In September 2022, eastern Taiwan was shaken by a series of earthquakes, known as the 2022 Taitung earthquakes. A total of 45 landslides were triggered by the earthquakes, and the frequency-area distribution revealed a scarcity of small- and large-scale landslides. Most of the landslides were moderate in scale, with areas ranging from 103 to 104 m2. We examined the relationship between the landslide distribution and earthquake source faults. The distances between landslides and active faults ranged from 0.82 to 17.65 km. The results allowed us to infer parameters of the source faults and the magnitudes of the earthquakes using a model proposed in a previous study, which aligns with the real situation. Furthermore, we analyzed the topographic and geological conditions associated with landslide distribution. We found that most landslides occurred on mid-hillsides or in close proximity to streams, in contrast to the findings of previous studies that highlighted ridge areas as the primary locations of coseismic landslides. As the source fault in this study is situated in a valley, with a flat plain on both sides, only six landslides occurred within 3 km of the fault. Seismic waves transmitted to distant mountains were attenuated and lacked the strength to have amplification on ridges. Because the seismic waves failed to reach higher mountains, the landslides predominantly occurred at lower elevations on steep slopes with more fragile geological conditions. Based on the comprehensive conditions of fault type and surrounding topography and geology, the landslides mostly occurred on mid-hillsides rather than on ridges.
{"title":"Spatial distribution of landslides triggered by the 2022 Taitung Earthquakes in relation to active fault systems, topographic effects, and geological conditions","authors":"Chi-Wen Chen , Lun-Wei Wei , Ryuji Yamada , Tomoyuki Iida","doi":"10.1016/j.geomorph.2025.109615","DOIUrl":"10.1016/j.geomorph.2025.109615","url":null,"abstract":"<div><div>In September 2022, eastern Taiwan was shaken by a series of earthquakes, known as the 2022 Taitung earthquakes. A total of 45 landslides were triggered by the earthquakes, and the frequency-area distribution revealed a scarcity of small- and large-scale landslides. Most of the landslides were moderate in scale, with areas ranging from 10<sup>3</sup> to 10<sup>4</sup> m<sup>2</sup>. We examined the relationship between the landslide distribution and earthquake source faults. The distances between landslides and active faults ranged from 0.82 to 17.65 km. The results allowed us to infer parameters of the source faults and the magnitudes of the earthquakes using a model proposed in a previous study, which aligns with the real situation. Furthermore, we analyzed the topographic and geological conditions associated with landslide distribution. We found that most landslides occurred on mid-hillsides or in close proximity to streams, in contrast to the findings of previous studies that highlighted ridge areas as the primary locations of coseismic landslides. As the source fault in this study is situated in a valley, with a flat plain on both sides, only six landslides occurred within 3 km of the fault. Seismic waves transmitted to distant mountains were attenuated and lacked the strength to have amplification on ridges. Because the seismic waves failed to reach higher mountains, the landslides predominantly occurred at lower elevations on steep slopes with more fragile geological conditions. Based on the comprehensive conditions of fault type and surrounding topography and geology, the landslides mostly occurred on mid-hillsides rather than on ridges.</div></div>","PeriodicalId":55115,"journal":{"name":"Geomorphology","volume":"473 ","pages":"Article 109615"},"PeriodicalIF":3.1,"publicationDate":"2025-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143137800","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}
Pub Date : 2025-01-20DOI: 10.1016/j.geomorph.2025.109616
Zeyu Chen, Hanzhi Zhang, Huayu Lu, Fan Lyu, Hengzhi Lyu, Ruixue Gao, Yang Chen, Mengying Wu
The Weihe River, originating from the northeastern Tibetan Plateau, is one of the most important tributaries of the Yellow River. The Cenozoic evolution of the Weihe River provides critical insights into the geomorphologic uplift of the northeastern Tibetan Plateau, and the drainage evolution of the Yellow River. However, the Paleogene evolution of the Weihe River remains poorly understood. The Weihe Basin, located adjacent to the northeast of the Tibetan Plateau and at the lower reaches of the Weihe River, preserved continuous sediments record spanning from the middle Eocene to the Oligocene. Source to sink analysis offers valuable evidence for deciphering regional drainage evolution. This study investigates the sediment provenance of the Eocene-Oligocene sedimentary strata in the Weihe Basin and its temporal variations, employing detrital zircon UPb dating on 19 new samples alongside sedimentary analyses. We find that the regional river drainage underwent two evolutionary of stages during this period. During the Eocene (ca. 46–34 Ma), the Weihe Basin was characterized by a shallow lacustrine environment, receiving clastic materials primarily from the surrounding areas. By the early Oligocene (ca. 34–31.7 Ma), contributions from the modern upper reaches of the Weihe River increased. This suggested that the proto-Weihe River system began to form during the Oligocene, exhibiting a pattern that closely resembles its modern configuration. This drainage evolution was mainly controlled by tectonic deformation of the northeastern Tibetan Plateau, and enhancement in headwards erosion due to increased precipitation.
