Article
Geochemistry & Geophysics
Karen Luttrell, Jeanne Hardebeck
Summary: Studies comparing crustal stress orientation from earthquake focal mechanisms and borehole breakouts in the Los Angeles region show good agreement when sampling basement or mid-basin stress, but only acceptable agreement along sedimentary basin margins when focal mechanisms are limited to shallow and close earthquakes. Results suggest short-length scale stress heterogeneity in basins, but more homogeneous stress state within basement rock. These findings imply distinct regimes for the use of each type of stress indicator.
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(2021)
Article
Geochemistry & Geophysics
Ahad Nouri, Behnam Rahimi, Vaclav Vavrycuk, Farzin Ghaemi
Summary: We analyzed the stress field in the Zagros fold-and-thrust belt (ZFTB) by studying 898 mainshock focal mechanisms between 1956 and 2021. The results showed heterogeneous crustal stress with variations in SHmax orientation and stress ratio. The study identified three distinct domains (northern, central, and southern) with different tectonic regimes (wrench, compressional, and wrench-compressional to compressional). Convergence between the Arabian and Iranian plates was determined as the primary factor influencing deformation and seismicity in the ZFTB zone.
Article
Geochemistry & Geophysics
Takahiko Uchide, Takahiro Shiina, Kazutoshi Imanishi
Summary: Crustal stress is an important parameter for understanding tectonics and large earthquakes. In this study, we investigated the crustal stress orientations in Japan using focal mechanism solutions of small earthquakes. The results reveal an east-west compressional stress for the Japanese islands, with areas along the Pacific coast of northeast Japan showing east-west extensional stress. The study also identified stress anomalies near geological borders and Cape Shionomisaki in the Kii peninsula.
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(2022)
Article
Geochemistry & Geophysics
Mohammad Reza Sheikholeslami, Parisa Mobayen, Hamid Reza Javadi, Mohammad R. Ghassemi
Summary: This paper presents the latest data on the stress pattern and tectonic regime in Central Iran, based on focal mechanism data collected from GCMT, HRVD, and ISC. The study reveals a dominant N029 degrees E maximum horizontal compressive stress direction in the region, indicating a general compressive tectonic regime.
Article
Energy & Fuels
Ye-Jun Jin, Ling-Dong Meng, Ding-You Lyu, Xiao-Fei Fu, Jiang-Bo Huang, Si-Jia Cao, Jian-Da Li
Summary: The hazards of fault reactivation caused by fluid injection are a growing concern. Traditional evaluation methods of fault stability are likely to underestimate the risk in fault segments with a high clay content. This study establishes an extended evaluation method of fault stability that incorporates the heterogeneity in friction strength caused by variation in the clay content within the fault zone. The results highlight the importance of incorporating friction strength heterogeneity in the process of fault evaluation, as it can affect the assessment of high-risk fault segments.
Article
Geochemistry & Geophysics
Alexandre P. Plourde, Mladen R. Nedimovic
Summary: The study examines earthquake activity in the Lower St. Lawrence Seismic Zone, using various methods to estimate focal mechanisms and reconstruct the state of tectonic stress. Results suggest the presence of faults capable of generating sizable earthquakes, but further research is needed due to uncertainties in hypocenter and focal mechanism estimations.
SEISMOLOGICAL RESEARCH LETTERS
(2021)
Article
Geochemistry & Geophysics
Wenhuan Kuang, Congcong Yuan, Jie Zhang, Wei Zhang
Summary: Earthquake focal mechanisms are important for understanding faulting geometry and stress distributions. Existing approaches are limited by uncertainties in velocity models. This study proposes a relative focal mechanism inversion method that utilizes a well-constrained primary event. Testing on synthetic and real earthquake data demonstrates the robustness and improved consistency of the proposed method. It provides reliable earthquake focal mechanisms for the investigation of the earthquake process.
SEISMOLOGICAL RESEARCH LETTERS
(2023)
Article
Geochemistry & Geophysics
Mohammad Ali Khanban, Mehrdad Pakzad, Noorbakhsh Mirzaei, Ali Moradi, Mahmoud Mehramuz
Summary: In this study, the Iterative Joint Inversion method was used to determine the principal stress axes in the Zagros continental collision zone of Iran, revealing the characteristics of compressional stress direction, stress regime, and shape ratio. The results showed a gradual counterclockwise rotation of the compressional stress axis, which is in accordance with the convergence between the Arabian plate and Iranian micro-continent.
