Haijiang Zhang

University of Science and Technology of China | USTC · Department of Geophysics and Planetary Sciences

We incorporate body-wave arrival time and surface-wave dispersion data into a joint inversion for three-dimensional P-wave and S-wave velocity structure of the crust surrounding the site of the San Andreas Fault Observatory at Depth. The contributions of the two data types to the inversion are controlled by the relative weighting of the respective...

The Zhangjiakou-Bohai Seismic Belt (ZBSB) is a crucial intraplate seismic belt in Eastern China, covering densely populated and economically developed regions with significant seismic hazards. A refined model is essential to investigate the intraplate seismic mechanism here. We obtained the three-dimensional resistivity model based on magnetotellur...

To better understand factors controlling the distribution of volcanoes, plate coupling along the subducting plate interface, and the transition from normal to flat slab subduction, we have determined high-resolution Vp, Vs and Vp/Vs models in the central Chile subduction zone where normal slab subduction transits to flat slab subduction. In the stu...

Seismic tomography is a methodology to image subsurface properties of the Earth. In order to better interpret the resulting images, it is important to assess uncertainty in the results. Mixture density networks (MDNs) provide an efficient way to estimate Bayesian posterior probability density functions (pdfs) that describe the uncertainty of tomogr...

V P and VS models have been obtained for the lithosphere of Chinese continent by tomography of body-wave travel times, surface-wave data, and joint inversion of surface- and body-wave data. However, the VP/VS ratio model derived directly from them shows unphysical values, indicating internal inconsistency of model resolutions and uncertainties. In...

Plain Language Summary According to observations and analysis, the velocities of plates entering the trench are much higher than the slab sinking rate in the lower mantle. Inconsistent velocities at the slab's two ends must be accommodated by slab deformation or accumulation in the middle mantle to ensure mass conservation. We have considered three...

Seismic tomography is a crucial technique used to image subsurface structures at various scales, accomplished by solving a nonlinear and nonunique inverse problem. It is therefore important to quantify velocity model uncertainties for accurate earthquake locations and geological interpretations. Monte Carlo sampling techniques are usually used for...

Plain Language Summary Wave equations based seismic imaging method theoretically possesses the most effective capacity for characterizing crustal and upper mantle strong laterally heterogeneous structures. However, its advantages have not been well manifested in the imaging of lithospheric structures, primarily due to the uncertainties introduced b...

In the Changning region of the Sichuan Basin, China, which has experienced decades-long injection of freshwater for commercial salt mining, a Ms 6.0 earthquake occurred in June 2019, along with four Ms >5 aftershocks. Using data from local and regional seismic stations, we determine accurate locations for this earthquake sequence, velocity structur...

Formation of the Tibetan Plateau is generally ascribed to the Cenozoic India–Asia collision. However, the origin of along-strike deformation of the Indian mantle lithosphere, especially beneath the eastern Tibetan Plateau region, and its effect on the plateau’s eastward growth remain unclear. Here, we conduct multiscale seismic tomography to provid...

Rock pillars in rock engineering are affected by the stress concentration, which is uneven and can lead to potential instability after loading disturbance. In this paper, considering the heterogeneity of the rock, time-dependent velocity tomography based on the Kalman filter system is adopted to invert the velocity evolution of the rock monitored v...

Due to the uneven spatial and temporal distribution of noise sources, the dispersion data extracted from high-frequency (>1Hz) ambient noise data would be contaminated and biased. Based on the azimuth analysis of the noise sources, we propose a linear array data acquisition strategy that considers the noise source direction to get high quality disp...

The lithospheric structure of continental China has been previously determined by seismic travel time tomography, surface wave tomography, and joint inversion of body wave and surface wave data. However, due to the inherent limitations of seismic data, the lithospheric structure of continental China is still not well resolved in the shallow part an...

The Sichuan-Yunnan area is located at the southeastern margin of the Tibetan Plateau, where tectonic movement is strong with deep and large faults distributed in a staggered manner, which results in strong seismic activities and severe earthquake hazards. Since the 21st century, several earthquakes of magnitude 7.0 or above occurred in this region,...

Rare earth element ore deposits associated with carbonatite derived from Earth’s mantle supply half of the world’s rare earth element. However, the formation of carbonatite and initial enrichment and transport of rare earth element in the mantle, is unclear. Here, we image the lithospheric architecture of a Cenozoic rare earth element ore belt in s...