{"title":"Evolution of the proto-Weihe River system during the Eocene–Oligocene: Evidence from sediment provenance of the Weihe Basin","authors":"Zeyu Chen, Hanzhi Zhang, Huayu Lu, Fan Lyu, Hengzhi Lyu, Ruixue Gao, Yang Chen, Mengying Wu","doi":"10.1016/j.geomorph.2025.109616","DOIUrl":"10.1016/j.geomorph.2025.109616","url":null,"abstract":"<div><div>The Weihe River, originating from the northeastern Tibetan Plateau, is one of the most important tributaries of the Yellow River. The Cenozoic evolution of the Weihe River provides critical insights into the geomorphologic uplift of the northeastern Tibetan Plateau, and the drainage evolution of the Yellow River. However, the Paleogene evolution of the Weihe River remains poorly understood. The Weihe Basin, located adjacent to the northeast of the Tibetan Plateau and at the lower reaches of the Weihe River, preserved continuous sediments record spanning from the middle Eocene to the Oligocene. Source to sink analysis offers valuable evidence for deciphering regional drainage evolution. This study investigates the sediment provenance of the Eocene-Oligocene sedimentary strata in the Weihe Basin and its temporal variations, employing detrital zircon U<img>Pb dating on 19 new samples alongside sedimentary analyses. We find that the regional river drainage underwent two evolutionary of stages during this period. During the Eocene (ca. 46–34 Ma), the Weihe Basin was characterized by a shallow lacustrine environment, receiving clastic materials primarily from the surrounding areas. By the early Oligocene (ca. 34–31.7 Ma), contributions from the modern upper reaches of the Weihe River increased. This suggested that the proto-Weihe River system began to form during the Oligocene, exhibiting a pattern that closely resembles its modern configuration. This drainage evolution was mainly controlled by tectonic deformation of the northeastern Tibetan Plateau, and enhancement in headwards erosion due to increased precipitation.</div></div>","PeriodicalId":55115,"journal":{"name":"Geomorphology","volume":"473 ","pages":"Article 109616"},"PeriodicalIF":3.1,"publicationDate":"2025-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143137962","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}
Pub Date : 2025-01-19DOI: 10.1016/j.geomorph.2025.109612
Diego A. Aguilar-Anaya , Carlos A. Mortera-Gutiérrez , Christian Berndt , William L. Bandy
Earthquakes can cause tsunamis by rapidly deforming the seafloor or triggering submarine slope failures. The intraplate earthquake in the Gulf of Tehuantepec on September 8, 2017 generated a tsunami that did not match the predicted tsunami run-up heights and distributions, indicating a possible additional slope failure. An oceanographic expedition, TEHUANTEPEC19, was carried out between May and June 2019, onboard the El Puma vessel, during which bathymetric, magnetic, and high-resolution seismic data were gathered and evaluated together with pre-existing seismic data. The results document a wide range of erosion-deposition processes in the region including past submarine landslides. However, the mapped landslide deposits are already heavily overprinted by gully formation and sedimentation, ruling out that submarine slumping influenced the recent tsunami after the 2017 Tehuantepec earthquake. Other geological processes, such as subsidence and extension of the forearc, large numbers of faults, and the subduction of the Tehuantepec Ridge, suggest that the Tehuantepec shelf is dominated by subduction erosion. This process may have deformed the continental shelf more complexly than assumed for the earthquake-derived tsunami model, explaining the mismatch between modeled and observed tsunamis. Our findings indicate that slope failure-induced tsunamis can play a role on the coasts of Central America, but this was not the case for the 2017 Tehuantepec earthquake.
