Distribution Of Faults Research Articles

Seismogenic Faults of the Changning Earthquake Sequence Constrained by High-Resolution Seismic Profiles in the Southwestern Sichuan Basin, China

Abstract The seismicity rate in the southwestern Sichuan basin, China, dramatically increased after 2014. The associated moderate earthquakes may have been induced by salt mining or shale gas exploration. The location of the seismogenic faults causing these moderate earthquakes has not been confirmed, resulting in a lack of understanding of the earthquake mechanisms in the study area. The detailed structural characteristics of pre-existing faults, which are typically responsible for induced seismicity, are unclear. In this study, we used high-resolution seismic reflection profiles in conjunction with geological, seismologic, and geodetic data to reveal the 3D distributions of the seismogenic faults. Basement thrust faults in the Changning anticline were identified using seismic interpretations and are associated with the 2019 Changning earthquake sequence. The geometry and location of these pre-existing faults are consistent with previous studies of the seismology and structural geology in the area. The well-developed pre-existing fault system in the sedimentary cover and basement makes the Changning area vulnerable to induced earthquakes. Present-day reactivation of the basement fault system reveals the unstable state of the local tectonic stress field. It is possible that the potential seismic risk in this region could be increased by industrial activity in the southwestern Sichuan basin.

Developing a hybrid software reliability growth model

PurposeThe purpose of this paper is to develop a new software reliability growth model considering different fault distribution function before and after the change point.Design/methodology/approachIn this paper, the authors have developed a framework to incorporate change-point in developing a hybrid software reliability growth model by considering different distribution functions before and after the change point.FindingsNumerical illustration suggests that the proposed model gives better results in comparison to the existing models.Originality/valueThe existing literature on change point-based software reliability growth model assumes that the fault correction trend before and after the change is governed by the same distribution. This seems impractical as after the change in the testing environment, the trend of fault detection or correction may not follow the same trend; hence, the assumption of same distribution function may fail to predict the potential number of faults. The modelling framework assumes different distributions before and after change point in developing a software reliability growth model.

Assessment of Health Monitoring Trustworthiness of Avionics Systems

The article provides a methodology for assessing the trustworthiness of health monitoring the dismounted avionics systems with automated test equipment (ATE). The indicators include the probabilities of false-positive, false-negative, true-positive, and true-negative. For the first time, we introduced into consideration the instability of the source of stimulus signal (SSS), the random and systematic component of the measuring channel error, and the reliability characteristics of the systems themselves. We consider a specific case of an exponential distribution of permanent failures and intermittent faults and derive formulas for calculating the trustworthiness indicators. Numerical calculations illustrate how the probabilities of correct and incorrect decisions depend on accuracy parameters. We show that the probabilities of false-positive and false-negative increase much faster than the probabilities of true-positive and true-negative decrease when the standard deviation of stimulus signal increases. For a Very High-Frequency Omni-Directional Range (VOR) receiver, we demonstrate that even with a zero random error generated by the source of the stimulus signal, the probabilities of false-positive and false-negative are different from zero.

GROUNDWATER MODELING IN SANGON HAMLET AND SURROUNDING AREAS USING FINITE DIFFERENCE METHOD

Sangon Hamlet is included in the mountains which are dominated by andesite rocks and volcanic breccias which cross each other and have a distribution of joints and faults forming a fracture. The fracture is a medium for draining water in the area. There is a difference in ground water level as seen from the well. To re-detail the groundwater flow that has been formed, a groundwater flow pattern modeling is carried out. The modeling is done by numerical method assisted by Modflow Flex Software. For building the model, it is necessary to prepare a concept model, calibration and validation. In this area there are 2 aquifer systems, namely unconfined aquifers and aquitards. Furthermore, the model was calibrated using the sensitivity analysis method. The calibration results are obtained, namely the RMS value of 8.74% with a standard error estimate of 1.27 m and a correlation coefficient of 0.98. From this model, it is known that the flow of water moves from the northwest-north area in the form of a plateau by heading to the east-southeast area which is a lower plain and towards the Plampang River.

