Article
Geochemistry & Geophysics
E. Crowder, N. Rawlinson, D. G. Cornwell, C. Sammarco, E. Galetti, A. Curtis
Summary: The deep crustal structure beneath the North Sea is poorly understood but the mid to lower crust plays important roles in rift initiation and evolution. Ancient tectonic features exist beneath the North Sea, making it an ideal location to investigate regional heterogeneity and rifting interactions.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2021)
Article
Geochemistry & Geophysics
Michael Gunnels, Gurban Yetrimishli, Sabina Kazimova, Eric Sandvol
Summary: Through high-resolution 3-D seismic velocity models and a relocated earthquake catalogue, we observed the seismic activity and velocity structure characteristics in Azerbaijan. The seismic hypocenters cluster into two depth ranges, with intermediate depth seismicity beneath the Kura Basin. Significant variation in seismic velocities was also noted, with the structure of the Kura Basin reflecting that of the Caspian Sea, suggesting a continuation of the Caspian geodynamics into Azerbaijan.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2021)
Article
Geochemistry & Geophysics
Graca Silveira, Nuno Afonso Dias, Sergey Kiselev, Eleonore Stutzmann, Susana Custodio, Martin Schimmel
Summary: This study presents a new high-resolution three-dimensional shear wave velocity model of the crust and uppermost mantle in Portugal. The model contributes to a better understanding of the seismicity and geological structures in Portugal.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2022)
Article
Geochemistry & Geophysics
J. N. Williams, M. J. Werner, K. Goda, L. N. J. Wedmore, R. De Risi, J. Biggs, H. Mdala, Z. Dulanya, A. Fagereng, F. Mphepo, P. Chindandali
Summary: Historical and instrumental earthquake catalogs may not accurately reflect the long-term distribution of seismicity in low strain rate regions. Therefore, probabilistic seismic hazard analysis (PSHA) should consider geologic and geodetic data to incorporate fault-based seismogenic sources. The study explores these issues in the context of a new PSHA for Malawi, which has a thick seismogenic layer and a growing exposure to seismic hazard. The results emphasize the importance of careful fault source modeling in PSHA and the need for new fault-based PSHA in the East Africa Rift.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2023)
Article
Geochemistry & Geophysics
Trond Ryberg, Christian Haberland, Britta Wawerzinek, Manfred Stiller, Klaus Bauer, Alberto Zanetti, Luca Ziberna, Gyoergy Hetenyi, Othmar Muntener, Michael M. Weber, Charlotte M. Krawczyk
Summary: We present new findings from a seismic experiment conducted in the deepest part of the Val Sesia crust-mantle section in the Ivrea-Verbano zone in the Italian Alps. The experiment revealed a tilted, complete section of the continental crust containing gabbros and peridotites. By using inversion methods, a 3D P-wave velocity model was created, showing a sharp velocity change across the Insubric Zone. The prominent feature of the model is a high-velocity body interpreted as peridotite, which challenges previous models and suggests a reevaluation of the dimension of peridotite material in the area.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2023)
Article
Geochemistry & Geophysics
J. Petruska, Z. Eilon
Summary: The East African Rift System provides a unique opportunity to study different stages of rifting. In this study, researchers used various data and inversion algorithms to investigate the shear velocity profiles across the Main Ethiopian Rift and the Ethiopian Plateau. The results revealed slower shear velocities and shallow mantle features in the off-axis region, supporting the notion of off-axis extension in the Ethiopian plateau. These findings have important implications for the understanding of continental breakup in the narrow Main Ethiopian Rift.
GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS
(2022)
Article
Geochemistry & Geophysics
Guoqing Lin, Zhigang Peng, Miguel Neves
Summary: This study presents estimations and comparisons of in situ V-p/V-s ratios and seismicity characteristics for the Parkfield segment of the San Andreas fault in northern California and the San Jacinto Fault Zone and its adjacent regions in southern California. The high-resolution in situ V-p/V-s ratios are found to be more complex than the tomographic V-p/V-s models and are influenced by material properties and fluid contents. The study also observes velocity contrasts between different fault sections and anomalous V-p/V-s variation patterns in southern California. The correlation between similar events and anomalous V-p/V-s ratios supports the role of fluids in repeating earthquakes.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2022)
Article
Multidisciplinary Sciences
Ingo Grevemeyer, Lars H. Ruepke, Jason P. Morgan, Karthik Iyer, Colin W. Devey
Summary: Oceanic transform faults, which were previously believed to be conservative two-dimensional strike-slip boundaries, are revealed to be more complex due to deeper seafloor along the faults than their associated fracture zones. Accretion at intersections between oceanic ridges and transform faults is asymmetric, with outside corners showing shallower relief and more extensive magmatism. This leads to a two-stage process of accretion at transform-fault systems, different from other regions along mid-ocean ridges.
