Pub Date : 2025-12-06DOI: 10.1016/j.tecto.2025.231036
Yi-Chu Hua , Kate Huihsuan Chen , Satoshi Ide , Pei-Ying Patty Lin
We analyze ∼7000 tectonic tremors recorded between 2012 and 2022 across five clusters along Taiwan's mountain belt at depths of 30–50 km, providing new insights into slow fault slip within an active continental collision zone. All clusters occur above the Moho, exhibit thrust-dominant focal mechanisms, and are distinct from crustal seismicity. Tidal sensitivity varies spatially, with Clusters 2–5, located in zones of active collision and subduction termination, showing strong modulation (α = 0.53–0.75), while Cluster 1, situated in a post-collisional extensional environment near the Okinawa Trough, exhibits weaker sensitivity (α ≈ 0.3). These variations correlate with differences in tidal stress amplitude and tectonic regime. Moment tensor inversions reveal consistent thrusting styles, but principal stress orientations vary with depth, with σ₁ rotating from vertical in the upper crust to horizontal at tremor depths. This supports a two-layer deformation model shaped by orogenic collapse and lower crustal convergence-parallel shear. Our findings demonstrate that tremor generation in Taiwan reflects evolving stress regimes, fluid-assisted weakening, and structural heterogeneity associated with the interplay of collision, subduction, and back-arc extension. Tremors thus serve as sensitive indicators of deep-seated tectonic processes in dynamically evolving mountain belts.
{"title":"Characteristics and generation mechanisms of tremors across a mountain belt","authors":"Yi-Chu Hua , Kate Huihsuan Chen , Satoshi Ide , Pei-Ying Patty Lin","doi":"10.1016/j.tecto.2025.231036","DOIUrl":"10.1016/j.tecto.2025.231036","url":null,"abstract":"<div><div>We analyze ∼7000 tectonic tremors recorded between 2012 and 2022 across five clusters along Taiwan's mountain belt at depths of 30–50 km, providing new insights into slow fault slip within an active continental collision zone. All clusters occur above the Moho, exhibit thrust-dominant focal mechanisms, and are distinct from crustal seismicity. Tidal sensitivity varies spatially, with Clusters 2–5, located in zones of active collision and subduction termination, showing strong modulation (α = 0.53–0.75), while Cluster 1, situated in a post-collisional extensional environment near the Okinawa Trough, exhibits weaker sensitivity (α ≈ 0.3). These variations correlate with differences in tidal stress amplitude and tectonic regime. Moment tensor inversions reveal consistent thrusting styles, but principal stress orientations vary with depth, with σ₁ rotating from vertical in the upper crust to horizontal at tremor depths. This supports a two-layer deformation model shaped by orogenic collapse and lower crustal convergence-parallel shear. Our findings demonstrate that tremor generation in Taiwan reflects evolving stress regimes, fluid-assisted weakening, and structural heterogeneity associated with the interplay of collision, subduction, and back-arc extension. Tremors thus serve as sensitive indicators of deep-seated tectonic processes in dynamically evolving mountain belts.</div></div>","PeriodicalId":22257,"journal":{"name":"Tectonophysics","volume":"920 ","pages":"Article 231036"},"PeriodicalIF":2.6,"publicationDate":"2025-12-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145689915","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-05DOI: 10.1016/j.tecto.2025.231035
Xu Han, Jin-Gen Dai, Bo-Rong Liu, Zhi-Cheng Yu
The Himalayan orogen is an ideal natural laboratory for investigating exhumation processes due to the diverse and distinctive tectonic and climatic features. Whereas numerous low-temperature thermochronometric studies have been conducted on southern flank of the orogen (mainly in the Greater Himalaya and Lesser Himalaya), the dominant controls on exhumation remain debated due to the complex interactions between climate, topography, and tectonics. In contrast, the Tethyan Himalaya along the northern flank exhibits relatively limited recent tectonic activity and spatially uniform precipitation, which makes it more suitable for exploring controlling factors of exhumation. To reconstruct the exhumation history of the eastern Tethyan Himalaya and identify its controls, we collected bedrock samples along river channels for apatite (UTh)/He dating. Low-temperature thermochronology and thermal history modeling indicate three rapid exhumation phases: ca. 10–7 Ma, ca. 6–3 Ma, and ca. 2–0 Ma. The ca. 10–7 Ma phase correlates with the Asian summer monsoon intensification, during which increased precipitation enhanced fluvial incision. The ca. 6–3 Ma phase is the last vestige of tectonically controlled rapid exhumation in Himalaya, subsequent to the decline of the India-Asia convergence rate at ca. 6 Ma. The most recent phase (<2 Ma) is primarily linked to localized normal faulting. Additionally, a pronounced geomorphic contrast is observed: river valleys south of the Himalayan drainage divide exhibit significantly wider widths compared to tributaries of the upper and lower Yarlung River located north of the divide. These differences correlate with exhumation timing, as areas experiencing older exhumation phases exhibit wider valleys. This correlation suggests that fluvial erosion exerts a long-term control on exhumation patterns within the orogen.
