Journal of Geophysical Research: Solid Earth最新文献

{"title":"Phases of Magmatism and Tectonics Along the Madagascar-Comoros Volcanic Chain, and Synchronous Changes in the Kinematics of the Lwandle and Somalia Plates","authors":"Anaïs Rusquet, Vincent Famin, Laurent Michon, Xavier Quidelleur, François Nauret, Martin Danišík, Gilles Ruffet, Carole Berthod, Sidonie Revillon, Patrick Bachèlery, Isabelle Thinon, Anne Lemoine, Sylvie Leroy, Sébastien Zaragosi, Simon Thivet, Julien Bernard, Loraine Gourbet, Etienne Médard, Alix Toulier","doi":"10.1029/2024jb029488","DOIUrl":"https://doi.org/10.1029/2024jb029488","url":null,"abstract":"This paper aims to solve the longstanding debate on the origin of the Comoros volcanic archipelago (Mozambique Channel, Indian Ocean) concerning whether it represents a hotspot trail or a boundary between the Lwandle and Somalia plates in possible connection with the East African Rift System (EARS). To achieve this goal, we analyzed rock samples from recently discovered and previously uninvestigated volcanoes and edifices by means of geochemistry and geochronology. Major-trace element analyses and radiometric dating (⁴⁰Ar/³⁹Ar, K-Ar, and (U-Th)/He) allow us to identify a widespread phase of Comorian volcanism initiated at 9–8 Ma, involving the Zélée, Geyser, and Leven banks, three atolls east of the Comoros. Another tectono-magmatic phase initiated at 2.5 Ma led to a N-S widening of seamount volcanism, and to the progressive development of en-échelon NW-SE structures. With this new addition of atolls and seamounts, the Comoros Archipelago becomes a ∼700 km-long, ∼200 km-wide E-W chain extending from the Cenozoic volcanoes of Madagascar to the EARS. The reactivation of this chain at 9–8 and 2.5 Ma coincides with abrupt changes in the motion of the Somalia plate relative to the Lwandle plate, and with plate boundary modifications. The en-échelon reorganization of structures also matches the kinematic evolution of Somalia relative to Lwandle, from transtension (>3 Ma) to pure dextral slip (≤3 Ma) in the northern Mozambique Channel. We conclude that the Madagascar-Comoros volcanic chain is a branch of the EARS and a plate boundary, further strengthening the link between magmatism and the Rovuma-Lwandle-Somalia plate kinematics.","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"11 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142911874","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Isolation of Primary Remanent Magnetization From Himalayan Rocks: Insights From Partially Remagnetized Upper Cretaceous Oceanic Red Beds in Southern Tibet, China","authors":"Jie Yuan, Zhaoxia Jiang, Wentao Huang, Caicai Liu, Thubtan Tsering, Shuai Zhang, Kaixian Qi, Zijuan Yang, Zhongshan Shen, Shuhui Cai, Shuangchi Liu, Huafeng Qin, Chunxia Zhang, Zhenyu Yang","doi":"10.1029/2024jb029750","DOIUrl":"https://doi.org/10.1029/2024jb029750","url":null,"abstract":"Oceanic red beds, preserving primary depositional remanent magnetization, play a key role in reconstructing the Tethyan paleogeography. However, partial remagnetization caused by chemical processes could be pervasive in these rocks, leading to flawed reconstructions, and thus, differentiating secondary and primary remanences is important. In this paper, we conduct multiple X-ray diffraction, petrographic, diffuse reflectance spectroscopy, and rock magnetic analyses on the Upper Cretaceous oceanic red beds (CORBs) from the Cailangba section in the Gyangze region of the Tethyan Himalaya. Our results reveal that the CORBs contain coarse-grained detrital hematite with a narrow coercivity distribution, as well as fine-grained authigenic hematite with a broad coercivity distribution. The coarse-grained population is mainly composed of >400 nm hematite grains and unblocks close to the Néel temperature (675°C), consistent with a detrital origin. In contrast, the fine-grained population is mainly composed of <30−400 nm hematite grains and progressively unblocks below 650°C, consistent with a chemical (authigenic) origin. In addition to these two populations of hematite, a small amount of goethite, unblocking below 120°C, is detected. Due to the distinct unblocking temperature spectra of these two populations of hematite, isolating