Preventive maintenance period decision for elevator parts based on multi-objective optimization method

Elevator maintenance plays an important role in the safe and reliable operation of elevators. However, elevator maintenance is carried under some relevant norms and standards at present, and little research has been conducted to explore how to analytically make maintenance period decision for elevator parts. In addition, the unreasonable selection of the elevator maintenance period will cause excessive cost and low equipment operation efficiency. A decision-making method for elevator parts' maintenance is provided in this paper, which aims to solve the problem of seeking a reasonable maintenance cycle for elevator parts. First of all, the historical fault data of elevator parts is used to analyze their fault distribution law. In order to accurately reflect the changes of parts after maintenance and repair, the age reduction factor and the failure rate increasing factor are introduced to establish a mixed failure rate model. Accordingly, the cost rate and utilization rate model are established under the comprehensive consideration of cost and time factors in the maintenance process. Furthermore, a multi-objective optimization model is built with maintenance frequency as the decision variable. Then, Monte Carlo simulation method is used to solve the optimization model, and the best maintenance period of the parts within the service time is obtained. Finally, the proposed method is applied to the elevator parts to find out their optimum maintenance frequency, and the results show the effectiveness of the method. A reasonable maintenance period can not only reduce the risk of equipment failure, but also save costs so as to avoid excessive waste of resources.

Submarine Active Faults and Morpho-Tectonics Around the Iberian Margins: Seismic and Tsunamis Hazards

The aim of this work is to make a synthesis at regional scale focused on the geophysical characterization of submarine faults around the Iberian margin to identify active structures and analyze their development in the framework of the present plate organization. Most of these submarine faults show seabed morphological expressions mapped with high-resolution swath bathymetry data, high-resolution parametric sub-bottom profiles and multichannel seismic profiles. Present active tectonics, deformation, seismicity, and tsunami-affected coastal areas is mainly focused on south Iberia at the Eurasian and Nubia plate boundary. Submarine active faults in these areas are represented by long strike-slip fault systems and arcuate fold-thrust systems. Their development takes place in response to present NW-SE convergence between the Eurasian and Nubia plates. We propose a strain partitioning model of the plate boundary into simple and pure shear zones to explain the distribution and mechanisms of active submarine faults along the Gulf of Cádiz, Gibraltar Arc and Alborán Sea in response to the present-day shear stress orientation. Nevertheless, deformation is also focused in the NW Iberian margin. Thus, along the Galician and Portuguese margin, several submarine faults mapped as thrust fault systems with high-seismic activity along the Iberian ocean-continent transition reflect the re-activation of former structures. We suggest that submarine active faults in the NW and W Iberia are also the response to the eastwards transfer of short-offset transform faults of the Mid Atlantic Ridge into the oceanic Iberian along a weakness as the former plate boundary between the oceanic Iberia and Eurasia domains. The distribution and activity of submarine faults mapped in this work from geophysical and bathymetric data are in good agreement with geodetic data and focal mechanisms.

The 2019 Ms 4.2 and 5.2 Beiliu Earthquake Sequence in South China: Complex Conjugate Strike-Slip Faulting Revealed by Rupture Directivity Analysis

Abstract The South China block has been one of the most seismically quiescent regions in China, and the geometries and activities of the Quaternary faults have remained less studied due to the limited outcrops. Thus, source parameters of small-to-moderate earthquakes are important to help reveal the location, geometry distribution, and mechanical properties of the subsurface faults and thus improve the seismic risk assessment. On 12 October 2019, two earthquakes (the Ms 4.2 foreshock and the Ms 5.2 mainshock) occurred within 2 s and are located in southern South China block, near the junction region of the large-scale northeast-trending fault zones and the less continuous northwest-trending fault zones. We determined the point-source parameters of the two events via P-wave polarity analysis and regional waveform modeling, and the resolved focal mechanisms are significantly different with the minimum 3D rotation angle of 52°. We then resolved the rupture directivity of the two events by analyzing the azimuth variation of the source time duration and found the Ms 4.2 foreshock ruptured toward north-northwest for ∼1.0 km, and the Ms 5.2 mainshock ruptured toward east-southeast (ESE) for ∼1.5 km, implying conjugate strike-slip faulting. The conjugate causative faults have not been mapped on the regional geological map, and we infer that the two faults may be associated with the northwest-trending Bama-Bobai fault zone (the Shiwo section). These active faults are optimally oriented in the present-day stress field (northwest-southeast) and thus may now be potentially accumulating elastic strain to be released in a future large earthquake.