{"title":"Exhumation history of the eastern Tethyan Himalaya: Evidence from Apatite (UTh)/He Thermochronology","authors":"Xu Han, Jin-Gen Dai, Bo-Rong Liu, Zhi-Cheng Yu","doi":"10.1016/j.tecto.2025.231035","DOIUrl":"10.1016/j.tecto.2025.231035","url":null,"abstract":"<div><div>The Himalayan orogen is an ideal natural laboratory for investigating exhumation processes due to the diverse and distinctive tectonic and climatic features. Whereas numerous low-temperature thermochronometric studies have been conducted on southern flank of the orogen (mainly in the Greater Himalaya and Lesser Himalaya), the dominant controls on exhumation remain debated due to the complex interactions between climate, topography, and tectonics. In contrast, the Tethyan Himalaya along the northern flank exhibits relatively limited recent tectonic activity and spatially uniform precipitation, which makes it more suitable for exploring controlling factors of exhumation. To reconstruct the exhumation history of the eastern Tethyan Himalaya and identify its controls, we collected bedrock samples along river channels for apatite (U<img>Th)/He dating. Low-temperature thermochronology and thermal history modeling indicate three rapid exhumation phases: ca. 10–7 Ma, ca. 6–3 Ma, and ca. 2–0 Ma. The ca. 10–7 Ma phase correlates with the Asian summer monsoon intensification, during which increased precipitation enhanced fluvial incision. The ca. 6–3 Ma phase is the last vestige of tectonically controlled rapid exhumation in Himalaya, subsequent to the decline of the India-Asia convergence rate at ca. 6 Ma. The most recent phase (<2 Ma) is primarily linked to localized normal faulting. Additionally, a pronounced geomorphic contrast is observed: river valleys south of the Himalayan drainage divide exhibit significantly wider widths compared to tributaries of the upper and lower Yarlung River located north of the divide. These differences correlate with exhumation timing, as areas experiencing older exhumation phases exhibit wider valleys. This correlation suggests that fluvial erosion exerts a long-term control on exhumation patterns within the orogen.</div></div>","PeriodicalId":22257,"journal":{"name":"Tectonophysics","volume":"920 ","pages":"Article 231035"},"PeriodicalIF":2.6,"publicationDate":"2025-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145689914","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-05DOI: 10.1016/j.tecto.2025.231030
Jamison Assunção , Boris J.P. Kaus , Andrea Piccolo , Nicolas Riel , Victor Sacek
Plate velocities on Earth are all on the order of several centimeters per year, despite large uncertainties in mantle rheology and plate geometry. Here, we conducted a series of 2D self-sustained Andean-type subduction simulations, and investigated how the convergence speed between an oceanic and a continental lithosphere is influenced by plate geometry, lower mantle rheology and the presence of a partial melt zone (PMZ) of relatively low viscosity under the oceanic lithosphere. We ran sets of simulations with different oceanic plate lengths at the surface (OPLS), ranging from 1000 to 5000 km. The overall subduction pattern displayed a relatively rapid acceleration of the subducting plate, followed by a deceleration of approximately the same duration until the plate reached the lower mantle. After this point, the convergence velocity tends to remain stable, varying up to 3.5 cm/yr during subduction across most of the simulated scenarios, supporting the hypothesis of sustained convergence rates for tens of millions of years. We found a linear relationship between the OPLS and the average convergence speed after the plates reach the 660-km discontinuity, with the average convergence velocity decreasing by a rate of approximately 1.3 cm/yr per each additional 1000 km of OPLS. We also tested the sensitivity of the average convergence velocity to variations in lower mantle viscosity and found that decreasing the viscosity from 1.5 × 1022 to 0.5 × 1022 Pa s increased the convergence speed of the subducting plate – after reaching the 660-km discontinuity – by up to a factor of three, hindering convergence stability. By testing the effect of a PMZ modeled via asthenospheric rheology scaling, we found that it does not significantly alter the convergence speed stability or affect the kinematics. Instead, it primarily mimics the behavior of a scenario with a smaller oceanic plate.