JOURNAL OF GEODYNAMICS
(2021)
Article
Geosciences, Multidisciplinary
Gabor Tari, Chris Connors, Joan Flinch, James Granath, Paolo Pace, Konstantin Sobornov, Juan Ignacio Soto
Summary: The frequency of positive or negative structural inversions differs, with positive inversions being more common and receiving more attention in the petroleum industry and academia. However, negative inversions may produce more traps in the internal parts of thrust fold belts. The lack of case studies on negative inversion compared to positive inversion may be due to non-observation in the subsurface or fundamental structural differences between the two processes.
MARINE AND PETROLEUM GEOLOGY
(2023)
Article
Engineering, Geological
Kunbo Wu, Junpeng Zou, Yu-Yong Jiao, Xiufeng Zhang, Chao Wang
Summary: Strong seisms triggered during deep coal mining pose a serious threat to the safety of underground miners and ground residents. Investigating focal mechanisms and source parameters of seisms is essential for understanding rock fracturing and rupture scale. However, such research is lacking in deep mines. This study analyzed over 11,000 seismic events in Dongtan Coal Mine and proposed a new criterion for determining rock fracture type. The formation mechanisms of strong seisms in mines were categorized and the correlation of source parameters was revealed.
ROCK MECHANICS AND ROCK ENGINEERING
(2023)
Article
Geochemistry & Geophysics
Amandine Amemoutou, Patricia Martinez-Garzon, Grzegorz Kwiatek, Justin L. Rubinstein, Marco Bohnhoff
Summary: The significant increase in seismicity rates in the USA over the past 10 years is attributed to the injection of wastewater from oil and gas production. A study on induced earthquakes in southern Kansas reveals that their source mechanisms are related to injection activity and local stress fields. The orientation of fault geometries in relation to the stress field show that small stress perturbations caused by water injection could lead to failure.
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(2021)
Article
Geochemistry & Geophysics
Ahmed Zeeshan Shaukat, Mohammad Tahir, Tahir Iqbal, Talat Iqbal, Muhammad Ali Shah
Summary: Moment tensor inversion was used to analyze a moderate magnitude earthquake near Khuzdar, Pakistan in May 2022. The faulting style suggests a possible association with the Ornach-Nal strike-slip fault. Stress inversion was performed to determine the principal stress axis, which indicates the oblique convergence of the Indian and Arabian plates beneath Eurasian. The presence of stress loaded asperities along the fault system was observed before the earthquake.
PURE AND APPLIED GEOPHYSICS
(2023)
Article
Geochemistry & Geophysics
Shihuai Zhang, Xiaodong Ma, Kai Broker, Rutger van Limborgh, Quinn Wenning, Marian Hertrich, Domenico Giardini
Summary: Characterizing the in situ stress state within fault zones is challenging but essential for understanding earthquake processes, fluid flow, and subsurface engineering. In this study, an array of inclined boreholes in the Bedretto Underground Laboratory in the Swiss Alps was used to observe the breakouts and identify natural geologic structures intersecting the fault zone. By analyzing the breakout rotations and utilizing the stress field around the boreholes, the stress variations within and outside the fault zone were estimated. The results provide insights into the spatial relationship between stress state and fault structure.
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(2023)
Article
Chemistry, Multidisciplinary
Aitang Li, Chaodi Xie, Yingfeng Ji, Weiling Zhu, Yan Xu, Guangming Wang, Xiaoyan Zhao
Summary: On June 12, 2021, a magnitude 5.0 earthquake occurred in Yingjiang, Yunnan, which is prone to seismic activity due to plate collision. Researchers inverted the regional stress field of Yingjiang using the focal mechanisms of 187 historical earthquakes in the area to explore the mechanism of this earthquake. The results showed strike-slip-type stress accumulation in Yingjiang with a principal compressive stress axis direction-oriented NNE-SSW. The study also estimated the fault slip tendency, which indicated enhanced stress coupling in seismogenic faults within specific strike and dip ranges. The distribution of the aftershock sequence is believed to be correlated with local fluid migration and controlled by ruptures of stressed fault systems induced by hydrated rock near the source region. This study provides valuable insights into potential earthquake risks in the region.
APPLIED SCIENCES-BASEL
(2023)
Article
Geochemistry & Geophysics
Yang YiHai, Zhang XueMei, Hua Qian, Su LiNa, Feng ChengJun, Qiu Yurong, Liang ChunTao, Su JinRong, Gu YunHe, Jin ZhaoDi, Zhang YuanYuan, Guan Xin
Summary: Through sources of seismic mechanisms and analysis of tectonic stress fields, this study reveals the clear segmentation characteristics of the Longmenshan fault in terms of faulting types, fault plane structures, and tectonic stress fields.
CHINESE JOURNAL OF GEOPHYSICS-CHINESE EDITION
(2021)