Seismic attributes for characterization and prediction of carbonate faulted karst reservoirs in the Tarim Basin, China

An ultradeep, faulted karst reservoir of Ordovician carbonate was discovered in the Shunbei area of the Tarim Basin. Fractured-cavity reservoirs buried beneath the large thickness of upper Ordovician mudstone were formed along the fault-karst belts. The hydrocarbon accumulation in these reservoirs is controlled by the fault system, and the oil-gas accumulation was affected by karstification and hydrothermal reformation. Previous studies and 2D modeling revealed that the reservoirs had “bright spot” amplitude responses like “string beads,” and they have developed along the strike-slip faults. However, describing such a complex fault-controlled karst system is still a difficult problem that has not been well addressed. We have sought to instruct the attribute expression of faulted karst reservoirs in the northern part of the Tarim Basin. We applied coherence and fault likelihood (FL) seismic attributes to image faults and fractures zones. We then used a trend analysis method to calculate the residual impedance from the impedance of the acoustic inversion, using the fact that residual impedance has higher lateral resolution in reservoir predictions. Finally, we integrated the coherence, FL, and residual impedance attributes into a new seismic attribute, the “fault-vuggy body,” with a certain fusion coefficient. The fault-vuggy body attribute establishes a connection between faults and karst cavities. This method could help in the characterization and prediction of carbonate faulted karst reservoirs. Available drilling data were used to validate that the fused fault-vuggy body attribute was an effective reservoir prediction method. As the seismic sections and slices along the layer help delineate, the distribution of bright spots and strike-slip faults indicates that the main strike-slip fault zones are the most favorable reservoirs in the Shunbei Oil and Gas Field.

Gravity data as a faulting assessment tool for unconventional reservoirs regional exploration: The Sergipe–Alagoas Basin example

This paper introduces a gravity regional interpretation workflow for mapping the natural fracture system, a challenge in unconventional reservoir exploration. The workflow comprises coupling two gravity data attributes, the tilt angle and the multiscale edge detection (worming), to build a high-resolution image structural framework of a given basin’s basement. That includes a description of the fault directions and fault density, consolidated in a fault distribution map. The proposed workflow was applied to available gravity data of a representative passive-margin basin, the Sergipe-Alagoas Basin, Brazil. The source rocks of Sergipe-Alagoas are organic-rich shale deposited in the principal depocenters during the rift phase of the basin’s evolution. These shaly units are the unconventional reservoirs in the basin. These organic-rich shales are acknowledged as syn-rift unconventional reservoir analogs of all Brazilian continental margin basins and many other passive-margin basins worldwide. The workflow recognized two fault trends in the studied area. A principal NE–SW and a minor NW–SE. 3D seismic interpretation validated the proposed workflow by successfully associating the gravity faults with traditional fault attributes. One advantage of this workflow is that it can be implemented over broad regions at a minimum expense. The proposed method can be used to rank opportunities in unconventional exploration.

Learning from unlabelled real seismic data: Fault detection based on transfer learning

ABSTRACTSignificant advances have been made towards fault detection using deep learning. However, the fault labelling of seismic data requires great human effort. The resulting small sample problem makes traditional deep learning methods difficult to achieve desired results. Existing research proposes to train a deep learning model with labelled synthetic seismic data to get good fault detection results. However, due to the complexity of the actual geological situation, there are inevitable differences between synthetic seismic data and real seismic data in many aspects such as seismic signal frequency, frequency of fault distribution and degree of noise disturbance, which lead to the fact that the deep learning model trained by synthetic seismic data is difficult to get good fault detection result in field data applications. We propose to use transfer learning to reduce the impact of data differences to solve this problem: part of the deep transfer learning model is used to learn fault‐related features. And the other part of the deep transfer learning model is used to mine common features between the real seismic data and the synthetic seismic data, which makes the deep transfer learning model more suitable for real seismic data. Compared with the latest research progress, our method can greatly improve the effect of fault detection without real data label, which can significantly save the cost of manual label processing.