地球上的板块速度都在每年几厘米左右，尽管地幔流变学和板块几何结构存在很大的不确定性。在此，我们进行了一系列二维自持续安第斯型俯冲模拟，并研究了板块几何形状、下地幔流变学以及海洋岩石圈下相对低粘度的部分熔融带（PMZ）的存在如何影响海洋和大陆岩石圈之间的收敛速度。我们用不同的海洋表面板块长度（ops）进行了一组模拟，范围从1000到5000公里。整个俯冲模式表现为俯冲板块的相对快速加速，随后是一个大约相同时间的减速，直到板块到达下地幔。在此之后，收敛速度趋于稳定，在大多数模拟情景中，在俯冲期间变化高达3.5 cm/年，支持持续数千万年的收敛速度假设。在到达660 km不连续面后，ops与平均辐合速度呈线性关系，每增加1000 km ops，平均辐合速度降低约1.3 cm/yr。我们还测试了平均辐合速度对下地幔黏度变化的敏感性，发现黏度从1.5 × 1022 Pa s降低到0.5 × 1022 Pa s会使俯冲板块的辐合速度（在达到660公里的不连续面后）增加三倍，从而阻碍了辐合的稳定性。通过测试软流圈流变缩放模型对PMZ的影响，我们发现它不会显著改变收敛速度、稳定性或影响运动学。相反，它主要是模仿一个较小的海洋板块的行为。
{"title":"Sensitivity analysis of lithospheric convergence velocity in numerical simulations of self-sustained Andean-type subduction","authors":"Jamison Assunção , Boris J.P. Kaus , Andrea Piccolo , Nicolas Riel , Victor Sacek","doi":"10.1016/j.tecto.2025.231030","DOIUrl":"10.1016/j.tecto.2025.231030","url":null,"abstract":"<div><div>Plate velocities on Earth are all on the order of several centimeters per year, despite large uncertainties in mantle rheology and plate geometry. Here, we conducted a series of 2D self-sustained Andean-type subduction simulations, and investigated how the convergence speed between an oceanic and a continental lithosphere is influenced by plate geometry, lower mantle rheology and the presence of a partial melt zone (PMZ) of relatively low viscosity under the oceanic lithosphere. We ran sets of simulations with different oceanic plate lengths at the surface (OPLS), ranging from 1000 to 5000 km. The overall subduction pattern displayed a relatively rapid acceleration of the subducting plate, followed by a deceleration of approximately the same duration until the plate reached the lower mantle. After this point, the convergence velocity tends to remain stable, varying up to 3.5 cm/yr during subduction across most of the simulated scenarios, supporting the hypothesis of sustained convergence rates for tens of millions of years. We found a linear relationship between the OPLS and the average convergence speed after the plates reach the 660-km discontinuity, with the average convergence velocity decreasing by a rate of approximately 1.3 cm/yr per each additional 1000 km of OPLS. We also tested the sensitivity of the average convergence velocity to variations in lower mantle viscosity and found that decreasing the viscosity from 1.5 × 10<sup>22</sup> to 0.5 × 10<sup>22</sup> Pa s increased the convergence speed of the subducting plate – after reaching the 660-km discontinuity – by up to a factor of three, hindering convergence stability. By testing the effect of a PMZ modeled via asthenospheric rheology scaling, we found that it does not significantly alter the convergence speed stability or affect the kinematics. Instead, it primarily mimics the behavior of a scenario with a smaller oceanic plate.</div></div>","PeriodicalId":22257,"journal":{"name":"Tectonophysics","volume":"920 ","pages":"Article 231030"},"PeriodicalIF":2.6,"publicationDate":"2025-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145689916","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-02DOI: 10.1016/j.tecto.2025.231033
Anhua Ju , Haiqing Yang , Xingyue Li , Lixin Peng
The dynamic processes of the Earth's surface before and after an earthquake have long been central to seismological research. However, the relationship between surface motions and seismic activity remains difficult to establish. This study proposes a novel method for quantifying the orderliness of surface motions. The method defines trend direction at each time step based on the three-dimensional displacement time series derived from Sentinel-1 SAR images from different orbits. It also describes the aggregation and diffusion effects of motion directions before and after the earthquake. Additionally, a horizontal displacement acceleration-deceleration detection model based on piecewise linear fitting identifies monthly acceleration and deceleration points throughout the seismic event. The results showed that the observable horizontal displacement was significantly larger than the vertical displacement, exhibiting the strike-slip faulting characteristics of the 2022 Mw 6.6 Menyuan earthquake. The average information entropy was 6.088 before the earthquake, dropped to 5.943 near the event, and rose to 6.067 afterward. Surface motion direction and amplitude exhibit a process of aggregation and acceleration followed by diffusion and deceleration. This indicates that geodetic techniques can detect subtle surface motion changes potentially linked to seismic preparation processes.