{"title":"New insights into geomorphological and tectonic processes in the Gulf of Tehuantepec and constraints on tsunami generation","authors":"Diego A. Aguilar-Anaya , Carlos A. Mortera-Gutiérrez , Christian Berndt , William L. Bandy","doi":"10.1016/j.geomorph.2025.109612","DOIUrl":"10.1016/j.geomorph.2025.109612","url":null,"abstract":"<div><div>Earthquakes can cause tsunamis by rapidly deforming the seafloor or triggering submarine slope failures. The intraplate earthquake in the Gulf of Tehuantepec on September 8, 2017 generated a tsunami that did not match the predicted tsunami run-up heights and distributions, indicating a possible additional slope failure. An oceanographic expedition, TEHUANTEPEC19, was carried out between May and June 2019, onboard the El Puma vessel, during which bathymetric, magnetic, and high-resolution seismic data were gathered and evaluated together with pre-existing seismic data. The results document a wide range of erosion-deposition processes in the region including past submarine landslides. However, the mapped landslide deposits are already heavily overprinted by gully formation and sedimentation, ruling out that submarine slumping influenced the recent tsunami after the 2017 Tehuantepec earthquake. Other geological processes, such as subsidence and extension of the forearc, large numbers of faults, and the subduction of the Tehuantepec Ridge, suggest that the Tehuantepec shelf is dominated by subduction erosion. This process may have deformed the continental shelf more complexly than assumed for the earthquake-derived tsunami model, explaining the mismatch between modeled and observed tsunamis. Our findings indicate that slope failure-induced tsunamis can play a role on the coasts of Central America, but this was not the case for the 2017 Tehuantepec earthquake.</div></div>","PeriodicalId":55115,"journal":{"name":"Geomorphology","volume":"473 ","pages":"Article 109612"},"PeriodicalIF":3.1,"publicationDate":"2025-01-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143137796","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-19DOI: 10.1016/j.geomorph.2025.109613
Yanzai Wang , Yongqiu Wu
River longitudinal profiles are often smoothly concave up. Normalized Concavity Index (NCI) and concavity index () are usually used to quantify the degree of river concavity. These indices are calculated from distinct perspectives, and their interrelationships remain poorly understood. This study examines the relationships between NCI and in the Hulu River, a steady-state basin in the central Loess Plateau of China, using both all-channel and trunk-channel data. Landform evolution was modeled using Landlab to investigate changes in NCI and and their association. We find that (i) Due to the influence of tributary channels, NCI and are calculated using all channel data are larger than those for trunk channel data. calculated from all channels data may not effectively capture topographic implications, i.e., larger indicates more concave profiles. (ii) While NCI and derived from all-channel data show no significant correlation (P < 0.05), these concavity indices of trunk channels are significantly correlated (P < 0.05), indicating that tributary profiles may not be in a steady state even when trunk-channel profiles are in a steady state. (iii) Among model parameters, the drainage area exponent m in the stream power law strongly affects NCI and , and their correlations. However, it is important to note that the sensitivity analysis conducted in this study was relatively simple, and further in-depth analysis is needed to fully confirm the extent of the influence of m. Our results highlight the distinct behaviors of NCI and due to difference in their calculation methods and provide guidance for selecting suitable metrics for assessing river concavity.
{"title":"The topographic implications deduced from relationships between different river concavity indices","authors":"Yanzai Wang , Yongqiu Wu","doi":"10.1016/j.geomorph.2025.109613","DOIUrl":"10.1016/j.geomorph.2025.109613","url":null,"abstract":"<div><div>River longitudinal profiles are often smoothly concave up. Normalized Concavity Index (NCI) and concavity index (<span><math><mi>θ</mi></math></span>) are usually used to quantify the degree of river concavity. These indices are calculated from distinct perspectives, and their interrelationships remain poorly understood. This study examines the relationships between NCI and <span><math><mi>θ</mi></math></span> in the Hulu River, a steady-state basin in the central Loess Plateau of China, using both all-channel and trunk-channel data. Landform evolution was modeled using Landlab to investigate changes in NCI and <span><math><mi>θ</mi></math></span> and their association. We find that (i) Due to the influence of tributary channels, NCI and <span><math><mi>θ</mi></math></span> are calculated using all channel data are larger than those for trunk channel data. <span><math><mi>θ</mi></math></span> calculated from all channels data may not effectively capture topographic implications, i.e., larger <span><math><mi>θ</mi></math></span> indicates more concave profiles. (ii) While NCI and <span><math><mi>θ</mi></math></span> derived from all-channel data show no significant correlation (<em>P</em> < 0.05), these concavity indices of trunk channels are significantly correlated (<em>P</em> < 0.05), indicating that tributary profiles may not be in a steady state even when trunk-channel profiles are in a steady state. (iii) Among model parameters, the drainage area exponent <em>m</em> in the stream power law strongly affects NCI and <span><math><mi>θ</mi></math></span>, and their correlations. However, it is important to note that the sensitivity analysis conducted in this study was relatively simple, and further in-depth analysis is needed to fully confirm the extent of the influence of <em>m</em>. Our results highlight the distinct behaviors of NCI and <span><math><mi>θ</mi></math></span> due to difference in their calculation methods and provide guidance for selecting suitable metrics for assessing river concavity.</div></div>","PeriodicalId":55115,"journal":{"name":"Geomorphology","volume":"473 ","pages":"Article 109613"},"PeriodicalIF":3.1,"publicationDate":"2025-01-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143137797","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}
Pub Date : 2025-01-17DOI: 10.1016/j.geomorph.2025.109610
Bernard O. Bauer , Jeff Ollerhead , Irene Delgado-Fernandez , Robin G.D. Davidson-Arnott
Estimates of total sand volume in foredunes are commonly made for purposes of predicting coastal erosion and inundation potential during major storms, which is of critical importance for resource management and engineering purposes. However, changes in dune volume through time are potentially of greater relevance to process geomorphologists because volume changes are diagnostic of the long-term evolution of beach-dune systems and can be related to drivers of change (e.g., storm climatology, sediment supply, human action). The methods by which dune volume change estimates are made vary widely in the literature because there are no established protocols that provide guidance on the horizontal distances over which volume integration should be performed. In addition, identifying a diagnostic geomorphic feature such as the dune toe as a limit on integration is fraught with subjective uncertainties. In this paper, an objective methodology for quantifying dune volume change directly (rather than absolute volume) is proposed that is simple, intuitive, and robust. The horizontal limits of integration are identified by zero-crossings in the topographic change profiles between two transect surveys taken at different times, and this avoids challenges associated with identification of the dune toe as a fixed profile feature. Instead, the proposed method focuses on locations of morphodynamic significance where there has been a transition from erosion to accretion in the time interval between surveys.