Characterization of the accommodation zones along restraining and releasing bends from analogue modelling simulating the seagap fault, off-shore Tanzania

The study aims to understand geometry and evolution of accommodation zones along restraining and releasing bends in strike slip systems which is often complex and characterized by sharp change in polarity, resulting in a difficult characterization of traps location. A batch of sandbox modelling experiments was performed using a layered scaled sand material. The setup parameters of the wooden baseplates used in the first two experiments (SS1 and SS2) are basement offset of 6.5 cm/3 cm, 90°/90° stepovers in releasing and restraining bends of total 96 cm length and 25 cm width. The third experiment (SS3) was performed with basement offset of 6.5 cm/3 cm, 156°/126° stepovers in releasing and restraining bends of total 96 cm length and 25 cm width. The experiments were performed with special attention to the role of syn-kinematic sedimentation and the pre-existing structure of the basement. A sequence of pop-up and pull-apart structures was produced. Along the main structures, complex fault trend was compatible with a sinistral riedel distribution and a counterclockwise rotation of pre-existent elements. Change of fault's polarity at depth and dip direction flipping of high angle faults in accommodation zones were clearly observed. Even more, progressive propagation of the pop-up structures produces a spectacular inversion of adjacent extensional structures. Comparing results of the model with the Seagap fault zone, it is possible to put in evidence similar fault orientation and distribution. Internal structures developed were strongly influenced by syn-kinematic sedimentation as observed by characteristic helicoidal shape of growth faults. The analogue models clearly describe how boundary faults of the pull-apart basin along a paired bend, initially characterized by a normal kinematic can be subsequently inverted in the later stages, which can potentially have a strong impact on the petroleum system.

Characterization and Distribution of Cenozoic Polygonal Fault: Case Studies in West Africa and Vietnam Continental Margins

The Cenozoic sequence of offshore Cameroon and Vietnam has been analysed based on newly 1500 km2 3D seismic data (Kribi-Campo basin) and 75 km 2D seismic data (Hoang Sa basin). Polygonal faults are widely developed in both passive margins and have relatively similar characteristics. These highly faulted intervals are up to c. 1000 m, characterized by normal faults with a throw of 10-20 ms TWT and 100 m - 1000 m spacing, displaying a polygonal pattern in the map view. Polygonal faults in the Kribi-Campo basin developed almost in the entire Cenozoic sequence mainly in two sets, one in deep section and one in shallow section whereas the Hoang Sa basin developed the polygonal fault only in the shallow section up to the seafloor corresponding to the Pliocene- Pleistocene sequence. In the Kribi-Campo basin, polygonal faults are developed extensively in the high gradient slope (3.4o) which is relatively rare in the low gradient slope (0.7o). Hoang Sa basin shows the widespread polygonal fault except for the area of canyon occurrence. The occurrence of thick and widespread polygonal fault formations associated with the low amplitude reflections suggests the interpretation of fine-grained sediments, thus possibly great seal potential for the study areas.

High resolution morphometric analysis of the Cordone del Vettore normal fault scarp (2016 central Italy seismic sequence): Insights into age, earthquake recurrence and throw rates

We investigated the late Quaternary throw distribution of the main normal fault that ruptured during the Mw 6.5 2016 earthquake in central Italy by means of a high-resolution structure-from-motion (SfM)-derived Digital Surface Model (DSM). We focused on a key area along the Cordone del Vettore fault (CDV), which is part of the Vettore-Bove fault system (VBFS). The CDV displays a prominent compound post-glacial scarp that allowed the reconstruction of the along-strike cumulative throw distribution. We propose a geometric approach to calculate the CDV fault throw distribution from the reconstruction of a displaced glaciation-related erosional surface, used as a geomorphic marker, and a series of closely spaced cross profiles. The proposed calculation accounts for both the slip vector direction and the degraded scarp top, including field data on fault dip angles. Following this approach, we recognized two scarps with a minimum average fault throw of ~21 m and ~35 m for this section of the investigated fault strand.The correlation with the possible post-LGM (Last Glacial Maximum) deglaciation phases of the erosional surface suggests a minimum scarp age of 25–27 ka cal BP. Such an age provides a reasonable CDV fault throw rate of ~0.8 mm/a, comparable with known long-term throw rates of the VBFS and active Apennines normal faults. By comparing the reconstructed long-term Cordone del Vettore throw distribution with the 2016 coseismic one, ~24 2016-like surface faulting events are required to generate the main cumulative scarp, under the assumption of constant slip per event. This, along with the age of the scarp, yields an average earthquake recurrence time interval of ~1100 a. These results suggest the presence of multiple regional markers that correlates with different LGM (if not pre-LGM) major glacial phases, whose erosional processes allow the preservation of pre-existing bedrock fault scarp remnants.