{"title":"The aggregation-diffusion effect of shallow motions in the 2022 Menyuan Mw 6.6 earthquake","authors":"Anhua Ju , Haiqing Yang , Xingyue Li , Lixin Peng","doi":"10.1016/j.tecto.2025.231033","DOIUrl":"10.1016/j.tecto.2025.231033","url":null,"abstract":"<div><div>The dynamic processes of the Earth's surface before and after an earthquake have long been central to seismological research. However, the relationship between surface motions and seismic activity remains difficult to establish. This study proposes a novel method for quantifying the orderliness of surface motions. The method defines trend direction at each time step based on the three-dimensional displacement time series derived from Sentinel-1 SAR images from different orbits. It also describes the aggregation and diffusion effects of motion directions before and after the earthquake. Additionally, a horizontal displacement acceleration-deceleration detection model based on piecewise linear fitting identifies monthly acceleration and deceleration points throughout the seismic event. The results showed that the observable horizontal displacement was significantly larger than the vertical displacement, exhibiting the strike-slip faulting characteristics of the 2022 Mw 6.6 Menyuan earthquake. The average information entropy was 6.088 before the earthquake, dropped to 5.943 near the event, and rose to 6.067 afterward. Surface motion direction and amplitude exhibit a process of aggregation and acceleration followed by diffusion and deceleration. This indicates that geodetic techniques can detect subtle surface motion changes potentially linked to seismic preparation processes.</div></div>","PeriodicalId":22257,"journal":{"name":"Tectonophysics","volume":"920 ","pages":"Article 231033"},"PeriodicalIF":2.6,"publicationDate":"2025-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145658139","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-01DOI: 10.1016/j.tecto.2025.231032
Menglong Liao , Yuanzhi Cheng , Bo Han , Zhonghe Pang
The Daggyai geothermal field in the southern Tibetan Plateau is characterized by abundant boiling springs and geysers, with thermal waters exhibiting significant enrichment in trace elements (As, B, and Li). To investigate the formation mechanisms and geothermal potential of this hydrothermal system, we conducted a magnetotelluric (MT) survey along a north–south profile across the field and developed a 3D resistivity model using ModEM. Integration of resistivity modeling, geochemical data, and geological observations reveals the following characteristics: (1) A shallow low-resistivity body functioning as the primary geothermal reservoir; (2) A low-resistivity body at intermediate depths (4–10 km) indicating either a fluid-dominated high-temperature rock mass or a zone containing a high aqueous phase with limited partial melt; (3) A pronounced low-resistivity body at depths of 10–18 km representing the principal heat source, interpreted as a partially molten rock body with melt fractions of 5.72–11.15%; (4) An additional deep low-resistivity body providing evidence of significant crustal melting, with estimated melt fractions of 8.13–14.61%. The resistivity structure demonstrates clear electrical connectivity between the deep crustal melting zone and the principal heat source region. We propose that the ongoing India–Eurasia continental collision facilitates the upward migration of crustal melts, which subsequently accumulate beneath the Daggyai field, sustaining its high-temperature hydrothermal system. This mechanism suggests that other high-temperature geothermal systems in southern Tibet characterized by shallow partial melt heat sources may share similar patterns of melt migration and accumulation, providing crucial insights into the evolution of geothermal systems across the southern Tibetan Plateau.