On 3 August 2014, a destructive earthquake with a magnitude of 6.5 occurred in the Ludian region in Yunan, China, causing heavy casualties. However, the seismogenic structure of the Ludian earthquake is still unclear. To address this issue, we have developed a three‐dimensional joint inversion algorithm for magnetotelluric data and seismic body wav...

In geotechnical engineering projects, rock masses are subjected to various degrees of disturbance from geotectonic movements, rock drilling and mining before they are subjected to dynamic loads such as rock bursts, earthquakes, and blasting. We aim to investigate the dynamic mechanical properties, strain field, energy evolution, and progressive cra...

The Jinsha River flows through the tectonically active Sichuan and Yunnan regions, which have frequent strong earthquake activities. Four large-scale hydropower dams have been built in the lower reaches of the river and had begun impounding water successively since October 2012, with the Baihetan (BHT) and Xiluodu (XLD) being the second and fourth...

Moderate to strong earthquakes have been induced worldwide by shale gas development, however, it is still unclear what factors control their behaviors. Here we use local seismic networks to reliably determine the source attributes of dozens of M > 3 earthquakes and obtain a high-resolution shear-wave velocity model using ambient noise tomography. T...

The current lithospheric root of the South China Block has been partly removed, yet what mechanisms modified the lithospheric structure remain highly controversial. Here we use a new joint seismic inversion algorithm to image tabular high-velocity anomalies at depths of ~90–150 km in the asthenosphere beneath the convergent belt between the Yangtze...

On 21 May 2021, the MS 6.4 earthquake struck Yangbi County, Dali City, Yunnan Province. Minor seismic activities were common both before and after the earthquake; the foreshock sequence activity characteristics of this earthquake were studied to gain a better understanding and more perspective. First, between May 18 and 5 July 2021, we collected da...

In this study, high-resolution Moho depth and average crustal Vp/Vs ratio distributions in northeast China were obtained through joint inversion of receiver functions and gravity data. The new joint inversion method comprehensively considers the complementary imaging strengths of the receiver functions in the vertical direction and the gravity data...

Hydraulic fracturing has been widely used in coalbed methane (CBM) extraction to improve its efficiency. The evaluation of the spatial distribution of fractures produced by hydraulic fracturing is crucial for improving resource utilization and reducing potential gas outburst risks. In the process of hydraulic fracturing, the generation of cracks wi...

Water inrush from the floor of the coal mining face is one of the main disasters in the process of deep coal mining in China, and its occurrence is related to the geological conditions of the coal seam and the mining activities. In the process of coal mining, the floor can be perturbed and damaged, and the original fracture zone for fluid uplifting...

水力压裂技术已经广泛应用于煤层气抽采以提高抽采效率.水力压裂产生裂缝的空间分布评价对于提高资源的利用率和降低潜在的瓦斯突出风险至关重要.在水力压裂过程中,裂缝的产生会伴随微地震的产生,因此微地震监测可以用于水力压裂效果的评价.目前煤层气水力压裂微地震监测主要是依赖微地震定位得到的空间分布,不能准确和全面评价储层的改造效果.为此,提出综合利用微地震定位和速度成像综合评价煤层气水力压裂改造效果.针对中国山西的两口煤层气水力压裂井地面微地震监测数据,利用双差地震成像算法确定了更精确的地震定位和目标煤层附近的速度异常分布.定位结果显示微地震主要分布在压裂井附近并且呈簇状分布,和传统定位相比双差成像给出了更精确的微地震空间分布.根据微地震的空间分布,估算了储层的压裂改造区域.双差地震速度成像显示微地震...

Seismic activity near the shale gas fields in the Sichuan Basin of China has risensignificantly in the past few years. Due to the lack of industrial stimulation data to the public, it is difficult to directly link the surge in seismicity near the shale gas fields with hydraulic fracturing stimulation. Meanwhile, it is also challenging to better und...

Current extensive seismicity in southern Sichuan Basin is ascribed to the reactivation of pre-existing faults, as a result of prolonged fluid injection for salt mining and shale gas development, respectively. However, the structural framework of the region remains poorly understood. Here, we apply Vp/Vs consistency-constrained double-difference sei...