Present-day movement trends of the major tectonic faults in the Sichuan-Yunnan region based on the constraint of GPS velocity fields

Based on the known fault distribution in Sichuan-Yunnan region (SYR), a rigid Euler rotation model is constructed by using GPS velocities (1998 ~ 2016) after excluding the stations near the fault boundaries and simultaneously a translation-rotation-strain model is constructed by using almost all GPS velocities to calculate three periods strain rate fields (2008.6 ~ 2010.4, 2010.5 ~ 2013.4 and 2013.5 ~ 2016.12) after Wenchuan earthquake. The results show that: (1) the strike-slip activity is the most common trends for the regional faults. The Xianshuihe-Xiaojiang fault, the Lancangjiang-Weixi-Weishan-Wuliangshan fault and the Longmenshan fault are the most active in the whole SYR, and the dislocation rate is more than 15 mm/a, and the trend of activity gradually decreases from the northwest to the southeast. (2) The different activity rates of the faults in the study area indicate that some of the eastward extrusion of the Tibet Plateau is absorbed and adjusted by the inside faults, and it is not a few large strike-slip faults. (3) Through the analysis of three periods’ grid velocity fields, we found that the movement rates of the Bitu section of Lanchangjiang fault, the Northwestern section of Weixi-Weishan fault and the Nujiang fault after Wenchuan earthquake are larger than that after Yushu and Ya’an earthquake, and the difference is about 8 mm/a. Besides, the activity rate of Northwestern section of Longmenshan fault after the Wenchuan earthquake is larger than that after the Ya’an earthquake, although the two epicentres distances are relatively close. (4) The strain rate fields and surface expansion rates show that the high value area is mainly distributed at or around the intersection among some fault zones and its surroundings, and the maximum area is mainly located at some long and deep fault zones such as the Longriba fault, the Longmenshan fault zone, the Ganzi-Yushu fault and the Xianshuihe, and the magnitude is about 35 ~ 50 nanstrain/a. The research should provide fundamental material for the study of crustal stress variation and earthquake prediction in Sichuan-Yunnan region.

Influence of crustal rheology and heterogeneity on tectonic stress accumulation characteristics of North China constrained by GNSS observations

Abstract North China is characterized by significant lithosphere heterogeneity and numerous faults, with the occurrence of many historical and ongoing devastating earthquakes. To extend our understanding of the mechanisms of seismicity initiation and fault activity due to lithospheric rheology and lateral difference, we first established a three-dimensional viscoelastic finite element model based on the lithospheric lateral heterogeneity of physical properties across the north–south gravitational lineament (NSGL), spatial distribution of faults, and interseismic global navigation satellite system (GNSS) velocities (1999–2018). We then analyzed the stress accumulation characteristics across the NSGL and its relationship with seismicity. Finally, we explored the temporal and spatial variations of stress along major faults and further analyzed potential relationships between the stress components and rupture mechanisms of typical faults. The results showed that high maximum shear stress, mainly distributed in eastern North China (ENC) and western North China (WNC), corresponding to the focal depth, which suggests that the different brittle crustal thicknesses across the NSGL may be one of the major factors that dominates earthquake depth in North China. Significant maximum shear stress is mainly accommodated on faults around the Ordos Block in WNC and northern faults in ENC, which is consistent with frequent seismic activity in these regions. The relationship between the calculated stress components and rupture mechanisms of typical faults imply that the differential tectonic loading from neighboring blocks may be one of the major dynamic factors for seismogenic processes in North China.

Geology Assessment of Permeability Distribution in Silangkitang Geothermal Field, North Sumatra, Indonesia

The Silangkitang (SIL) geothermal system is a fault-controlled and liquid-dominated reservoir associated to a deep heat source. Geology data from recent development drilling and reservoir monitoring demonstrated that the high permeability is concentrated within zone between two strands of Great Sumatra Fault (GSF). These faults are major dextral strike slip system that cross the entire length of Sumatra Island. The fault distribution has been defined by integration and interpretation of tectonic geomorphology, surface geology, and well geology. The highest permeability is controlled by faults and fractures associated with localized releasing steps within west of main Tor Sibohi Fault (TSF). This paper outlines the indication of high permeability zone based on recent geology evaluation outcome.

