Pub Date : 2023-11-23DOI: 10.1186/s40677-023-00259-0
Teraphan Ornthammarath, Amorntep Jirasakjamroonsri, Patinya Pornsopin, Rajesh Rupakhety, Nakhorn Poovarodom, Pennung Warnitchai, Tun Tun Tha Toe
The Bangkok Basin has been known from non-instrumental observations of the local population to be subject to ground motion amplification due to the deep alluvial sediments and basin geometry. This study analyzes available seismic data to confirm that basin effects are significant in the Bangkok Basin. The paper contributes to the evaluation of basin effects by characterizing the engineering ground motion parameters and HVSR curves for the Bangkok basin which produce lengthening of ground motion duration with respect to nearby rock sites, albeit with very low ground motions. For this purpose, we analyzed ground motion records from seismic stations located within the Bangkok alluvial basin from 2007 to 2021. Recorded peak horizontal ground acceleration (PGA) for seismic stations inside the basin always exceeded 1 cm/s2 during eight earthquakes with Mw ≥ 5.5. Of these, two were intraslab events and six were shallow crustal earthquakes. These recorded ground motions shook high-rise buildings in Bangkok even though their epicentral distance exceeded 600 km. Several time and frequency domain analyses (such as analysis of residual, HVSR, Hodogram plots, etc.) are used on the ground motion records in the Bangkok basin to determine the frequency content of recorded ground motion and to demonstrate the significance of surface waves induced by the deep basin in altering the engineering ground motion amplitudes. In addition, centerless circular array microtremor analysis is used to determine the depth of sedimentary basin to the bedrock. Based on comparisons from those stations located outside the Bangkok basin, we observed the capability of alluvial deposits in the Bangkok basin to amplify ground motion records by about 3 times. We observed that there is a unique site amplification effect between 0.3 and 0.1 Hz due to local surface waves and other moderate amplifications between 2 and 0.5 Hz due to a soft layer like other deep alluvial basins in other metropolitan areas. We noticed that there is a unique site amplification effect between 0.1 and 0.3 Hz and smaller peaks around 2 and 0.5 Hz consistent with expectations for site amplification effects associated with deep basins. Moreover, we noticed the presence of low frequencies content of the surface wave generated within the basin which deserved further studies using the 2D/3D ground motion modelling through basin topography and velocity models.
{"title":"Preliminary analysis of amplified ground motion in Bangkok basin using HVSR curves from recent moderate to large earthquakes","authors":"Teraphan Ornthammarath, Amorntep Jirasakjamroonsri, Patinya Pornsopin, Rajesh Rupakhety, Nakhorn Poovarodom, Pennung Warnitchai, Tun Tun Tha Toe","doi":"10.1186/s40677-023-00259-0","DOIUrl":"https://doi.org/10.1186/s40677-023-00259-0","url":null,"abstract":"The Bangkok Basin has been known from non-instrumental observations of the local population to be subject to ground motion amplification due to the deep alluvial sediments and basin geometry. This study analyzes available seismic data to confirm that basin effects are significant in the Bangkok Basin. The paper contributes to the evaluation of basin effects by characterizing the engineering ground motion parameters and HVSR curves for the Bangkok basin which produce lengthening of ground motion duration with respect to nearby rock sites, albeit with very low ground motions. For this purpose, we analyzed ground motion records from seismic stations located within the Bangkok alluvial basin from 2007 to 2021. Recorded peak horizontal ground acceleration (PGA) for seismic stations inside the basin always exceeded 1 cm/s2 during eight earthquakes with Mw ≥ 5.5. Of these, two were intraslab events and six were shallow crustal earthquakes. These recorded ground motions shook high-rise buildings in Bangkok even though their epicentral distance exceeded 600 km. Several time and frequency domain analyses (such as analysis of residual, HVSR, Hodogram plots, etc.) are used on the ground motion records in the Bangkok basin to determine the frequency content of recorded ground motion and to demonstrate the significance of surface waves induced by the deep basin in altering the engineering ground motion amplitudes. In addition, centerless circular array microtremor analysis is used to determine the depth of sedimentary basin to the bedrock. Based on comparisons from those stations located outside the Bangkok basin, we observed the capability of alluvial deposits in the Bangkok basin to amplify ground motion records by about 3 times. We observed that