{"title":"Control of crustal melt migration on geothermal system development in the Daggyai area, southern Tibet: Insights from 3D magnetotelluric imaging","authors":"Menglong Liao , Yuanzhi Cheng , Bo Han , Zhonghe Pang","doi":"10.1016/j.tecto.2025.231032","DOIUrl":"10.1016/j.tecto.2025.231032","url":null,"abstract":"<div><div>The Daggyai geothermal field in the southern Tibetan Plateau is characterized by abundant boiling springs and geysers, with thermal waters exhibiting significant enrichment in trace elements (As, B, and Li). To investigate the formation mechanisms and geothermal potential of this hydrothermal system, we conducted a magnetotelluric (MT) survey along a north–south profile across the field and developed a 3D resistivity model using ModEM. Integration of resistivity modeling, geochemical data, and geological observations reveals the following characteristics: (1) A shallow low-resistivity body functioning as the primary geothermal reservoir; (2) A low-resistivity body at intermediate depths (4–10 km) indicating either a fluid-dominated high-temperature rock mass or a zone containing a high aqueous phase with limited partial melt; (3) A pronounced low-resistivity body at depths of 10–18 km representing the principal heat source, interpreted as a partially molten rock body with melt fractions of 5.72–11.15%; (4) An additional deep low-resistivity body providing evidence of significant crustal melting, with estimated melt fractions of 8.13–14.61%. The resistivity structure demonstrates clear electrical connectivity between the deep crustal melting zone and the principal heat source region. We propose that the ongoing India–Eurasia continental collision facilitates the upward migration of crustal melts, which subsequently accumulate beneath the Daggyai field, sustaining its high-temperature hydrothermal system. This mechanism suggests that other high-temperature geothermal systems in southern Tibet characterized by shallow partial melt heat sources may share similar patterns of melt migration and accumulation, providing crucial insights into the evolution of geothermal systems across the southern Tibetan Plateau.</div></div>","PeriodicalId":22257,"journal":{"name":"Tectonophysics","volume":"919 ","pages":"Article 231032"},"PeriodicalIF":2.6,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145658140","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-30DOI: 10.1016/j.tecto.2025.231031
Wen Meng , Yonghua Li , Xiaoyu Yang
We investigate a contrast in the anisotropic complexity beneath different blocks of the North China Craton (NCC) using shear wave splitting measurements from teleseismic SKS, SKKS, and PKS phases recorded at 113 permanent stations over fifteen years. The systematic variations of splitting parameters with back azimuth observed at stations across various blocks have been modeled using two-layers anisotropic structure. The observed ENE-WSW-oriented fast polarization direction (FPD) in the upper layer beneath the Ordos Block is interpreted as frozen-in lithospheric anisotropy, likely inherited during cratonic formation. The FPD of the upper layer across the Circum-Ordos Rifts is consistent with the rift strike, which may be the result of a combined effect of pre-rift orogenic-related lithospheric fabric, oriented melt pockets or/and simple shear deformation associated with the counterclockwise rotation of the Ordos Block. The FPD in the upper layer beneath the Taihang Orogenic Belt is consistent with the strike of the orogenic belt, suggesting a possible association with past lithospheric orogenic deformation. In the lower layers of all regions modeled with two-layers anisotropic structure, FPDs are consistent with the direction of absolute plate motion (APM), reflecting the flow in the asthenosphere. However, in regions where the lithospheric thickness changes rapidly, such as along the margins of the Ordos Block and around the Datong Volcanic area, there are significant directional deviations between FPDs and APM. This suggests that lithospheric heterogeneity and upwelling mantle flow have a significant modulating effect on the asthenospheric flow.