{"title":"Analyzing topographic change profiles in coastal foredune systems: Methodological recommendations","authors":"Bernard O. Bauer , Jeff Ollerhead , Irene Delgado-Fernandez , Robin G.D. Davidson-Arnott","doi":"10.1016/j.geomorph.2025.109610","DOIUrl":"10.1016/j.geomorph.2025.109610","url":null,"abstract":"<div><div>Estimates of total sand volume in foredunes are commonly made for purposes of predicting coastal erosion and inundation potential during major storms, which is of critical importance for resource management and engineering purposes. However, changes in dune volume through time are potentially of greater relevance to process geomorphologists because volume changes are diagnostic of the long-term evolution of beach-dune systems and can be related to drivers of change (e.g., storm climatology, sediment supply, human action). The methods by which dune volume change estimates are made vary widely in the literature because there are no established protocols that provide guidance on the horizontal distances over which volume integration should be performed. In addition, identifying a diagnostic geomorphic feature such as the dune toe as a limit on integration is fraught with subjective uncertainties. In this paper, an objective methodology for quantifying dune volume change directly (rather than absolute volume) is proposed that is simple, intuitive, and robust. The horizontal limits of integration are identified by zero-crossings in the topographic change profiles between two transect surveys taken at different times, and this avoids challenges associated with identification of the dune toe as a fixed profile feature. Instead, the proposed method focuses on locations of morphodynamic significance where there has been a transition from erosion to accretion in the time interval between surveys.</div></div>","PeriodicalId":55115,"journal":{"name":"Geomorphology","volume":"472 ","pages":"Article 109610"},"PeriodicalIF":3.1,"publicationDate":"2025-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143160418","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}
Pub Date : 2025-01-17DOI: 10.1016/j.geomorph.2025.109611
Xiaoqing Ma , Changxing Shi , Huijuan Li , Wei Liu
Information on sediment sources in river basins is crucial for the rational distribution of soil and water conservation measures. The Yellow River in China has an overground channel in its downstream, which is prone to be breached during floods and has been elevated mainly by siltation of coarse particles in the river load. Soft sandstone strata underlaying an area in the middle reaches were found to be one of the principal coarse sediment sources of the river. Using a sediment fingerprinting mixing model with geochemical elements as tracers, we fingerprinted the changes in source apportionments from the region underlain by soft sandstone strata and the region with other substrata in the river basin in the past 2600 years. Source sediment samples were collected from the sediment deposits at the outlets of the main tributaries in the middle reaches, and target sediment samples were collected from alluvial fans in the lower reaches of the river. Geochemical properties of the samples were used as source fingerprints. Using the range test and Kruskal–Wallis H-test and considering the chemical reactivity of the tracer, five geochemical tracers were selected. The results showed that the sediment contribution (<63 μm) of the basins in the region underlain by soft sandstone strata was in the range of 4.2 %–56.0 %, 19.6 % on average. Combining the relative source contributions with the total river load in historical periods, the reconstructed sediment yields from both sources showed an increasing trend with time, but the increasing rate was lower in the region underlain by soft sandstone strata where human interference was weaker historically. This study can serve as a reference for sediment fingerprinting in large catchments, and our findings have implications for future water and soil conservation in the Yellow River basin.