the primary detrital remanence of the coarse-grained hematite from the chemical remanence of the fine-grained hematite in the CORBs through high-resolution thermal demagnetization treatment is feasible. This study lends confidence to the paleomagnetic studies of these oceanic red beds in Tethyan paleogeographic reconstructions.","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"32 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142911877","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Influence of Initial Slab Dip, Plate Interface Coupling, and Nonlinear Rheology on Dynamic Weakening at the Lithosphere-Asthenosphere Boundary","authors":"Vivek Bhavsar, Margarete Jadamec, Matthew Knepley","doi":"10.1029/2023jb028423","DOIUrl":"https://doi.org/10.1029/2023jb028423","url":null,"abstract":"The slab dip and long-term coupling along the plate interface can vary both between and within subduction zones. However, how the initial slab dip and resistance at the plate interface affect the dynamic viscous resistance of the asthenosphere at the lithosphere-asthenosphere boundary (LAB) is less understood. This paper presents two-dimensional (2D) visco-plastic models that examine the surface plate velocity and dynamic weakening of the asthenosphere as a function of three values of initial slab dip (<span data-altimg=\"/cms/asset/d5ad0044-7936-4d93-9984-f0fd66e0b010/jgrb57054-math-0001.png\"></span><math altimg=\"urn:x-wiley:21699313:media:jgrb57054:jgrb57054-math-0001\" display=\"inline\" location=\"graphic/jgrb57054-math-0001.png\">\u0000<semantics>\u0000<mrow>\u0000<mn>3</mn>\u0000<msup>\u0000<mn>0</mn>\u0000<mi>o</mi>\u0000</msup>\u0000</mrow>\u0000$3{0}^{o}$</annotation>\u0000</semantics></math>, <span data-altimg=\"/cms/asset/fb4b97d8-c90b-43f3-bdc4-5e316a9b4fd5/jgrb57054-math-0002.png\"></span><math altimg=\"urn:x-wiley:21699313:media:jgrb57054:jgrb57054-math-0002\" display=\"inline\" location=\"graphic/jgrb57054-math-0002.png\">\u0000<semantics>\u0000<mrow>\u0000<mn>4</mn>\u0000<msup>\u0000<mn>5</mn>\u0000<mi>o</mi>\u0000</msup>\u0000</mrow>\u0000$4{5}^{o}$</annotation>\u0000</semantics></math>, <span data-altimg=\"/cms/asset/9ad95318-2b84-46ef-b2cf-120dba2445ed/jgrb57054-math-0003.png\"></span><math altimg=\"urn:x-wiley:21699313:media:jgrb57054:jgrb57054-math-0003\" display=\"inline\" location=\"graphic/jgrb57054-math-0003.png\">\u0000<semantics>\u0000<mrow>\u0000<mn>6</mn>\u0000<msup>\u0000<mn>0</mn>\u0000<mi>o</mi>\u0000</msup>\u0000</mrow>\u0000$6{0}^{o}$</annotation>\u0000</semantics></math>) and six upper bounds on the plate interface coupling (<span data-altimg=\"/cms/asset/b6debda3-17be-452a-8660-9e31c361d1b5/jgrb57054-math-0004.png\"></span><math altimg=\"urn:x-wiley:21699313:media:jgrb57054:jgrb57054-math-0004\" display=\"inline\" location=\"graphic/jgrb57054-math-0004.png\">\u0000<semantics>\u0000<mrow>\u0000<mn>3.1</mn>\u0000<mo>×</mo>\u0000<mn>1</mn>\u0000<msup>\u0000<mn>0</mn>\u0000<mn>20</mn>\u0000</msup>\u0000</mrow>\u0000$3.1times 1{0}^{20}$</annotation>\u0000</semantics></math>, <span data-altimg=\"/cms/asset/833427c2-8770-49a4-9814-6e6fe2d2ac67/jgrb57054-math-0005.png\"></span><math altimg=\"urn:x-wiley:21699313:media:jgrb57054:jgrb57054-math-0005\" display=\"inline\" location=\"graphic/jgrb57054-math-0005.png\">\u0000<semantics>\u0000<mrow>\u0000<mn>1</mn>\u0000<mo>×</mo>\u0000<mn>1</mn>\u0000<msup>\u0000<mn>0</mn>\u0000<mn>21</mn>\u0000</msup>\u0000</mrow>\u0000$1times 1{0}^{21}$</annotation>\u0000</semantics></math>, <span data-altimg=\"/cms/asset/e1202410-e96b-447e-a0a6-c1a0879f14e6/jgrb57054-math-0006.png\"></span><math altimg=\"urn:x-wiley:21699313:media:jgrb57054:jgrb57054-math-0006\" display=\"inline\" location=\"graphic/jgrb57054-math-0006.png\">\u0000<semantics>\u0000<mrow>\u0000<mn>3.1</mn>\u0000<mo>×</mo>\u0000<mn>1</mn>\u0000<msup>\u0000<mn>0</mn>\u0000<mn>21</mn>\u0000</msup>\u0000</mrow>\u0000$3.1times 1{0}^{21}$</annotation>\u0000</semantics></math>, <span data-altimg=\"/cms/asset/3db4f597-2f1d-42c9-8de6-0630ef04c17e/jgrb57054-math-0007.png\"></span><math altimg=\"urn:x-wiley:21699313:media:jgrb57054:jgrb57054-math-0007\" display=\"inline\" location=\"graphic/jgrb57054-math-0007","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"24 