{"title":"Complex seismic anisotropy beneath the North China Craton from long-term shear wave splitting analysis","authors":"Wen Meng , Yonghua Li , Xiaoyu Yang","doi":"10.1016/j.tecto.2025.231031","DOIUrl":"10.1016/j.tecto.2025.231031","url":null,"abstract":"<div><div>We investigate a contrast in the anisotropic complexity beneath different blocks of the North China Craton (NCC) using shear wave splitting measurements from teleseismic SKS, SKKS, and PKS phases recorded at 113 permanent stations over fifteen years. The systematic variations of splitting parameters with back azimuth observed at stations across various blocks have been modeled using two-layers anisotropic structure. The observed ENE-WSW-oriented fast polarization direction (FPD) in the upper layer beneath the Ordos Block is interpreted as frozen-in lithospheric anisotropy, likely inherited during cratonic formation. The FPD of the upper layer across the Circum-Ordos Rifts is consistent with the rift strike, which may be the result of a combined effect of pre-rift orogenic-related lithospheric fabric, oriented melt pockets or/and simple shear deformation associated with the counterclockwise rotation of the Ordos Block. The FPD in the upper layer beneath the Taihang Orogenic Belt is consistent with the strike of the orogenic belt, suggesting a possible association with past lithospheric orogenic deformation. In the lower layers of all regions modeled with two-layers anisotropic structure, FPDs are consistent with the direction of absolute plate motion (APM), reflecting the flow in the asthenosphere. However, in regions where the lithospheric thickness changes rapidly, such as along the margins of the Ordos Block and around the Datong Volcanic area, there are significant directional deviations between FPDs and APM. This suggests that lithospheric heterogeneity and upwelling mantle flow have a significant modulating effect on the asthenospheric flow.</div></div>","PeriodicalId":22257,"journal":{"name":"Tectonophysics","volume":"920 ","pages":"Article 231031"},"PeriodicalIF":2.6,"publicationDate":"2025-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145650854","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-28DOI: 10.1016/j.tecto.2025.231029
Donna L. Whitney , Maximiliano Bezada , Lars N. Hansen , Christian Teyssier , Ikuko Wada , Xin Zhou
Tectonic escape is the movement of large, strike-slip fault-bounded blocks of lithosphere obliquely away from collision zones. The process of escape has occurred in its current form since the inception of plate tectonics and likely operated as ‘soft escape’ in the hotter, early Earth.
Escape is driven by collision of a smaller, stronger continent or terrane with a larger, weaker continent. The collider acts as an indenter following consumption of oceanic lithosphere at its leading edge, when collision commences between the indenter and the larger, overriding plate. Owing to heterogeneities in the strength of the escape system and the dynamics of neighboring regions, escape occurs in a preferred direction: escaping lithosphere moves as a wedge-shaped block away from rheologically strong domains and towards weaker, thinner, and/or extending domains.
Insights from active escape systems and thermo-mechanical models indicate that pre- to syn-collision factors that drive or facilitate escape likely include (1) the presence or development of localized weak zones in the overriding plate and along the indenter-ocean boundary, and (2) the continuation of a driving force for escape following slab break-off downdip of the indenter. In large-scale active escape systems, the bounding strike-slip fault closest to the collisional plate boundary is more seismically active than the escape fault further from the collision zone.
Escape has been a significant contributor to heat and mass transfer over geological time, and it affects the lithosphere from mantle to surface. It is a mechanism for the formation of new plates from existing ones and has had a major role in the tectonic history of the planet; e.g., during supercontinent assembly and dispersal. Although escape involves profound strain localization along the bounding seismically-active strike-slip faults, the effects of the escape system encompass processes within and beyond the escaping block or plate.