{"title":"Late Holocene sediment source changes in the Yellow River basin, China","authors":"Xiaoqing Ma , Changxing Shi , Huijuan Li , Wei Liu","doi":"10.1016/j.geomorph.2025.109611","DOIUrl":"10.1016/j.geomorph.2025.109611","url":null,"abstract":"<div><div>Information on sediment sources in river basins is crucial for the rational distribution of soil and water conservation measures. The Yellow River in China has an overground channel in its downstream, which is prone to be breached during floods and has been elevated mainly by siltation of coarse particles in the river load. Soft sandstone strata underlaying an area in the middle reaches were found to be one of the principal coarse sediment sources of the river. Using a sediment fingerprinting mixing model with geochemical elements as tracers, we fingerprinted the changes in source apportionments from the region underlain by soft sandstone strata and the region with other substrata in the river basin in the past 2600 years. Source sediment samples were collected from the sediment deposits at the outlets of the main tributaries in the middle reaches, and target sediment samples were collected from alluvial fans in the lower reaches of the river. Geochemical properties of the samples were used as source fingerprints. Using the range test and Kruskal–Wallis H-test and considering the chemical reactivity of the tracer, five geochemical tracers were selected. The results showed that the sediment contribution (<63 μm) of the basins in the region underlain by soft sandstone strata was in the range of 4.2 %–56.0 %, 19.6 % on average. Combining the relative source contributions with the total river load in historical periods, the reconstructed sediment yields from both sources showed an increasing trend with time, but the increasing rate was lower in the region underlain by soft sandstone strata where human interference was weaker historically. This study can serve as a reference for sediment fingerprinting in large catchments, and our findings have implications for future water and soil conservation in the Yellow River basin.</div></div>","PeriodicalId":55115,"journal":{"name":"Geomorphology","volume":"472 ","pages":"Article 109611"},"PeriodicalIF":3.1,"publicationDate":"2025-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143160417","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}
Pub Date : 2025-01-16DOI: 10.1016/j.geomorph.2025.109609
Junki Komori, Rohan Gautam, Nurul Syafiqah Tan, Aron J. Meltzner
Coral microatolls track relative sea level (RSL) as they grow and can inform reconstructions of past RSL change, beyond the duration of instrumental observations. However, direct observation of coral growth history requires slabbing cross sections, which is destructive and logistically challenging. To address this complication, recent studies have explored analysis of coral surface morphologies using non-invasive methods. However, these methods are limited; they cannot directly access key features inside the corals that are indicative of past RSL change events. To overcome this limitation, we devised a method to formulate the growth pattern of massive corals through iteration to simulate coral growth in response to RSL changes. Additionally, we developed an alternative model that analytically approximates the same coral growth, suitable for stochastic analyses. To test the effectiveness of these models, we utilized observations of coral microatolls from Sumatra that emerged during the 2004 MW 9.1 earthquake. We first compared actual coral cross sections with coral geometries modeled using the respective RSL histories interpreted for those corals in previous studies. Next, we attempted to reconstruct past RSL history using only coral surface profiles with a stochastic inversion. The forward simulation presented an approximate reproduction of the actual corals, although there were discrepancies due to localized variations in growth rate. The inversion study approximately reproduced the previous interpretation of RSL history; however, the effect of nonuniform growth speed was not negligible. While these results highlight the necessity of a comprehensive understanding of coral growth for a more robust interpretation, the simulators developed in this study are powerful tools for improving this understanding.
{"title":"Simulation-based approach for reconstructing past relative sea-level changes using coral microatolls","authors":"Junki Komori, Rohan Gautam, Nurul Syafiqah Tan, Aron J. Meltzner","doi":"10.1016/j.geomorph.2025.109609","DOIUrl":"10.1016/j.geomorph.2025.109609","url":null,"abstract":"<div><div>Coral microatolls track relative sea level (RSL) as they grow and can inform reconstructions of past RSL change, beyond the duration of instrumental observations. However, direct observation of coral growth history requires slabbing cross sections, which is destructive and logistically challenging. To address this complication, recent studies have explored analysis of coral surface morphologies using non-invasive methods. However, these methods are limited; they cannot directly access key features inside the corals that are indicative of past RSL change events. To overcome this limitation, we devised a method to formulate the growth pattern of massive corals through iteration to simulate coral growth in response to RSL changes. Additionally, we developed an alternative model that analytically approximates the same coral growth, suitable for stochastic analyses. To test the effectiveness of these models, we utilized observations of coral microatolls from Sumatra that emerged during the 2004 <em>M</em><sub>W</sub> 9.1 earthquake. We first compared actual coral cross sections with coral geometries modeled using the respective RSL histories interpreted for those corals in previous studies. Next, we attempted to reconstruct past RSL history using only coral surface profiles with a stochastic inversion. The forward simulation presented an approximate reproduction of the actual corals, although there were discrepancies due to localized variations in growth rate. The inversion study approximately reproduced the previous interpretation of RSL history; however, the effect of nonuniform growth speed was not negligible. While these results highlight the necessity of a comprehensive understanding of coral growth for a more robust interpretation, the simulators developed in this study are powerful tools for improving this understanding.