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142911875","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Understanding the Seismic Signature of Transtensional Opening in the Reykjanes Peninsula Rift Zone, SW Iceland","authors":"Pınar Büyükakpınar, Marius Paul Isken, Sebastian Heimann, Torsten Dahm, Daniela Kühn, Juliane Starke, José Ángel López Comino, Simone Cesca, Jana Doubravová, Egill Árni Gudnason, Thorbjörg Ágústsdóttir","doi":"10.1029/2024jb029566","DOIUrl":"https://doi.org/10.1029/2024jb029566","url":null,"abstract":"We analyze seismicity and centroid moment tensors (CMTs) on the Reykjanes Peninsula, Iceland, during the early phase of a widespread unrest period that led to multiple fissure eruptions between 2021 and 2024. We use a dense temporary seismic array, together with fiber-optic distributed acoustic sensing data, and incorporate first-motion polarities into the CMT inversion to improve accuracy, generating a total of 300 robust CMT solutions for magnitudes <span data-altimg=\"/cms/asset/513c34cf-f751-4774-90d1-41ec2c4bfbcd/jgrb57080-math-0001.png\"></span><mjx-container ctxtmenu_counter=\"237\" ctxtmenu_oldtabindex=\"1\" jax=\"CHTML\" role=\"application\" sre-explorer- style=\"font-size: 103%; position: relative;\" tabindex=\"0\"><mjx-math aria-hidden=\"true\" location=\"graphic/jgrb57080-math-0001.png\"><mjx-semantics><mjx-mrow data-semantic-children=\"5,3\" data-semantic-content=\"2\" data-semantic- data-semantic-role=\"inequality\" data-semantic-speech=\"upper M w greater than 2.5\" data-semantic-type=\"relseq\"><mjx-mrow data-semantic-annotation=\"clearspeak:simple;clearspeak:unit\" data-semantic-children=\"0,1\" data-semantic-content=\"4\" data-semantic- data-semantic-parent=\"6\" data-semantic-role=\"implicit\" data-semantic-type=\"infixop\"><mjx-mi data-semantic-annotation=\"clearspeak:simple\" data-semantic-font=\"italic\" data-semantic- data-semantic-parent=\"5\" data-semantic-role=\"latinletter\" data-semantic-type=\"identifier\"><mjx-c></mjx-c></mjx-mi><mjx-mo data-semantic-added=\"true\" data-semantic- data-semantic-operator=\"infixop,⁢\" data-semantic-parent=\"5\" data-semantic-role=\"multiplication\" data-semantic-type=\"operator\" style=\"margin-left: 0.056em; margin-right: 0.056em;\"><mjx-c></mjx-c></mjx-mo><mjx-mi data-semantic-annotation=\"clearspeak:simple\" data-semantic-font=\"italic\" data-semantic- data-semantic-parent=\"5\" data-semantic-role=\"latinletter\" data-semantic-type=\"identifier\"><mjx-c></mjx-c></mjx-mi></mjx-mrow><mjx-mo data-semantic- data-semantic-operator=\"relseq,>\" data-semantic-parent=\"6\" data-semantic-role=\"inequality\" data-semantic-type=\"relation\" rspace=\"5\" space=\"5\"><mjx-c></mjx-c></mjx-mo><mjx-mn data-semantic-annotation=\"clearspeak:simple\" data-semantic-font=\"normal\" data-semantic- data-semantic-parent=\"6\" data-semantic-role=\"float\" data-semantic-type=\"number\"><mjx-c></mjx-c><mjx-c></mjx-c><mjx-c></mjx-c></mjx-mn></mjx-mrow></mjx-semantics></mjx-math><mjx-assistive-mml display=\"inline\" unselectable=\"on\"><math altimg=\"urn:x-wiley:21699313:media:jgrb57080:jgrb57080-math-0001\" display=\"inline\" location=\"graphic/jgrb57080-math-0001.png\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><semantics><mrow data-semantic-=\"\" data-semantic-children=\"5,3\" data-semantic-content=\"2\" data-semantic-role=\"inequality\" data-semantic-speech=\"upper M w greater than 2.5\" data-semantic-type=\"relseq\"><mrow data-semantic-=\"\" data-semantic-annotation=\"clearspeak:simple;clearspeak:unit\" data-semantic-children=\"0,1\" data-semantic-content=\"4\" data-semantic-parent=\"6\" data-semantic-role=\"implicit\" data-sema","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"93 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142905417","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Three-Dimensional Unstructured Magnetization Vector Inversion and Modeling of Planetary Equivalent Toroidal Currents for Earth’s Magnetic Field Analysis","authors":"Boxin Zuo, Xiangyun Hu, Lizhe Wang, Yi Cai, Mason Andrew Kass","doi":"10.1029/2024jb029224","DOIUrl":"https://doi.org/10.1029/2024jb029224","url":null,"abstract":"This study introduces a pioneering methodology for modeling the Earth’s geomagnetic field, departing