Article
Geosciences, Multidisciplinary
C. Esteve, Y. Liu, I Koulakov, A. J. Schaeffer, P. Audet
Summary: This study investigates the seismic activity of the Canadian Beaufort Sea continental margin and identifies a unique low-velocity anomaly in the crust, potentially associated with crustal thinning and weakening. The findings suggest that the north-south compression in this region is accommodated through slow, aseismic deformation, without necessarily involving subduction initiation.
GEOPHYSICAL RESEARCH LETTERS
(2022)
Article
Geochemistry & Geophysics
Yongsheng Liu, Ping Tong
Summary: This study investigated the seismic anisotropy in the crust of northern California using seismic techniques, revealing the presence of different geological units and parallel fault zones. The results showed significant velocity contrasts, possibly indicating different geological structures and stress states.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2021)
Article
Geochemistry & Geophysics
T. Ryberg, W. H. Geissler, W. Jokat, X. Yuan, T. Fromm, S. Pandey, B. Heit
Summary: The Walvis Ridge is a prominent hotspot track related to the opening of the South Atlantic Ocean. Through seismic experiments and tomography, the study investigates the crustal structure modified by the Tristan hotspot in the landward prolongation of the ridge and in adjacent oceanic basins. The results reveal the structural features of the crust in these areas.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2022)
Article
Geochemistry & Geophysics
S. Rost, G. A. Houseman, A. W. Frederiksen, D. G. Cornwell, M. Kahraman, S. Altuncu Poyraz, U. M. Teoman, D. A. Thompson, N. Turkelli, L. Gulen, M. Utkucu, T. J. Wright
Summary: Research using dense seismic data reveals the subsurface structure of the North Anatolian Fault Zone, with findings showing lateral incoherence of crustal interfaces, contrasting crustal structures on either side of the fault zone, and strong variations in structure both north-south and east-west within the study region. The results suggest the presence of major shear zones throughout the crust and into the lithospheric mantle beneath the fault zone, indicating a strong coupling of strain at these depths.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2021)
Article
Geochemistry & Geophysics
Mahin Jafari, Mahtab Aflaki, Zahra Mousavi, Andrea Walpersdorf, Khalil Motaghi
Summary: The Ganaveh earthquake occurred on April 18, 2021 in the southwest of the Dezful embayment, Iran. It was a mainly compressive event with a magnitude of M-w 5.8. The InSAR coseismic displacement maps showed a maximum surface displacement of 17 cm in the satellite line of sight. The earthquake occurred within the competent layers of the Zagros sedimentary cover, beneath the Gachsaran formation.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2023)
Article
Geochemistry & Geophysics
Yojiro Yamamoto, Dogan Kalafat, Ali Pinar, Narumi Takahashi, Remzi Polat, Yoshiyuki Kaneda, Haluk Ozener
Summary: The study used ocean bottom seismometer observations to assess the location of possible asperities for future large earthquakes, finding that offshore observations are more accurate and can detect more microearthquakes compared to land-based observations. Results from 2014 to 2017 show that the seismic activity pattern along the North Anatolian Fault beneath the Marmara Sea has remained unchanged.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2022)
Article
Geochemistry & Geophysics
I Gaudot, E. Beucler, A. Mocquet, M. Drilleau, M. Haugmard, M. Bonnin, G. Aertgeerts, D. Leparoux
Summary: This study presents a 3-D seismic tomographic model of western France and surrounding regions, revealing the crustal structure in detail. Using an unconventional approach with 55 broad-band seismometers, a V-S model with lateral resolution of 75 km was constructed, providing insights into both shallow and deep crustal features in the area.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2021)
Article
Geochemistry & Geophysics
Sang-Jun Lee, Seongryong Kim, Junkee Rhie, Tae-Seob Kang, YoungHee Kim
Summary: This study used ambient noise data from a temporary seismic network on Jeju Island to image the upper crustal structures. The results showed the presence of layers with negative and positive anisotropy at different depths, which help explain the evolution of the Jeju Island volcanoes.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2021)
Article
Geochemistry & Geophysics
Hyunsun Kang, YoungHee Kim, Junkee Rhie, Tae-Seob Kang, Marco Brenna
Summary: Jeju Island is characterized by a complex magma plumbing system, with deep crustal seismic structure showing variations between different regions, reflecting diverse rock compositions and dynamic processes. The presence of a residual magma plumbing system on the island was revealed through dense seismic data, and the use of robust research methods aids in enhancing our understanding of the island's evolution.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2021)
Article
Geochemistry & Geophysics
Jaeseok Lee, Jung-Hun Song, Seongryong Kim, Junkee Rhie, Seok Goo Song
Summary: This study provides accurate and practical predictions of ground motion for potential large earthquakes using rigorous physics-based modeling and wave propagation simulations. It suggests the possibility of damaging earthquakes in the southeastern region of the Korean Peninsula. By simulating multiple earthquake scenarios and comparing them with observed data, the study accurately reproduces the spatial distribution of ground motion, as well as surface-wave radiation, rupture directivity, and amplifications from 3D wave propagation.