</div></div>","PeriodicalId":55115,"journal":{"name":"Geomorphology","volume":"473 ","pages":"Article 109609"},"PeriodicalIF":3.1,"publicationDate":"2025-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143137801","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-14DOI: 10.1016/j.geomorph.2025.109607
Mohammad Irfan , Bikram Singh Bali , Ahsan Afzal , Savaş Topal
<div><div>Alluvial fans are prominent geomorphic landforms that develop at the junction of mountain slopes and valley floors. This study investigates the morphological characteristics of alluvial fans along the Zanskar Shear Zone to identify the key variables influencing their development and morphodynamics. Despite being among the world's most significant semi-arid terrestrial fans, their morphology and controlling factors remain largely unexplored. Using advanced remote sensing and GIS techniques, combined with field investigations, we conducted a detailed spatial analysis of 37 fans, located on both sides of the Doda River. This approach enabled precise mapping and characterization of these fans within the complex depositional settings of the Doda Valley, particularly where fans coalesce into bajadas. Our analysis revealed significant variability in fan attributes, including Flow Expansion Angle (FEA), Fan Entrenchment (FME), Base length (BF), Fan Area (FA), Fan Slope (SF), and Radius (R). A morphometric analysis was then conducted to evaluate the correlation between the fans and their corresponding basins. To deepen this understanding, power law regression was applied, revealing both positive and negative relationships between fans and basin characteristics. The findings underscore the key role of upstream basins in regulating sediment delivery to the fans. Larger basins contribute to the development of larger, less steep fans, driven by higher sediment supply and greater flows from basins with denser drainage networks. Low values of Smf Index, Vf ratio and Drainage Basin Shape suggest that upstream basins are significantly influenced by tectonic forces. These forces result in linear mountain fronts, V-shaped valleys and elongated basins, indicative of active tectonic deformation. Along the mountain fronts of the Doda Valley, fan morphology is controlled by a complex interplay of long-term tectonic activity, climate, upstream lithology, and basin characteristics. Tectonic forces, particularly those associated with the NW-SE-trending ZSZ, exert a primary influence on fan morphology by controlling sediment-flux and accommodation space. This is evident in tectonically modified landforms, such as wine-glass valleys with narrow outlets, triangular facets with broad bases and active mountain fronts, all indicative of recent uplift and ongoing tectonic activity. These findings strongly suggest that tectonic structures like the ZSZ, which dips approximately 20° NE and continuously responds to tectonic collision, play a pivotal role in shaping fan morphodynamics. Additionally, climatic factors, such as increased glacial melt and freeze-thaw cycles, enhance erosion in upstream basins, particularly those fed by glaciers on the southwestern side of the valley. This process amplifies sediment supply to the fans, highlighting the dual influence of climate and tectonics in shaping regional fan systems. Overall, the findings demonstrate that ZSZ exert a domi
{"title":"Morphology and controls of the alluvial fan systems along the Zanskar Shear Zone, Northwest Himalaya, India","authors":"Mohammad Irfan , Bikram Singh Bali , Ahsan Afzal , Savaş Topal","doi":"10.1016/j.geomorph.2025.109607","DOIUrl":"10.1016/j.geomorph.2025.109607","url":null,"abstract":"<div><div>Alluvial fans are prominent geomorphic landforms that develop at the junction of mountain slopes and valley floors. This study investigates the morphological characteristics of alluvial fans along the Zanskar Shear Zone to identify the key variables influencing their development and morphodynamics. Despite being among the world's most significant semi-arid terrestrial fans, their morphology and controlling factors remain largely unexplored. Using advanced remote sensing and GIS techniques, combined with field investigations, we conducted a detailed spatial analysis of 37 fans, located on both sides of the Doda River. This approach enabled precise mapping and characterization of these fans within the complex depositional settings of the Doda Valley, particularly where fans coalesce into bajadas. Our analysis revealed significant variability in fan attributes, including Flow Expansion Angle (FEA), Fan Entrenchment (FME), Base length (BF), Fan Area (FA), Fan Slope (SF), and Radius (R). A morphometric analysis was then conducted to evaluate the correlation between the fans and their corresponding basins. To deepen this understanding, power law regression was applied, revealing both positive and negative relationships between fans and basin characteristics. The findings underscore the key role of upstream basins in regulating sediment delivery to the fans. Larger basins contribute to the development of larger, less steep fans, driven by higher sediment supply and greater flows from basins with denser drainage networks. Low values of Smf Index, Vf ratio and Drainage Basin Shape suggest that upstream