there is a unique site amplification effect between 0.3 and 0.1 Hz due to local surface waves and other moderate amplifications between 2 and 0.5 Hz due to a soft layer like other deep alluvial basins in other metropolitan areas. We noticed that there is a unique site amplification effect between 0.1 and 0.3 Hz and smaller peaks around 2 and 0.5 Hz consistent with expectations for site amplification effects associated with deep basins. Moreover, we noticed the presence of low frequencies content of the surface wave generated within the basin which deserved further studies using the 2D/3D ground motion modelling through basin topography and velocity models.","PeriodicalId":37025,"journal":{"name":"Geoenvironmental Disasters","volume":null,"pages":null},"PeriodicalIF":4.8,"publicationDate":"2023-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138534557","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-15DOI: 10.1186/s40677-023-00257-2
She Fangtao, Xu Wanying, Liu Lele, Liu Guoping, Li Lei, Duan Changhui
Uneven settlement will occur as a result of the collapsible deformation of the loess strata, and the hydraulic tunnel lining structure will also fail. In this work, laterally confined compression tests were carried out on loess and the double-line method was employed to evaluate the loess collapsibility. The deformation of the surrounding rock of a loess hydraulic tunnel under various ground stresses and its effect on the lining structure was modeled. Three stages were noted in the collapsible deformation of loess. The critical point between the former two stages corresponds to the pre-consolidation pressure of saturated loess and that between the latter two is taken as the structural yield pressure of unsaturated loess. From the relationship between the collapsibility coefficient and vertical stress, the deformation of the tunnel under ground seepage primarily originates from two sources, i.e., the collapsible and compressive deformation. The latter source accounts for the deformation of loess adjacent to the lining when the seepage depth is low, while both sources are included when the bottom of the tunnel invert is infiltrated. The collapsible deformation is lower than that of the original stratum due to the stress relaxation during tunnel excavation. The tensile and compressive stresses of tunnel lining increase linearly with the seepage depth, with the maximum appearing at a position of 20 m away from the midline of the collapse and non-collapse domains. The results will provide a theoretical reference to the design and construction of hydraulic tunnels in collapsible loess stratum.
{"title":"Evaluation of the collapsible deformation of surrounding rock of loess hydraulic tunnel considering ground stress variation","authors":"She Fangtao, Xu Wanying, Liu Lele, Liu Guoping, Li Lei, Duan Changhui","doi":"10.1186/s40677-023-00257-2","DOIUrl":"https://doi.org/10.1186/s40677-023-00257-2","url":null,"abstract":"Uneven settlement will occur as a result of the collapsible deformation of the loess strata, and the hydraulic tunnel lining structure will also fail. In this work, laterally confined compression tests were carried out on loess and the double-line method was employed to evaluate the loess collapsibility. The deformation of the surrounding rock of a loess hydraulic tunnel under various ground stresses and its effect on the lining structure was modeled. Three stages were noted in the collapsible deformation of loess. The critical point between the former two stages corresponds to the pre-consolidation pressure of saturated loess and that between the latter two is taken as the structural yield pressure of unsaturated loess. From the relationship between the collapsibility coefficient and vertical stress, the deformation of the tunnel under ground seepage primarily originates from two sources, i.e., the collapsible and compressive deformation. The latter source accounts for the deformation of loess adjacent to the lining when the seepage depth is low, while both sources are included when the bottom of the tunnel invert is infiltrated. The collapsible deformation is lower than that of the original stratum due to the stress relaxation during tunnel excavation. The tensile and compressive stresses of tunnel lining increase linearly with the seepage depth, with the maximum appearing at a position of 20 m away from the midline of the collapse and non-collapse domains. The results will provide a theoretical reference to the design and construction of hydraulic tunnels in collapsible loess stratum.","PeriodicalId":37025,"journal":{"name":"Geoenvironmental Disasters","volume":null,"pages":null},"PeriodicalIF":4.8,"publicationDate":"2023-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138534549","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-03DOI: 10.1186/s40677-023-00255-4
