledge is introduced based on workflow method and consists of work nodes, control nodes and data nodes.
Finally, Suzhou intelligent earthquake emergency decision-making assisting system is developed, in which several earthquake emergency decision-making knowledge are used. The protégé and ArcEngine software packages are used to realize the earthquake emergency knowledge modeling and application. Through the application system, the usage of framework model is demonstrated.

Earthquake is one of most serious natural disasters in China. In order to effectively mitigate earthquake disaster, three catalogues of jobs have been done under the leadership of China Earthquake Administration. Earthquake emergency is one of such important jobs, which could save life and reduce disaster damage. Earthquake emergency preplan plays a key role in this work, and provides foundation for disaster rescue. Although the emergency preplans get great achievements in many earthquake disaster reliefs, they also show some drawbacks in the practical applications.
In this paper, we analyze the characteristics of Chinese earthquake emergency preplans and find that the framework of emergency preplans is clear, but the provisions on emergency operations are macroscopical and not easy to use; the structures of the emergency preplans are generically similar in the whole country and lack of pertinence to specific disaster areas or professional industries; the connections between earthquake disaster emergency preplans and other disaster emergency preplans are weak; the dynamic managements of the preplans need to be enhanced.
In order to complement the emergency preplans, earthquake emergency response disposal scheme is discussed in this paper, which is an emergency disposal work plan for detailed emergency events after an earthquake from technical perspective and aims at directing earthquake emergency response. The relationships between the emergency preplans and the disposal schemes are introduced. The core difference between them is in that a preplan focuses mainly on who should respond to the emergency event, while a disposal scheme is more concerned about how to cope with the emergency event.
We also present the components of the disposal schemes, which include disposal scheme framework, emergency decision-making knowledge and supported information platforms. Then the work principle of the disposal schemes is described based on these components. In this principle, earthquake emergency decision-making knowledge is used to amend the disposal scheme framework to generate the emergency disposal scheme with the support of information technologies. Within the disposal schemes, three kinds of the disposal countermeasures, namely, descriptive emergency countermeasures, the countermeasures from earthquake emergency professional models and the countermeasures from GIS and RS technical platforms are introduced.
Taking urban level as an example, the urban disposal scheme framework is depicted. It is composed of five parts: geographic environment in disaster area, earthquake information, estimated disaster information, emergency countermeasures and other related countermeasures. Then the components of the decision-making knowledge are introduced. The knowledge representations result from comprehensive processing of various information related to earthquake emergency response and rescue.
This paper lays the foundation for the earthquake emergency response disposal scheme generation and application, which helps to solve the problems of the earthquake emergency preplans. In future, the detailed implementation and application methods of earthquake emergency decision-making knowledge will be studied and used to realize the computer-aided generation of the disposal schemes.

The hazard grade assessment,which simply and clearly reveals how big the damage is,is an important part of emergency response and rescue work after disaster. Upon collection and sorting out of the data on Asian natural disasters occurring between 1900 and 2011,this paper studies the method of classifying those disasters. After discussing the definition of catastrophe and that of earthquake-affected population and exploring the basis on which catastrophe could be classified,this paper comes up with a formula,in which the logarithms of three factors,death toll,direct economic loss and quake-affected population,are summed up. Then,Asian catastrophes are classified by the formula. The calculation based on the formula shows that the results of 54 of all the disasters are above 10.0,102 above 9.0 and 178 above 8.0.After repeated comparison with data from several other disaster databases,it is concluded that the result achieved by the formula of the disaster which is generally considered as a catastrophe,is above 8.0.Therefore,a disaster with a result above 8.0 is defined as a catastrophe. The formula mentioned above in this paper is simple and convenient,and is suitable for making a comparison of the damage caused by the disasters of different types in different regions in Asia.