basins are significantly influenced by tectonic forces. These forces result in linear mountain fronts, V-shaped valleys and elongated basins, indicative of active tectonic deformation. Along the mountain fronts of the Doda Valley, fan morphology is controlled by a complex interplay of long-term tectonic activity, climate, upstream lithology, and basin characteristics. Tectonic forces, particularly those associated with the NW-SE-trending ZSZ, exert a primary influence on fan morphology by controlling sediment-flux and accommodation space. This is evident in tectonically modified landforms, such as wine-glass valleys with narrow outlets, triangular facets with broad bases and active mountain fronts, all indicative of recent uplift and ongoing tectonic activity. These findings strongly suggest that tectonic structures like the ZSZ, which dips approximately 20° NE and continuously responds to tectonic collision, play a pivotal role in shaping fan morphodynamics. Additionally, climatic factors, such as increased glacial melt and freeze-thaw cycles, enhance erosion in upstream basins, particularly those fed by glaciers on the southwestern side of the valley. This process amplifies sediment supply to the fans, highlighting the dual influence of climate and tectonics in shaping regional fan systems. Overall, the findings demonstrate that ZSZ exert a domi","PeriodicalId":55115,"journal":{"name":"Geomorphology","volume":"472 ","pages":"Article 109607"},"PeriodicalIF":3.1,"publicationDate":"2025-01-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143160421","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}
Pub Date : 2025-01-13DOI: 10.1016/j.geomorph.2025.109606
Paúl Carrión-Mero , Mirka Arcentales-Rosado , María Jaya-Montalvo , Josué Briones-Bitar , Jairo Dueñas-Tovar , Ramón L. Espinel , Josep Mata-Perelló , Fernando Morante-Carballo
Galapagos Islands (Ecuador) have a unique and internationally recognized flora and fauna. However, despite its strict management framework focused on biotic heritage, understandable elements are needed to transmit geological and geomorphological knowledge to the public. Therefore, the integration of other values, such as geotourism and geoconservation, is an opportunity to improve local tourism, considering the geological history of the oldest area of the archipelago. This study aims to evaluate sites of geological interest and the proposal of geotourism routes on an island (San Cristóbal) under added approaches (e.g. geoeducation), using two international geosite evaluation methodologies, for the valorization of the geoheritage and its integration with the present ecotourism. The workflow included i) analysis and selection of sites, ii) semi-quantitative assessment, and iii) proposals for management strategies. Twelve sites were classified into four typologies of geological/geomorphological domain, where scientific, cultural, and tourist values exceeded 60 % of the total score. Laguna “El Junco” stands out, as it combines volcanic elements (extinct crater) and ecological values (e.g. frigates). “Cerro Quemado” presented a high risk of degradation, given its extractive activity that influences the volcanic landscape of interest to visitors (cinder cones). Simultaneously, the identified weaknesses were the low cultural appropriation of natural elements. Thus, the research proposed four routes with natural and cultural value for the development of geotourism, influenced by Charles Darwin's expedition aboard the Beagle in 1835. Finally, this work showed how geotourism and geoeducation could enrich the framework of “research-oriented” tourism in island-protected areas, as exhibited in similar regions worldwide. For this purpose, it was crucial to design interpretive panels showing the geological importance with tangible and intangible values that configure the island as a World Heritage Site and their links with the cultural elements of the area.
{"title":"Assessment of geosites and geotouristic routes proposal for geoheritage promotion on volcanic islands","authors":"Paúl Carrión-Mero , Mirka Arcentales-Rosado , María Jaya-Montalvo , Josué Briones-Bitar , Jairo Dueñas-Tovar , Ramón L. Espinel , Josep Mata-Perelló , Fernando Morante-Carballo","doi":"10.1016/j.geomorph.2025.109606","DOIUrl":"10.1016/j.geomorph.2025.109606","url":null,"abstract":"<div><div>Galapagos Islands (Ecuador) have a unique and internationally recognized flora and fauna. However, despite its strict management framework focused on biotic heritage, understandable elements are needed to transmit geological and geomorphological knowledge to the public. Therefore, the integration of other values, such as geotourism and geoconservation, is an opportunity to improve local tourism, considering the geological history of the oldest area of the archipelago. This study aims to evaluate sites of geological interest and the proposal of geotourism routes on an island (San Cristóbal) under added approaches (e.g. geoeducation), using two international geosite evaluation methodologies, for the valorization of the geoheritage and its integration with the present ecotourism. The workflow included i) analysis and selection of sites, ii) semi-quantitative assessment, and iii) proposals for management strategies. Twelve sites were classified into four typologies of geological/geomorphological domain, where scientific, cultural, and tourist values exceeded 60 % of the total score. Laguna “El Junco” stands out, as it combines volcanic elements (extinct crater) and ecological values (e.g. frigates). “Cerro Quemado” presented a high risk of degradation, given its extractive activity that influences the volcanic landscape of interest to visitors (cinder cones). Simultaneously, the identified weaknesses were the low cultural appropriation of natural elements. Thus, the research proposed four routes with natural and cultural value for the development of geotourism, influenced by Charles Darwin's expedition aboard the Beagle in 1835. Finally, this work showed how geotourism and geoeducation could enrich the framework of “research-oriented” tourism in island-protected areas, as exhibited in similar regions worldwide. For this purpose, it was crucial to design interpretive panels showing the geological importance with tangible and intangible values that configure the island as a World Heritage Site and their links with the cultural elements of the area.</div></div>","PeriodicalId":55115,"journal":{"name":"Geomorphology","volume":"472 ","pages":"Article 109606"},"PeriodicalIF":3.1,"publicationDate":"2025-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143161261","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}