地壳厚度和波速比是研究地壳结构和组分的两个重要参数，可为区域构造研究提供重要约束。接收函数被广泛地用于确定地壳厚度和波速比，例如H-κ方法或H-κ-c方法，但是该方法只能确定台站下方的地壳厚度和速度比，当地震台站分布稀疏时，很难约束台站间的横向不均匀性。另一方面，重力数据也可用于莫霍面的起伏变化研究，它在横向上覆盖很好，有较高的分辨率，但在纵向上分辨率相对较低。为此，本研究提出了一种联合反演算法求解莫霍面深度和地壳波速比参数。联合反演算法综合考虑了接收函数在纵向上的较高分辨率和重力数据在横向上的较高分辨率，同时拟合区域内所有台站上的接收函数和区域重力数据。模型测试表明联合反演算法较单一的接收函数反演更精确，特别是对于地壳厚度的确定。

Low-frequency signals have been widely found in the conventional oil/gas field and volcanic region as well as during hydraulic fracturing of unconventional oil/gas reservoirs. Their generation mechanism has been ascribed to the flow of gas/fluid in the fractures, which can induce the Krauklis wave around fractures and can further excite low-frequen...

This study, via combined analysis of geophysical and geochemical data, reveals a lithospheric architecture characterized by crust-mantle decoupling and vertical heat-flow conduits that control orogenic gold mineralization in the Ailaoshan gold belt on the southeastern margin of Tibet. The mantle seismic tomography indicates that the crust-mantle de...

Crustal thickness and Vp/Vs ratio are two important parameters for understanding crustal structure and composition, which can help to study regional tectonics. Receiver function analysis has been widely used for determining crustal thickness and Vp/Vs ratio by the method or the method. However, it can only acquire average crustal thickness and Vp/V...

Earthquakes are supershear when their rupture speed is faster than that of the seismic shear waves produced. These events are rare, but they can be highly destructive owing to the associated strong ground shaking, and understanding why they occur may provide insights into fault mechanics. Only a few supershear earthquakes have been reported previou...

Chao Lake is a Geoheritage site on the active Tan-Lu Fault between the Yangtze craton, the North China craton, and the Dabie orogenic belt in the southeast. This segment of the fault is not well constrained at depth partly due to the overprinting of the fault zone by intrusive materials and its relatively low seismic activity and sparse seismic sta...

We have developed a new joint inversion method that incorporates body wave arrival times, surface wave dispersion and receiver functions to simultaneously update earthquake locations and constrain three‐dimensional P‐wave (Vp) and S‐wave velocity (Vs) models. Due to complementary sensitivities of the three types of data, the proposed joint inversio...

To monitor the status of cavern roof instability induced by solution salt mining, we deployed a surface microseismic monitoring system for Dongxing salt mine, Dingyuan county, China. The microseismic monitoring system consists of 11 three-component geophones installed in shallow holes of 5 m deep. From 7-month continuous monitoring data, we have de...

Recently, a Mw 7.1 earthquake struck the Pacific coast of northeastern Japan on 2021/02/13. To investigate the cause of this earthquake and its aftershocks, we applied a Vp/Vs model-consistency constrained double-difference (DD) seismic tomography method to the earthquake arrival time data from the dense seismic networks in Japan to image the veloc...

By taking advantage of the information carried by the entire seismic wavefield, Full Waveform Inversion (FWI) is able to yield higher resolution subsurface velocity models than seismic traveltime tomography. However, FWI heavily relies on the knowledge of source information and good initial models, and could be easily trapped into local minima caus...

Seismic imaging using ambient noise has been widely used to image subsurface structures. The spatial autocorrelation (SPAC) method using ambient noise recorded by seismic arrays can image subsurface velocity structures at various scales. In addition, an approximation of zero-offset reflection responses of the structure can be achieved by station au...

The Changning MS6.0 earthquake, occurred on June 17, 2019, is located in the southwestern margin of the Sichuan Basin. Using seismic data recorded on permanent and temporary stations around Changning area, the high-resolution three-dimensional crustal VP, VS, VP/VS models and earthquake locations in Changning-Xingwen area are obtained by using the...

To image high-resolution crustal and upper-mantle structures, ambient noise tomography (ANT) has been widely used on local and regional dense seismic arrays. One of the key steps in ANT is to extract surface-wave group and phase velocity dispersion curves from cross-correlation functions of continuous ambient noise recordings. One traditional way i...

We analyze records of ambient seismicity from Central Chile to investigate mechanisms of tectonic erosion and accretion in an Andean margin. The seismograms were recorded by a temporary network of 39 stations deployed between 32.5°S and 34.0°S from April to November 2017. We employ an automatic earthquake catalogue generator to estimate 8463 P-wave...