from traditional reliance on current loops by employing a three-dimensional (3-D) geometric equivalent toroidal current source. We propose a 3-D unstructured magnetization vector inversion method aimed at inverting the geomagnetic vector field data set to construct an equivalent magnetization source. Subsequently, this constructed source is utilized to solve for the distribution of equivalent toroidal currents. Our objective is to elucidate and analyze potential distributions of toroidal currents within the core space. Diverging from conventional practices that estimate only seven parameters for a current loop, our research undertakes the inversion of millions of current parameters across the entire 3-D core space. This strategy eliminates the need for presuppositions regarding the current’s positions or its topological characteristics, significantly enhancing our capability to depict the possible geometry of toroidal currents. These advancements show considerable promise for modeling the geomagnetic field with high precision, transforming complex equivalent sources into more comprehensible forms, and offering profound implications for our understanding of Earth’s magnetic environment.","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"174 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142905358","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Interseismic Uplift of Anticlines Above the Rakhine-Bangladesh Megathrust From ALOS-2 InSAR","authors":"Jeng-Hann Chong, Bar Oryan, Lin Shen, Michael S. Steckler, Eric O. Lindsey","doi":"10.1029/2024jb030003","DOIUrl":"https://doi.org/10.1029/2024jb030003","url":null,"abstract":"The shallow portion of a megathrust represents the zone of first contact between two colliding plates, and its rheological properties control the seismic and tsunami hazards generated by the fault. The high cost of underwater geodetic data collection results in sparse observations, leading to limited constraints on the interseismic behavior of megathrusts. The Rakhine-Bangladesh megathrust offers a unique opportunity to probe the behavior of the shallow megathrust as it is the only ocean-continent subduction zone where the near-trench region is fully accessible on land. Here, we use observations from ALOS-2 wide-swath imagery spanning 2015 to 2022 to conduct an InSAR timeseries analysis of the overriding plate within Bangladesh and the Indo-Myanmar Ranges. We identify a narrow pattern of alternating uplift and subsidence associated with mapped anticlines but show that it cannot be explained by slip on the megathrust or other fault structures. Instead, we argue that the deformation is likely caused by active aseismic folding within the wedge above a shallow decollement. We show that estimates of the decollement depth derived from a viscous folding model and the observed anticline spacing are in agreement with previous seismic observations of the decollement depth across the fold belt. We suggest that the role of ductile deformation in the overriding plate in subduction zones may be more important than previously recognized.","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"20 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-12-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142902235","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Constraints on the Seismogenic Stress Tensor in Northeastern South Island, New Zealand","authors":"Olivia Leigh Walbert, Eric Andreas Hetland","doi":"10.1029/2024jb028877","DOIUrl":"https://doi.org/10.1029/2024jb028877","url":null,"abstract":"The seismogenic tensorial stresses in the crust beneath northeastern South Island, New Zealand that are responsible for the 2010 <span data-altimg=\"/cms/asset/b1a4cc5b-462a-4703-8b84-bce8b7bcd620/jgrb57069-math-0001.png\"></span><mjx-container ctxtmenu_counter=\"243\" ctxtmenu_oldtabindex=\"1\" jax=\"CHTML\" role=\"application\" sre-explorer- style=\"font-size: 103%; position: relative;\" tabindex=\"0\"><mjx-math aria-hidden=\"true\" location=\"graphic/jgrb57069-math-0001.png\"><mjx-semantics><mjx-mrow data-semantic-annotation=\"clearspeak:unit\" data-semantic-children=\"2,3\" data-semantic-content=\"4\" data-semantic- data-semantic-role=\"implicit\" data-semantic-speech=\"upper