{"title":"Escape tectonics","authors":"Donna L. Whitney , Maximiliano Bezada , Lars N. Hansen , Christian Teyssier , Ikuko Wada , Xin Zhou","doi":"10.1016/j.tecto.2025.231029","DOIUrl":"10.1016/j.tecto.2025.231029","url":null,"abstract":"<div><div>Tectonic escape is the movement of large, strike-slip fault-bounded blocks of lithosphere obliquely away from collision zones. The process of escape has occurred in its current form since the inception of plate tectonics and likely operated as ‘soft escape’ in the hotter, early Earth.</div><div>Escape is driven by collision of a smaller, stronger continent or terrane with a larger, weaker continent. The collider acts as an indenter following consumption of oceanic lithosphere at its leading edge, when collision commences between the indenter and the larger, overriding plate. Owing to heterogeneities in the strength of the escape system and the dynamics of neighboring regions, escape occurs in a preferred direction: escaping lithosphere moves as a wedge-shaped block away from rheologically strong domains and towards weaker, thinner, and/or extending domains.</div><div>Insights from active escape systems and thermo-mechanical models indicate that pre- to syn-collision factors that drive or facilitate escape likely include (1) the presence or development of localized weak zones in the overriding plate and along the indenter-ocean boundary, and (2) the continuation of a driving force for escape following slab break-off downdip of the indenter. In large-scale active escape systems, the bounding strike-slip fault closest to the collisional plate boundary is more seismically active than the escape fault further from the collision zone.</div><div>Escape has been a significant contributor to heat and mass transfer over geological time, and it affects the lithosphere from mantle to surface. It is a mechanism for the formation of new plates from existing ones and has had a major role in the tectonic history of the planet; e.g., during supercontinent assembly and dispersal. Although escape involves profound strain localization along the bounding seismically-active strike-slip faults, the effects of the escape system encompass processes within and beyond the escaping block or plate.</div></div>","PeriodicalId":22257,"journal":{"name":"Tectonophysics","volume":"920 ","pages":"Article 231029"},"PeriodicalIF":2.6,"publicationDate":"2025-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145613838","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-27DOI: 10.1016/j.tecto.2025.231008
A. Septier , J. Déverchère , J. Perrot , A. Renouard
Understanding earthquake depth distribution is critical for improving seismogenesis models. While the spatiotemporal pattern of earthquakes is well studied, transient changes in depth distribution remain poorly explored. In this study, we investigate how crustal rheological parameters influence the depth of earthquakes through time, focusing on the Corinth rift, a well-monitored region experiencing a high-level seismic activity in a homogeneous extensional stress field.
To calculate crustal yield strength profiles, we compile geophysical and geological data, including heat flow, rock compositions and properties, Moho depth and strain rate. These estimates are then compared to a high-quality 11-year seismic catalogue of the region. An inversion approach is applied to identify crustal layers associated with persistent versus sporadic seismicity defined here instead of the conventional background versus clustered seismicity.
Our time analysis reveals that the persistent seismicity nicely matches the theoretical brittle–ductile transition and allows us to confidently define the seismogenic thickness, while sporadic seismicity is clustered at depths associated with swarm occurrences. Both distributions are subject to kilometre-scale changes after magnitude 4.0 – 5.5 earthquakes, evidencing a relaxation process even after moderate magnitude events. We conclude that in specific case studies aiming to compare depth distribution and yield strength in the crust, the application of declustering methods may not be optimal for examining the potential rheological controls on earthquake depth distribution and their temporal variations. Instead, the analysis of persistent and sporadic seismicity defined in this study is more accurate and reliable than a declustering approach and offers new and valuable insights for this comparison.
{"title":"Seismogenic and rheological behaviours from time-dependent analysis of earthquake depth distribution in the Corinth Rift","authors":"A. Septier , J. Déverchère , J. Perrot , A. Renouard","doi":"10.1016/j.tecto.2025.231008","DOIUrl":"10.1016/j.tecto.2025.231008","url":null,"abstract":"<div><div>Understanding earthquake depth distribution is critical for improving seismogenesis models. While the spatiotemporal pattern of earthquakes is well studied, transient changes in depth distribution remain poorly explored. In this study, we investigate how crustal rheological parameters influence the depth of earthquakes through time, focusing on the Corinth rift, a well-monitored region experiencing a high-level seismic activity in a homogeneous extensional stress field.</div><div>To calculate crustal yield strength profiles, we compile geophysical and geological data, including heat flow, rock compositions and properties, Moho depth and strain rate. These estimates are then compared to a high-quality 11-year seismic catalogue of the region. An inversion approach is applied to identify crustal layers associated with persistent versus sporadic seismicity defined here instead of the conventional background versus clustered seismicity.</div><div>Our time analysis reveals that the persistent seismicity nicely matches the theoretical brittle–ductile transition and allows us to confidently define the seismogenic thickness, while sporadic seismicity is clustered at depths associated with swarm occurrences. Both distributions are subject to kilometre-scale changes after magnitude 4.0 – 5.5 earthquakes, evidencing a relaxation process even after moderate magnitude events. We conclude that in specific case studies aiming to compare depth distribution and yield strength in the crust, the application of declustering methods may not be optimal for examining the potential rheological controls on earthquake depth distribution and their temporal variations. Instead, the analysis of persistent and sporadic seismicity defined in this study is more accurate and reliable than a declustering approach and offers new and valuable insights for this comparison.</div></div>","PeriodicalId":22257,"journal":{"name":"Tectonophysics","volume":"919 ","pages":"Article 231008"},"PeriodicalIF":2.6,"publicationDate":"2025-11-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145611972","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-27DOI: 10.1016/j.tecto.2025.231012
Viesturs Zandersons, Jānis Karušs
We present a detailed analysis of crustal thickness across the Baltic States using two geophysical methods: receiver function (RF) analysis and gravity inversion. We calculate P-wave RFs for sixteen broadband seismic stations and estimate Moho depths using both standard and sedimentary layer corrected H-k stacking. RF results show crustal thicknesses in the range from 35.5 km in northern Latvia to 55.7 km in southeastern Lithuania and northern Estonia, with corresponding ratios between 1.70 and 1.86. These results are broadly aligned with established Proterozoic tectonic domains and prior deep seismic sounding (DSS) profiles.
