Article
Geosciences, Multidisciplinary
David R. R. Shelly, Robert J. J. Skoumal, Jeanne L. L. Hardebeck
Summary: In August 2020, a seismic sequence began in the Maacama fault zone in northern California, leading to questions about its connection with a larger fault. Through various seismic analysis techniques, including event detection, relocation, and focal mechanisms, the researchers investigated the faulting geometry and its impact on seismic activity. They discovered that the sequence originated from a right-lateral fault, likely a section of the Maacama Fault, but also activated numerous left-lateral conjugate faults, forming a fracture mesh consistent with fluid-induced faulting and earthquake swarms seen elsewhere.
GEOPHYSICAL RESEARCH LETTERS
(2023)
Article
Multidisciplinary Sciences
Tao Wu, Maurice A. Tivey, Chunhui Tao, Jinhui Zhang, Fei Zhou, Yunlong Liu
Summary: Magmatic and tectonic processes play important roles in discontinuous crustal accretion and hydrothermal circulation. The study reports a multi-scale magnetic survey providing insights into the evolution of a detachment faulting system hosting hydrothermal activity.
NATURE COMMUNICATIONS
(2021)
Article
Geosciences, Multidisciplinary
Zhengyi Zhang, Dongdong Dong, Weidong Sun, Guangxu Zhang
Summary: The latest multichannel seismic data from the Yap subduction zone reveals the formation mechanism of the Caroline Ridge fault system, indicating the presence of varied faults and orientations due to different faulting and rifting processes. Variations in topography and sedimentary characteristics in different regions suggest that the distinct fault mechanisms and rift processes contribute to the geological differences between the North and South Caroline Ridge.
Article
Geochemistry & Geophysics
R. Parnell-Turner, D. K. Smith, R. P. Dziak
Summary: This article presents a catalog of T-phase events in the equatorial Atlantic ocean, including the Mid-Atlantic Ridge and transform faults. By studying seismic activity, insights can be gained into the processes of crustal accretion and transform fault slip. It was observed that areas with asymmetric spreading have higher seismicity rates and the majority of hydrothermal vents occur in these areas. Additionally, aseismic patches were found on almost all equatorial Atlantic transform faults.
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(2022)
Article
Multidisciplinary Sciences
Jie Chen, Wayne C. Crawford, Mathilde Cannat
Summary: Oceanic detachment faults in the Southwest Indian Ridge at 64 degrees 30'E accommodate plate divergence and have smooth seafloor. Microseismicity data shows that the axial brittle lithosphere is 15 km thick under the nearly-amagmatic smooth seafloor, which is similar to volcanic seafloor or more magmatic detachment systems. The hanging-wall seismicity at nearly-amagmatic flip-flop detachment systems is significantly higher than at more magmatic detachments of slow-ultraslow ridges.
NATURE COMMUNICATIONS
(2023)
Article
Geochemistry & Geophysics
Yuqi Huang, Max Moorkamp, Ji Gao, Haijiang Zhang
Summary: On 3 August 2014, a destructive earthquake occurred in Ludian, Yunan, China, resulting in significant casualties. To understand the seismogenic structure of this earthquake, the study developed a three-dimensional joint inversion algorithm combining magnetotelluric data and seismic body wave arrival times. The models generated from this algorithm revealed low Vp/Vs ratios and resistivity in the upper crust of the main shock zone, as well as the presence of cracks/fractures, fluids, and high quartz contents. These findings suggest that fluids and high quartz contents may have played a role in promoting the Ludian earthquake. This study provides new evidence on how crustal properties influence the genesis of moderate to large earthquakes.
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(2023)
Article
Environmental Sciences
Davide Zaccagnino, Carlo Doglioni
Summary: This study found that earthquakes on thrust faults have a higher double couple component compared to earthquakes on strike-slip and normal faults, which may be due to the more mature fault zone structure. This finding has important implications for seismic forecasting and magnitude estimation.