Comparable to San Andreas fault in western United States, the Tanlu fault zone (TLFZ) is a large-scale continental tectonic belt in eastern China and has played an important role controlling the regional tectonics and earthquake activity in eastern China. It is known there exists an earthquake gap in the southern segment around Suqian, Jiangsu prov...

To take advantage of complementary strengths of earthquake body wave data and surface wave data from both earthquake and ambient noise sources, we have jointly used them to determine a high-resolution 3D Vs model of the lithosphere in South China by the joint inversion algorithm of Zhang et al. (2014). For body wave data, we assembled P- and S-wave...

With the development of unconventional shale gas in the southern Sichuan Basin, seismicity in the region has increased significantly in recent years. Though the existing sparse regional seismic stations can capture most earthquakes with \begin{document}$ {M}_{\mathrm{L}}\ge 2.5 $\end{document}, a great number of smaller earthquakes are often omitte...

Locating seismic events is a central task for earthquake monitoring. Compared to arrival-based location methods, waveform-based location methods do not require picking phase arrivals and are more suitable for locating seismic events with noisy waveforms. Among waveform-based location methods, one approach is to stack different attributes of P and S...

Detecting subsurface fault structure is important for evaluating potential earthquake risks associated with active faults. In this study, we propose a new method to detect faults using reflected surface waves observed in ambient noise cross correlation functions. Ambient noise tomography using direct surface waves obtained from ambient noise interf...

Xin et al. (2019) presented 3D seismic velocity models (VP and VS) of crust and uppermost mantle of continental China using seismic body-wave travel-time tomography, which are referred to as Unified Seismic Tomography Models for Continental China Lithosphere 1.0 (USTClitho1.0). Compared with previous models of continental China, the VP and VS model...

Plain Language Summary Fault deformation can be characterized by the distribution of seismicity in fault zones. However, failure in the shallow crust is often aseismic due to the velocity strengthening friction behavior of fault zone materials. Isotropic velocity tomography can be used to delineate fault deformation in the aseismic or diagenetic la...

Double seismic zones are commonly observed in the subducting slabs in a global scale,serving as ideal examples for studying the seismogenetic mechanism of the intermediate-depth earthquakes. In this study, we relocate earthquakes and determine seismic velocity models using the double-difference seismic tomography method in the northern Chile subduc...

The unknown onshore extent of megathrust earthquake rupture in the Cascadia subduction zone represents a key uncertainty in earthquake hazard for the Pacific Northwest that is governed by the physical state and mechanical properties of the plate interface. The Cascadia plate interface is segmented into an interseismically locked zone located primar...

Southwest China, located at the southeastern margin of the Tibetan plateau, plays an important role for the plateau growth and its material extrusion. It has complicated tectonic environment and strong seismic activities including the 2008 Wenchuan great earthquake. Numerous geophysical studies have been conducted in southwest China. However, a com...

The stress tensor is an important property for upper crustal studies such as those that involve pore fluids and earthquake hazards. At tectonic plate scale, plate boundary forces and mantle convection are the primary drivers of the stress field. In many local settings (10–100 s of km and <10 km depth) in tectonic plate interiors, we can simplify by...

The Alaska Peninsula section of the Aleutian-Alaska subduction zone exhibits significant along-strike variations in plate coupling, earthquakes, and arc magmatism. Here we use regional and teleseismic data from 1990 to 2018 to investigate intermediate-depth intra-plate seismicity beneath the Alaska Peninsula. The distribution of these events shows...

As the largest fault trending NNE-SSW to NE-SW in the eastern Eurasia Continent, the Tanlu fault zone (TLFZ) extends over 2,400 km within China, roughly from Wuxue, Hubei Province, to Russia. Since the Quaternary period, the TLFZ has been an earthquake-prone area in eastern China where several major earthquakes resulted by tectonic compression occu...

Ambient noise tomography (ANT) has become a routine method to image shear‐wave velocity variations at different scales. However, ANT can only resolve smooth velocity variations and cannot give high‐resolution images of the subsurface discontinuities. Here we propose a novel Transmitted Surface Wave Reverse Time Migration (TSW‐RTM) method to directl...

In recent years, as the amount of seismic data has grown rapidly, it is very important to develop a fast and reliable event detection and association algorithm. Generally, event detection is first performed on individual stations followed by event association through linking phase arrivals to a common event generating them. This study considers ear...