Gravity inversion is performed using a terrain-corrected and spectrally filtered Bouguer anomaly field derived from WGM2012, constrained by DSS and RF-derived Moho depths. A two-layer crust-mantle tesseroid model is optimised using cross-validation and grid search. The resulting gravity-derived Moho depth varies from 44 to 49 km, with a standard deviation of 4.39 km compared to seismic estimates. Major residuals of over 10 km are observed over the Kurzeme Batholith and the West Estonian domain, highlighting the limitations of the two-layer model in regions with complex crustal architecture.
We argue for a cautious interpretation of tectonic boundaries derived solely from potential field data. Our findings support the need for a new DSS transect and integrated gravity-seismic modelling to better constrain intra-crustal structure, especially in central Latvia, southern Lithuania and northwestern Estonia where current models show significant discrepancies.
{"title":"Receiver function and gravity inversion of the Moho depth beneath the Baltic states","authors":"Viesturs Zandersons, Jānis Karušs","doi":"10.1016/j.tecto.2025.231012","DOIUrl":"10.1016/j.tecto.2025.231012","url":null,"abstract":"<div><div>We present a detailed analysis of crustal thickness across the Baltic States using two geophysical methods: receiver function (RF) analysis and gravity inversion. We calculate P-wave RFs for sixteen broadband seismic stations and estimate Moho depths using both standard and sedimentary layer corrected H-k stacking. RF results show crustal thicknesses in the range from 35.5 km in northern Latvia to 55.7 km in southeastern Lithuania and northern Estonia, with corresponding <span><math><mrow><msub><mrow><mi>V</mi></mrow><mrow><mi>p</mi></mrow></msub><mo>/</mo><msub><mrow><mi>V</mi></mrow><mrow><mi>s</mi></mrow></msub></mrow></math></span> ratios between 1.70 and 1.86. These results are broadly aligned with established Proterozoic tectonic domains and prior deep seismic sounding (DSS) profiles.</div><div>Gravity inversion is performed using a terrain-corrected and spectrally filtered Bouguer anomaly field derived from WGM2012, constrained by DSS and RF-derived Moho depths. A two-layer crust-mantle tesseroid model is optimised using cross-validation and grid search. The resulting gravity-derived Moho depth varies from 44 to 49 km, with a standard deviation of 4.39 km compared to seismic estimates. Major residuals of over 10 km are observed over the Kurzeme Batholith and the West Estonian domain, highlighting the limitations of the two-layer model in regions with complex crustal architecture.</div><div>We argue for a cautious interpretation of tectonic boundaries derived solely from potential field data. Our findings support the need for a new DSS transect and integrated gravity-seismic modelling to better constrain intra-crustal structure, especially in central Latvia, southern Lithuania and northwestern Estonia where current models show significant discrepancies.</div></div>","PeriodicalId":22257,"journal":{"name":"Tectonophysics","volume":"919 ","pages":"Article 231012"},"PeriodicalIF":2.6,"publicationDate":"2025-11-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145611974","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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