Ma Xuetong, Li Tonglu, Li Qipeng, Wang Changsheng, Gao Debin, Zhang Hao, Li Changhu
Abstract Background Reservoir bank collapse in loess areas may lead to the siltation of reservoir and bank retreat. Therefore, the study of reservoir bank collapse has practical significance. Almost of the bank collapse width prediction method were based on the classical graphical method which do not consider the process of bank collapse. But practice shows that this method can overestimate the width of bank collapse. Meanwhile, there are few studies specifically focused on the collapse of loess bank slopes. Methods To improve the prediction method of loss bank collapse width, the influence of water depth, dry density and bank slope angle on loess bank collapse was studied by physical modelling. The bank collapse width and the morphology of the bank slope were recorded during the experiment. Results The bank collapse width increases with the increase of water depth, increases with the increase of slope angle, and decreases with the increase of dry density. The modeling process shows that the loess bank collapse occurs firstly underwater, the erosion niche will be formed underwater, and then the above water slope is damaged. This process is repeated until the underwater accumulation slope reaches the stable state, and then bank collapse stops. After the bank collapse, the above water slope is polyline, while the underwater slope is curved. When the slope angle is less than 27°, the bank collapse will not occur, and when the slope angle is between 27° and 40°, the bank collapse type is abrasion type. When the slope angle is greater than 40°, the bank collapse type is dumping type or shear type. Based on this, the improved balanced alluvial accumulation approach was proposed, which considers the mechanical equilibrium of above water bank slope and the morphology of underwater slope. The new method can reflect the stage characteristics of loess bank collapse, which is more reasonable than the empirical graphical method. Conclusions The experimental results indicate that when predicting the width of loess bank collapse, it is necessary to combine the bank collapse width and process of bank collapse. The relevant conclusions have a certain role in exploring the mechanism of loess bank collapse and bank collapse prediction methods.
{"title":"Study on the influencing factors and evolution of loess bank collapse with physical modelling","authors":"Ma Xuetong, Li Tonglu, Li Qipeng, Wang Changsheng, Gao Debin, Zhang Hao, Li Changhu","doi":"10.1186/s40677-023-00255-4","DOIUrl":"https://doi.org/10.1186/s40677-023-00255-4","url":null,"abstract":"Abstract Background Reservoir bank collapse in loess areas may lead to the siltation of reservoir and bank retreat. Therefore, the study of reservoir bank collapse has practical significance. Almost of the bank collapse width prediction method were based on the classical graphical method which do not consider the process of bank collapse. But practice shows that this method can overestimate the width of bank collapse. Meanwhile, there are few studies specifically focused on the collapse of loess bank slopes. Methods To improve the prediction method of loss bank collapse width, the influence of water depth, dry density and bank slope angle on loess bank collapse was studied by physical modelling. The bank collapse width and the morphology of the bank slope were recorded during the experiment. Results The bank collapse width increases with the increase of water depth, increases with the increase of slope angle, and decreases with the increase of dry density. The modeling process shows that the loess bank collapse occurs firstly underwater, the erosion niche will be formed underwater, and then the above water slope is damaged. This process is repeated until the underwater accumulation slope reaches the stable state, and then bank collapse stops. After the bank collapse, the above water slope is polyline, while the underwater slope is curved. When the slope angle is less than 27°, the bank collapse will not occur, and when the slope angle is between 27° and 40°, the bank collapse type is abrasion type. When the slope angle is greater than 40°, the bank collapse type is dumping type or shear type. Based on this, the improved balanced alluvial accumulation approach was proposed, which considers the mechanical equilibrium of above water bank slope and the morphology of underwater slope. The new method can reflect the stage characteristics of loess bank collapse, which is more reasonable than the empirical graphical method. Conclusions The experimental results indicate that when predicting the width of loess bank collapse, it is necessary