Integrated Exploration Model for Concealed Ore Deposit: A Case Study from Shuitou Fluorite Deposit, Inner Mongolia, North China

The demand for fluorite resource is increasing rapidly as most fluorite deposits on Earth’s surface have been exhausted. The newly discovered fluorite deposits in Inner Mongolia are hosted by Permian metamorphosed sandy slate, intermediate-acid intrusive rocks and Cretaceous volcanic sedimentary rocks. The ore bodies are strictly controlled by faults and buried by cover rocks. The feasibility and effectiveness of multi-techniques for prospecting concealed fluorite ore bodies are evaluated, and 10 anomalies are delineated. On the basis of geological features and effectiveness of different methods, the optimum combinations of ore prospecting techniques are proposed for the exploration of zonal type and burial type concealed fluorite ore bodies. Based on comprehensive researches, an integrated exploration model is proposed: (i) select key prospecting targets based on geological backgrounds, regional geochemical anomalies of F and Ca, and remote sensing images; (ii) identify the spatial distribution of low resistivity anomaly and ore-controlling structure from geophysical survey; (iii) evaluate the mineralization potential in fault zone based on F and Ca anomalies in key sections selected from low resistivity anomaly zones; and (iv) evaluate the mineralization potential and reveal the spatial distribution of fluorite ore bodies and ore-controlling faults based on integrated geophysical and geochemical anomalies. The integrated exploration model is verified to be a powerful tool for prospecting concealed fluorite ore bodies in coverage area.

A transfer fault complex to explain the geodynamics and faulting mechanisms of the 1976 M7.8 Tangshan earthquake China

Abstract The geodynamics and faulting mechanism of the M7.8 Tangshan earthquake (China, 28th July 1976) are re-examined within a framework of a transfer fault complex that has strike slip, thrust and normal faulting components. The locations of the faults are conditioned by the locations of the 30 largest shocks (M > 5) of the sequence from 28th July 1976 to 27th November 1977. We find that the shocks are naturally arranged into three discrete time–space constrained sequences, and two linked transfer fault complexes are required to explain the data. We validate the transfer fault model by comparing the distribution of faults as we map them with the distribution of 247 M > 4 aftershocks that occurred from 1 September 1976 to 31 December 1979, the distribution of recent H2 and He soil gas anomalies from 756 sites spread across the extensive fault zone and the distribution of large animal behaviour and telluric current anomalies. We find a high degree of conformity between the transfer faults as we map them and these other data sets, with some degree of inconsistency that we use to refine the transfer fault model. Our main conclusion is that event 1 (M7.8) of the Tangshan earthquake occurred on the dextral strike slip leg of a transfer fault on the edge of the Bohai Bay Basin and as such is an integral part of the on-going evolution of that basin where a new active rifting phase may have begun during the Quaternary.

Fault identification approach and its application for predicting coal and gas outbursts

The formation and development of faults are a manifestation of stress concentrations and energy release in crustal rocks, and faults have a great influence on the occurrence of dynamic mine disasters. This study proposed mapping technology as a fault identification method. The mapping procedure included four steps: (1) Drawing points on topographic maps. The information of topographic maps, such as elevation, rivers, and lakes was copied onto sulfuric acid paper. (2) Classifying the landform. Based on the highest and lowest points in the studied area, the minimum elevation difference was calculated and the elevation points were graded according to the minimum elevation difference. (3) Determining the block boundaries. The elevation points in the same grade were categorized into the same blocks. (4) Mapping the fault distribution. The boundaries between different blocks were considered as faults. In this regard, numbers were assigned to the faults, and a graphic scale, coordinate grid, and legends were added to the map. Fault identification for classes I–V was conducted at different scales. Fault identification for the next class always retained the previous results. Using this method, the faults in the Pingdingshan coal mining zone were divided into classes I–V. By comparing the classes with historical coal and gas outbursts, it was indicated that more than 90% of the coal and gas outbursts occurred in the vicinity of faults, especially at the intersections of multiple faults and in areas with concentrated faults. This study provided a scientific basis for predicting coal and gas outbursts.

Amplitude variation characteristics of active source airgun signals at Qilian Mountain

In this study, Qilian Mountain active source airgun signals recorded at 79 stations were obtained after stacking waveforms from July 2015 to December 2016. Based on analysis of the amplitude variation characteristics of the airgun signals, the following conclusions were drawn: along the NW-SE fault distribution direction of the Qilian Mountain area, the decrease in amplitude of airgun signals was relatively slow in relation to the epicentral distance, while the decrease in amplitude in the direction perpendicular to the fault was relatively fast. This difference may be related to the energy loss of seismic waves reflecting and scattering by the regional faults mainly distributed along the NW-SE direction, which are caused by tectonic compression of the Qinghai-Tibet and Alxa blocks.