COMMUNICATIONS EARTH & ENVIRONMENT
(2022)
Article
Environmental Sciences
Xiaoge Liu, Lei Xie, Yujiang Li, Bingquan Han, Zhidan Chen, Wenbin Xu
Summary: This study used InSAR observations to constrain the seismic fault geometry and distributed fault slip within the Nyainrong microcontinent, and inverted the stress regimes surrounding it using regional focal mechanism solutions. The results showed dominant normal faulting stress regime to the northeast and dominant strike-slip stress regime to the southwest, highlighting the significance of the ancient microcontinent in the tectonic evolution of the Tibetan Plateau.
Article
Geosciences, Multidisciplinary
Rajkumar, Sanjay K. Prajapati, Sanjit K. Pal, H. N. Srivastava
Summary: This study determines the focal depths of earthquakes in Northeast India from 2011 to 2018 using depth phases and point source waveform inversion. The results indicate that the seismogenic depths in all tectonic zones are shallow, ranging from 10 to 20 km.
Article
Geosciences, Multidisciplinary
Peng Guo, Satish C. Singh, Venkata A. Vaddineni, Ingo Grevemeyer, Erdinc Saygin
Summary: Oceanic crust is formed through a combination of magmatic and tectonic processes, with the formation of the lower crust still under debate. Seismic data from young crust formed at the Mid-Atlantic Ridge reveal alternating layers of high and low velocities, with the uppermost low-velocity layer associated with hydrothermal alteration. The layering supports the intrusion of melt as sills at different depths to form the lower crust, indicating a stable process of lower crustal accretion.
Article
Geochemistry & Geophysics
Charu Kamra, Sumer Chopra, R. B. S. Yadav
Summary: The study determines the focal mechanism solutions and source parameters of recent earthquakes in the northeastern region of India. The tectonics in the region are complex due to compressional forces from all sides caused by the collision of plates. The focal mechanisms are used to understand the stress field in the region, revealing different tectonic regimes in different subregions. The stress drop of the earthquakes is found to be dependent on the focal mechanism type, seismic moment, and hypocentral depths, and the results are compared with another region in western India.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2023)
Article
Geosciences, Multidisciplinary
Wangwang Gu, Sidao Ni, Shuofan Wang, Baolong Zhang, Xinglin Lei, Risheng Chu, Aizhi Guo, Qiang Shen, Hansheng Wang, Liming Jiang, Minhan Sheng, Jiajun Chong
Summary: Although the Sichuan basin is considered to have low seismic activity, the Suining M5.0 earthquake in 2010 caused significant damage. The shallow earthquake occurred near the center of the basin and the causative fault was previously unidentified. Through seismic waveform data and InSAR data, it was determined that the earthquake had a shallow depth and occurred on a high angle thrust fault dipping to the southeast. The earthquake may have been triggered by the migration of high-pressure fluid from an underlying gas reservoir.
SCIENCE CHINA-EARTH SCIENCES
(2023)
Article
Geochemistry & Geophysics
Yu Jiang, Sergey V. Samsonov, Pablo J. Gonzalez
Summary: Improved imaging of fault slip is crucial for understanding earthquakes and faulting. By introducing a new regularization method, we successfully recovered complex slip propagation patterns and estimated the spatio-temporal evolution of fault slip. Applying the method to a seismic swarm, we found that aseismic slip played a significant role and the slip rates were consistent with slow earthquake processes.
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(2022)
Article
Geochemistry & Geophysics
Osamu Sandanbata, Hiroo Kanamori, Luis Rivera, Zhongwen Zhan, Shingo Watada, Kenji Satake
Summary: The method of estimating ring-fault parameters based on MT solutions obtained from long-period seismic records is proven to be effective, enabling the examination of the kinematics and structures below active volcanoes with ring faults globally.
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(2021)
Article
Geology
Zhengyi Zhang, Dongdong Dong, Weidong Sun, Guangxu Zhang, Yongliang Bai
Summary: The study investigates the rift activity and volcanic effects on the crust in Caroline Ridge, presenting a typical case of plateau evolution. Rifts and seamount eruptions are shown to deform the strata, with lava flows and sedimentary layers being faulted by normal fault sets. The formation of Caroline Ridge is proposed to be caused by lateral extension of subaerial lava flows from hotspot magmatism, with initial rifting occurring during the Early-Middle Miocene.
INTERNATIONAL GEOLOGY REVIEW
(2021)