Based on the analysis and processing of field mobile observation data, soil gas Rn and CO₂ degassing characteristics in the main fault zones of Xiong'an New Area(XNA)and its effects on the regional environment was preliminarily studied. Repeated observations of soil gas concentrations and fluxes in 2020 and 2021 for the seven measurement lines on the buried faults show that strong degassing characteristics exist in the main fault zones of XNA.
The range of variation of the mean soil gas Rn fluxes for each profile is from 71.44 to 335.35mBq/m²·s, and the range of variation of the mean CO₂ fluxes is from 25.96 to 78.23g/m²·d; the range of variation of the mean Rn concentration intensity is from 0.91 to 2.30, and the range of variation of the mean CO₂ concentration intensity is from 1.13 to 2.61, which are comparable to the degassing intensity of soil gas in other typical fault and earthquake zones in the world. Except for the flux of Rn in the Niudong branch fault 1 and CO₂ in the Niudong branch fault 2, the average values of Rn and CO₂ fluxes in 2021 are higher than those in 2020.The maximum variation of soil gas Rn flux is 116%in the Niudong Fault, and the maximum variation of CO₂ flux is 370%in the Niudong Fault; the variation of soil gas Rn concentration intensity is 119%in the Niudong Fault, but there is no significant variation of concentration intensity in other faults in both periods.
The observation and analysis found that the areas of high soil gas concentration anomalies on the three seismic profiles in XNA are highly coincident with the distribution of deep faults, showing a concentrated degassing phenomenon along the fault zones. The AA' seismic profile on the west side exposes three hidden fractures, which are the Taihangshan Fault, Rongcheng Fault, and one unnamed fault on the west side. The AA' soil gas Rn and CO₂ concentration profiles, corresponding to the location of the upward trend line of the Rongcheng Fault and the unnamed fault on the west side, show the characteristics of simultaneous single-peak type high-value anomalies of Rn and CO₂ concentrations. This phenomenon may indicate that the Rongcheng Fault and the unnamed fault on the west side are still highly active.
The BB' soil gas profile shows two areas of high soil gas concentrations respectively in the east and west. The western high value area shows synchronous peak anomalies of Rn and CO₂ concentrations, and the location of the anomalies is basically consistent with the upward extension direction of the Xushui-Dacheng Fault. In the east, only single-peak anomalies in CO₂ concentration are observed, and the magnitude of the anomalies is more significant than that in the western section, but there is no corresponding fault. Therefore, the synchronous peak anomalies of Rn and CO₂ concentrations in the western section should be related to the fault activity of Xushui-Dacheng Fault, while the single-peak anomalies of CO₂ concentrations in the eastern section may be non-tectonic.
The CC' seismic profile contains the Taihangshan Fault, Niudong Fault, Niudong branch fault 1, Niudong branch fault 2, and several secondary faults. The peak anomalies of soil gas Rn concentration in the soil gas profile are detected at different degrees and near the locations corresponding to the upward extension trend lines of Niudong Fault, Niudong branch fault 1, and Niudong branch fault 2. All three peak anomalies of soil gas Rn concentration may be related to the activities of Niudong Fault, Niudong branch fault 1, and Niudong branch fault 2. However, the single-peak CO₂ concentration anomaly is detected only above the Bazhou Depression, and the anomalous area basically overlaps with the area where the Bazhou Depression is located. The Bazhou Depression is one of the main areas of concentrated population in XNA, and the biological activity is relatively strong. According to the results of the existing study that soil gas CO₂ generated by biological activities may also be the main recharge source of CO₂ gas released from fault zones in the basin, the large-scale CO₂ concentration anomalies detected above the Bazhou Depression may also be generated by biological activities in the basin.
The results show that strong degassing characteristics exist in the main fault zones of XNA. The environmental effects of gas release from the main fault zones in XNA are evaluated by combining with the comprehensive prevention and control standards for indoor gas environmental pollution. The highest value of radon gas release in the main fault zone of XNA reaches 675mBq/m²·s in the Rongcheng Fault, and 395.70mBq/m²·s and 334.84mBq/m²·s in the Nudong branch faults respectively, the results indicate that it is necessary to carry out comprehensive radon prevention treatment for the buildings above the Rongcheng fault and Nudong fault zone. The preliminary estimation results of CO₂ release show that the daily contribution of CO₂ degassing from the main fault zones of XNA to the atmosphere is about 1 622.56t, and the annual contribution is as high as 0.59×10⁶t. Attention should be given to its impact on the regional environment.
The research results in this paper are significant for urban planning, environmental management and comprehensive assessment of the environmental impact of gas release from the fault zone in XNA.