Pub Date : 2025-01-13DOI: 10.1016/j.geomorph.2025.109605
Yingying Cui , Yali Zhou , Zhibao Dong , Ivan Lizaga , Ping Lü , Jiale Wang
Understanding the provenance of aeolian loess is crucial for gaining insights into dust transport processes, atmospheric circulation, and climate change. The loess in the upper Hanjiang River (UHR), situated between the Qinling and Daba Mountains, acts as a natural divide between northern and southern China. Identifying and quantifying the sources of loess in the UHR are essential for elucidating the mechanisms of Asian dust release. This study used grain-size and heavy mineral analysis to determine whether the loess on the UHR's first terrace primarily originates from proximal or distant sources. We quantified the contributions of these sources using advanced techniques such as the Conservativeness Index (CI) and Consensus Ranking (CR). Our findings revealed that the UHR loess was mainly derived from weathered materials from the proximal Qinling-Daba Mountains, accounting for 62 ± 3 %. The weathered materials from the proximal Qinling-Daba Mountains to be stored in the floodplains. Subsequently, they were deposited on the river terraces by the mountain valley winds. The Chinese Loess Plateau, representing the distant-source arid inland in northwest China, contributes 38 ± 3 %, primarily through fine particles that dust storms elevate thousands of meters into the atmosphere, and the East Asian winter monsoon transports across long distances, eventually depositing them into the UHR after crossing the Qinling Mountains. However, the sources of UHR loess varied geographically. The Hanzhong Basin and Yunxian Basin predominantly received materials from proximal sources, whereas the Ankang Basin was primarily supplied by distant source materials. This difference spatial variation in loess provenance is likely to be influenced by a combination of rivers, monsoons, and mountain ranges. In conclusion, unlike the loess of the Chinese Loess Plateau, which predominantly originates from the arid inland region of northwest China, the UHR loess is primarily derived from weathered products of the proximal Qinling Mountains. This study demonstrates that the CI, CR models constitute an effective approach for quantitative provenance research in loess.
{"title":"Quantitative analysis the provenance of loess in the upper Hanjiang River, China: Evidence from heavy minerals and grain-size","authors":"Yingying Cui , Yali Zhou , Zhibao Dong , Ivan Lizaga , Ping Lü , Jiale Wang","doi":"10.1016/j.geomorph.2025.109605","DOIUrl":"10.1016/j.geomorph.2025.109605","url":null,"abstract":"<div><div>Understanding the provenance of aeolian loess is crucial for gaining insights into dust transport processes, atmospheric circulation, and climate change. The loess in the upper Hanjiang River (UHR), situated between the Qinling and Daba Mountains, acts as a natural divide between northern and southern China. Identifying and quantifying the sources of loess in the UHR are essential for elucidating the mechanisms of Asian dust release. This study used grain-size and heavy mineral analysis to determine whether the loess on the UHR's first terrace primarily originates from proximal or distant sources. We quantified the contributions of these sources using advanced techniques such as the Conservativeness Index (CI) and Consensus Ranking (CR). Our findings revealed that the UHR loess was mainly derived from weathered materials from the proximal Qinling-Daba Mountains, accounting for 62 ± 3 %. The weathered materials from the proximal Qinling-Daba Mountains to be stored in the floodplains. Subsequently, they were deposited on the river terraces by the mountain valley winds. The Chinese Loess Plateau, representing the distant-source arid inland in northwest China, contributes 38 ± 3 %, primarily through fine particles that dust storms elevate thousands of meters into the atmosphere, and the East Asian winter monsoon transports across long distances, eventually depositing them into the UHR after crossing the Qinling Mountains. However, the sources of UHR loess varied geographically. The Hanzhong Basin and Yunxian Basin predominantly received materials from proximal sources, whereas the Ankang Basin was primarily supplied by distant source materials. This difference spatial variation in loess provenance is likely to be influenced by a combination of rivers, monsoons, and mountain ranges. In conclusion, unlike the loess of the Chinese Loess Plateau, which predominantly originates from the arid inland region of northwest China, the UHR loess is primarily derived from weathered products of the proximal Qinling Mountains. This study demonstrates that the CI, CR models constitute an effective approach for quantitative provenance research in loess.</div></div>","PeriodicalId":55115,"journal":{"name":"Geomorphology","volume":"472 ","pages":"Article 109605"},"PeriodicalIF":3.1,"publicationDate":"2025-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143161191","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}