M Subscript w Baseline 7.2\" data-semantic-type=\"infixop\"><mjx-msub data-semantic-children=\"0,1\" data-semantic- data-semantic-parent=\"5\" data-semantic-role=\"latinletter\" data-semantic-type=\"subscript\"><mjx-mi data-semantic-annotation=\"clearspeak:simple\" data-semantic-font=\"italic\" data-semantic- data-semantic-parent=\"2\" data-semantic-role=\"latinletter\" data-semantic-type=\"identifier\"><mjx-c></mjx-c></mjx-mi><mjx-script style=\"vertical-align: -0.15em; margin-left: -0.081em;\"><mjx-mi data-semantic-annotation=\"clearspeak:simple\" data-semantic-font=\"italic\" data-semantic- data-semantic-parent=\"2\" data-semantic-role=\"latinletter\" data-semantic-type=\"identifier\" size=\"s\"><mjx-c></mjx-c></mjx-mi></mjx-script></mjx-msub><mjx-mo data-semantic-added=\"true\" data-semantic- data-semantic-operator=\"infixop,⁢\" data-semantic-parent=\"5\" data-semantic-role=\"multiplication\" data-semantic-type=\"operator\" style=\"margin-left: 0.056em; margin-right: 0.056em;\"><mjx-c></mjx-c></mjx-mo><mjx-mn data-semantic-annotation=\"clearspeak:simple\" data-semantic-font=\"normal\" data-semantic- data-semantic-parent=\"5\" data-semantic-role=\"float\" data-semantic-type=\"number\"><mjx-c></mjx-c><mjx-c></mjx-c><mjx-c></mjx-c></mjx-mn></mjx-mrow></mjx-semantics></mjx-math><mjx-assistive-mml display=\"inline\" unselectable=\"on\"><math altimg=\"urn:x-wiley:21699313:media:jgrb57069:jgrb57069-math-0001\" display=\"inline\" location=\"graphic/jgrb57069-math-0001.png\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><semantics><mrow data-semantic-=\"\" data-semantic-annotation=\"clearspeak:unit\" data-semantic-children=\"2,3\" data-semantic-content=\"4\" data-semantic-role=\"implicit\" data-semantic-speech=\"upper M Subscript w Baseline 7.2\" data-semantic-type=\"infixop\"><msub data-semantic-=\"\" data-semantic-children=\"0,1\" data-semantic-parent=\"5\" data-semantic-role=\"latinletter\" data-semantic-type=\"subscript\"><mi data-semantic-=\"\" data-semantic-annotation=\"clearspeak:simple\" data-semantic-font=\"italic\" data-semantic-parent=\"2\" data-semantic-role=\"latinletter\" data-semantic-type=\"identifier\">M</mi><mi data-semantic-=\"\" data-semantic-annotation=\"clearspeak:simple\" data-semantic-font=\"italic\" data-semantic-parent=\"2\" data-semantic-role=\"latinletter\" data-semantic-type=\"identifier\">w</mi></msub><mo data-semantic-=\"\" data-semantic-added=\"true\" data-semantic-operator=\"infixop,⁢\" data","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"3 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-12-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142902237","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Extracting Site Effects From P-wave spectra: Application of Cluster-Event Method 2 (CEM2) in the Tohoku Region, Japan","authors":"Pei-Ru Jian, Ban-Yuan Kuo","doi":"10.1029/2024jb028955","DOIUrl":"https://doi.org/10.1029/2024jb028955","url":null,"abstract":"Theories related to the Earth's attenuation effect and earthquake source properties predict a similar spectral falloff of body waves, creating severe trade-off problems when determining these two processes from waveform spectra. Previous efforts attempted to suppress this trade-off by either applying an empirical Green's function or conducting linear inversion with a specially designed event–station configuration. However, both approaches encounter difficulties when dealing with large datasets or site effect contamination. In this study, we modify a previously used cluster-event method (CEM), combining both the spectral amplitude and the spectral ratio of the P-waves for the clustering of events (CEM2); we then apply CEM2 to the High-Sensitivity Seismograph Network data in the Tohoku region of Japan. An initial inversion with CEM2 yields the first estimates of the source and path parameters, that is, the corner frequency (<i>f</i>_<i>c</i>) and the quality factor (<i>Q</i>). The residuals of this inversion demonstrate distinct spectral characteristics that are well correlated with vertical-to-horizontal (V/H) spectral ratios of the P-coda waves at each station, suggesting that they represent a form of site response unaccounted for by theoretical predictions of <i>Q</i> and <i>f</i>_<i>c</i>. After removing this particular site response, the second inversion yields an improved determination of <i>Q</i>. We hypothesize that this site effect is dominated by P to SV conversion upon P-wave arrival and develops and amplifies toward the coda waves. Furthermore, the site effect demonstrates systematic regional characteristics, some of which correlate well with those derived from the V/H spectral ratios of the P-coda waves.","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"2 2 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142888441","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Stabilized Unfitted Finite Element Method for Poroelasticity With Weak Discontinuity","authors":"Zhijun Liu, Yuxin Tong, Yimin Zhang, Hong Zheng, Fanyu Zhang","doi":"10.1029/2024jb030155","DOIUrl":"https://doi.org/10.1029/2024jb030155","url":null,"abstract":"Poromechanics problems in geotechnical and geological contexts often involve complex formations with numerous boundaries and material interfaces, which significantly complicate numerical analysis and simulation. The traditional finite element method (FEM) encounters substantial challenges in these scenarios because it requires the mesh to conform precisely to each boundary and interface. This requirement complicates preprocessing and necessitates meticulous manual control to achieve a high-quality mesh. In contrast, unfitted FEMs are well-suited for these problems as they do not require the mesh to align with the model geometry. We propose a stabilized unfitted FEM that incorporates Nitsche's method and ghost penalty stabilization techniques to address complex poroelasticity problems. This approach treats material interfaces as weak discontinuities and ensures that compatibility conditions are satisfied. The proposed method allows the mesh to be independent of both boundaries and material interfaces. Nitsche's method is used to weakly enforce both Dirichlet boundary conditions and interface compatibility conditions, resulting in a symmetric weak form. Additionally, three types of ghost penalty terms are introduced for elements intersected by boundaries or interfaces, effectively eliminating cut-induced ill-conditioning. The proposed methodology has been validated through benchmark and practical problems, demonstrating optimal convergence and exceptional stability. This approach significantly enhances the stability and efficiency of hydro-mechanical analyses for complex geotechnical and geological problems.","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"41 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-12-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142888446","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Beyond the Average: Computation of Vertical Profiles in Dilute Pyroclastic Density Currents and Their Use in Shallow-Water Models","authors":"B. Keim, M. de’ Michieli Vitturi","doi":"10.1029/2024jb029975","DOIUrl":"https://doi.org/10.1029/2024jb029975","url":null,"abstract":"Pyroclastic density currents (PDCs) present significant hazards due to their high temperatures and dynamic pressures. Accurate estimation of dynamic pressure, vital for assessing potential damage, requires knowledge of the vertical variations of velocity and particle concentration within the PDC, particularly in the first few meters of the flow above the ground. Existing approaches to dynamic pressure calculations used in hazard assessment are often based on average values for velocity and particle volume fraction. These average values may misrepresent the flow dynamics, especially near the base of the flow where the gradients of flow variables are larger. Here, we present a new, physically based approach that allows for the calculation of the vertical profiles of velocity and concentration from a combination of depth-averaged values for these properties and non-dimensional flow parameters. Finally, we demonstrate the use of these profiles within an existing shallow-water model and show its potential applications toward probabilistic hazard assessment.","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"31 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142887175","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}