Earthquake is one of the most destructive natural disasters, it can not only cause heavy casualties and economic losses, but also may even lead to serious secondary disasters. As the main bearing body in earthquake, buildings often suffer serious damage, so they can be used as an important reference for post-earthquake disaster loss assessment. Timely and accurate acquisition of regional earthquake damage information after an earthquake is of great significance for scientific and effective emergency rescue and disaster loss assessment. At present, the main methods for earthquake damage identification can be roughly divided into two categories: 1) Manual visual interpretation investigation method. It takes a lot of time for manual field investigation or manual identification of earthquake damage images to process a large amount of seismic damage information in a short period of time, and it is likely to lead to inconsistent discrimination standards for seismic damage of buildings. 2)Image recognition method based on satellite image or UAV image. The recognition method based on satellite remote sensing image after the quake identifies earthquake damage by the texture, brightness and other characteristics of the image of the seriously collapsed buildings, thus, it can quickly get the seismic damage situation in a large area, but as results of offset, low resolution and poor timeliness of the satellite image, it is hard to identify the slightly overlaying and cracking of tiles on the roof of buildings. The combination of high-resolution image obtained by UAV and machine learning algorithm can not only reduce the labor input, but also bring a high accuracy rate. Therefore, based on ant colony algorithm(ACO)and high-resolution remote sensing image of UAV, this paper proposes a new method to efficiently identify the earthquake damage of buildings in the study area, which was applied and verified in the recent Yangbi M6.4 earthquake in Yunnan Province. By improving the update strategy of pheromone concentration in ant colony algorithm and introducing the optimization operator, the better identification rules are established, and the speed and accuracy of earthquake damage identification are enhanced. The UAV high-resolution image of Yangbi county seat was obtained the first time after the Yangbi, Yunnan Province, M6.4 earthquake took place, and taking the image as experimental data, the extraction effect of regional earthquake damage is verified, and compared with ant colony algorithm and maximum likelihood method. The results show that the proposed earthquake damage identification method based on improved ant colony algorithm and UAV high-resolution image can effectively improve the identification accuracy and efficiency of damaged buildings in the region, which is of great significance for post-earthquake emergency rescue and providing accurate disaster information.

On two velocity models, the HypoDD method is used to accurately locate the Tongliao M5.3 earthquake sequence, then the CAP method is used to invert the focal mechanism solutions. The parameters of the seismogenic fault plane are fitted quantitatively by the small earthquake distribution and the regional stress field. The geometry, rupture features and possible seismogenic structure of the Tongliao M5.3 earthquake are comprehensively determined. The HypoDD relocation results show that this earthquake is located at 42.95°N, 122.37°E, the whole sequence trends in NW and major aftershocks (M_L ≥ 3.0) strike in NEE direction. With the time elapsed, the aftershocks extended to the shallow crust gradually. Comparing the focal mechanism solutions and relocation results, we determine that the fitted causative fault based on NNW-trending aftershock distribution is reliable, which has the top left corner (43.00°N, 122.35°E, depth 3.3km), lower left corner (43.00°N, 122.35°E, depth 8.9km), upper right corner (42.92°N, 122.37°E, depth 3.3km), lower right corner (42.92°N, 122.37°E, depth 8.9km), extending range 3km×7km, trending in 349° (NNW), dip angle 86° (nearly vertical), and slip angle 15°. It is inferred that whole process of main shock rupture is from the source to the NW and SE sides as a shear. The rupture degree is larger in southeast where the late rupture concentrated, and did not reach the surface.

Using the 7 100 absolute first arrivals of P waves and 91 513 relative P arrival times of 726 events at the northeastern margin of the Ordos block since 2009, the 3D fine structure of P wave velocity within the depth of 15km in the crust was inverted by the double difference seismic tomography method. The results show that there exist obvious high-speed continuous bodies in the northwest of the study area, and their lateral areas increase gradually with depth, while the velocity of east and south is relatively low. The velocity inhomogeneity exists and differs at different depths. The lateral differences of velocity are related to seismicity and faults. The 5~15km depth profile shows that earthquakes tend to occur in the area with relatively high velocity or high speed transition zones, which to some extent reflects the fragility of regional crustal media and the strong differential movement of faults in vertical and horizontal directions where the crust body is easy to absorb and store strain energy and generate major earthquakes. A "Y"-shape low-velocity channel is present in the lower crust around Liangcheng, corresponding to the NW-trending Heilaoyao-Shahukou fault set, which may reveal the migration path of the Late Tertiary-Quaternary basalt eruption. The Helingeer M6.2 earthquake in 1976 was related to the formation of the locking section of the thermal welding in this area. The three-dimensional fine structure of P wave velocity presented in this paper provides intuitive seismological evidence for physical and chemical properties of crustal media and the deep tectonic environment of earthquake preparation.

Three-dimensional scanning with LiDAR has been widely used in geological surveys. The LiDAR with high accuracy is promoting geoscience quantification. And it will be much more convenient, efficient and useful when combining it with the Unmanned Aerial Vehicle (UAV). This study focuses on UAV-based Laser Scanning (UAVLS)geological field mapping, taking two examples to present advantages of the UAVLS in contrast with other mapping methods. For its usage in active fault mapping, we scanned the Nanpo village site on the Zhangxian segment of the West Qinling north-edge fault. It effectively removed the effects of buildings and vegetation, and uncovered the fault trace. We measured vertical offset of 1.3m on the terrace T₁ at the Zhang river. Moreover, we also scanned landslide features at the geological hazard observatory of Lanzhou University in the loess area. The scanning data can help understand how micro-topography affects activation of loess landslides. The UAVLS is time saving in the field, only spending about half an hour to scan each site. The amount of average points per meter is about 600, which can offer topography data with resolution of centimeter. The results of this study show that the UAVLS is expected to become a common, efficient and economic mapping tool.