BULLETIN OF THE SEISMOLOGICAL SOCIETY OF AMERICA
(2022)
Article
Geochemistry & Geophysics
Sungho Lee, Arushi Saxena, Jung-Hun Song, Junkee Rhie, Eunseo Choi
Summary: This study aims to understand the stress field of the Korean Peninsula using numerical simulations and seismic tomography. The results suggest that crustal and upper-mantle heterogeneities are responsible for the seismic activity in the region. Compressional stress and mantle heterogeneities control the seismicity in the western area, while a correlation is found between relatively thin lithosphere and strong upper-mantle upwelling with the seismic activity in the eastern area.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2022)
Article
Geosciences, Multidisciplinary
Min-Seong Seo, Young Oh Son, YoungHee Kim, Tae-Seob Kang, Junkee Rhie, Kwang-Hee Kim, Jin-Han Ree
Summary: In this study, we investigated the misalignment of 200 temporary broadband seismometers based on the polarization of P waves. We estimated time-dependent misorientation angles of the seismometers from June 2018 to March 2021 with small uncertainty. Our methods proved to be reliable in detecting temporal changes in misorientation angles and the results can serve as essential metadata for further seismological researches utilizing the dense array data.
GEOSCIENCES JOURNAL
(2022)
Article
Geosciences, Multidisciplinary
Yunsun Jung, Jeong-Ung Woo, Junkee Rhie
Summary: This study demonstrates that using a 3D velocity model improves the accuracy of hypocenter determination compared to a 1D model, particularly in the presence of complex basin geometry and crustal thickness heterogeneity.
GEOSCIENCES JOURNAL
(2022)
Article
Geosciences, Multidisciplinary
Tae-Seob Kang, ChangHwan Kong, Hyun Jae Yoo
Summary: The characteristics of man-made signals were identified by analyzing seismic records from a temporary seismograph station installed in Terra Nova Bay, Antarctica. The study showed that these records can be used to investigate the causes of man-made signals.
JOURNAL OF THE GEOLOGICAL SOCIETY OF KOREA
(2022)
Article
Geosciences, Multidisciplinary
Jung-Hun Song, Seongryong Kim, Junkee Rhie, Donghee Park
Summary: This study demonstrates the effectiveness of using three-dimensional velocity structures to accurately constrain earthquake source parameters and resulting seismic wave propagation in a region with complex continental margin structures and sedimentary basins.
FRONTIERS IN EARTH SCIENCE
(2022)
Article
Geochemistry & Geophysics
Eunbyeol Cho, Jeong-Ung Woo, Junkee Rhie, Tae-Seob Kang, So -Young Baag
Summary: The Mw 5.5 earthquake in Pohang, South Korea on November 15, 2017, known as a runaway earthquake caused by fluid injection, was investigated for spatiotemporal slip distributions using finite-fault inversion. The rupture process was divided into three steps, with slip first propagating southwest from the hypocenter, then occurring in both southwest and northeast parts, and finally happening around the edge of the fault plane. The seismic moment released in each step was approximately 6%, 59%, and 35%, respectively. The study provides insights into the seismic source physics and mechanisms of the Pohang earthquake by analyzing the slip history, directivity, and stress drop distribution on the fault plane.
BULLETIN OF THE SEISMOLOGICAL SOCIETY OF AMERICA
(2023)
Article
Geochemistry & Geophysics
Sungho Lee, Jeong-Ung Woo, Junkee Rhie
Summary: The 2017 M-w 5.5 Pohang earthquake near an enhanced geothermal system site generated numerous aftershocks, including a M-w 4.6 earthquake occurring 87 days later. This study utilized poroelastic modeling to evaluate the contribution of pore pressure variations on the spatiotemporal distribution of aftershocks. The results highlight the importance of pore pressure in triggering and influencing the decay of aftershocks.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2023)
Article
Geochemistry & Geophysics
Hyejin Park, Tae-Seob Kang, Hyun Jae Yoo, Dabeen Heo
Summary: The 2016 offshore Ulsan earthquake occurred in the southwestern margin of the Ulleung Basin, which had experienced extensional tectonic forces followed by compressional stress. The earthquake was likely caused by reactivated geological faults, and understanding its mechanisms is important for assessing the seismic hazard potential of the region. The earthquake sequence in 2016 was likely a result of the reactivation of faults formed during the Miocene, with faults in the E-W to NW-SE directions dominantly responsible for the current seismic activity in the southwestern Ulleung Basin.
MARINE GEOPHYSICAL RESEARCH
(2023)
Article
Geochemistry & Geophysics
Sungho Lee, Jung-Hun Song, Dabeen Heo, Junkee Rhie, Tae-Seob Kang, Eunseo Choi, Younghee Kim, Kwang-Hee Kim, Jin-Han Ree
Summary: Using seismic data and a seismic network, this study constructed a 3-D P-wave velocity model of the crust and upper mantle in the southeastern Korean Peninsula (SeKP) for the first time. The model revealed three distinct velocity patterns at different depths, suggesting the presence of major driving forces that promote seismic and hydrothermal activities in the region.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2023)