to combine the bank collapse width and process of bank collapse. The relevant conclusions have a certain role in exploring the mechanism of loess bank collapse and bank collapse prediction methods.","PeriodicalId":37025,"journal":{"name":"Geoenvironmental Disasters","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135819438","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract Introduction The rock avalanches are a frequent and disruptive phenomenon in the Himalayas and other mountain chains. To minimize future losses, it is essential to investigate the engineering geological causative factors and mechanism of these mass wasting events. Study area The present work is aimed at assessing the failure mechanism of the disastrous 2014 Jure rock avalanche along Araniko Highway, Northern Nepal. The event had blocked the Sunkoshi River and blocked an economically significant route to China. Geotechnical properties and analysis Initially, rockmass characterization and intact strength attribute were determined for the site to classify the failure zone. The parameters measured and obtained from the field and laboratory were integrated into the analytical models to obtain a conclusive interpretation of the failure mechanism. Structural, kinematic, and key block theory analyses have been carried out for decipher the evolution of the failure zone. Results and discussion Rock mass was found to be of fair quality, however, the structural instabilities and the presence of water has led to a progressive failure. Movement of the key block and subsequent sliding of wedges and foot failure appears to be a possible failure mechanism. Conclusion The present research explores the contributory engineering geological aspects of the Jure rock avalanche. The investigation results can be used to tackle similar large scale rock avalanches in similar geological terrains and thus minimizing the losses.
{"title":"Engineering geological characteristics and failure mechanics of Jure rock avalanche, Nepal","authors":"Suman Panthee, Suman Dulal, Vishnu Himanshu Ratnam Pandey, Vikas Yadav, Prakash Kumar Singh, Ashutosh Kainthola","doi":"10.1186/s40677-023-00256-3","DOIUrl":"https://doi.org/10.1186/s40677-023-00256-3","url":null,"abstract":"Abstract Introduction The rock avalanches are a frequent and disruptive phenomenon in the Himalayas and other mountain chains. To minimize future losses, it is essential to investigate the engineering geological causative factors and mechanism of these mass wasting events. Study area The present work is aimed at assessing the failure mechanism of the disastrous 2014 Jure rock avalanche along Araniko Highway, Northern Nepal. The event had blocked the Sunkoshi River and blocked an economically significant route to China. Geotechnical properties and analysis Initially, rockmass characterization and intact strength attribute were determined for the site to classify the failure zone. The parameters measured and obtained from the field and laboratory were integrated into the analytical models to obtain a conclusive interpretation of the failure mechanism. Structural, kinematic, and key block theory analyses have been carried out for decipher the evolution of the failure zone. Results and discussion Rock mass was found to be of fair quality, however, the structural instabilities and the presence of water has led to a progressive failure. Movement of the key block and subsequent sliding of wedges and foot failure appears to be a possible failure mechanism. Conclusion The present research explores the contributory engineering geological aspects of the Jure rock avalanche. The investigation results can be used to tackle similar large scale rock avalanches in similar geological terrains and thus minimizing the losses.","PeriodicalId":37025,"journal":{"name":"Geoenvironmental Disasters","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136157096","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-10-27DOI: 10.1186/s40677-023-00253-6
Shoulong Ma, Mingwei Zhang, Lu Ma, Zhuangcai Tian, Xue Li, Zhenhao Su, Sicheng Bian
Abstract Coal mining has a significant impact on the movement of the overburden, leading to potential safety hazards in the working face. In this paper, a similarity simulation experiment was conducted to investigate the migration of overburden during the mining process of a specific working face in the Liuzhuang Coal Mine located in southern China. Sand and gravel were used to simulate the geological environment of each rock stratum. The deformation of the stratum was monitored using strain gauges, the fracture and displacement changes of the overburden stratum were recorded using cameras, and the characteristics of roof collapse was monitored using infrared thermal imager. The experimental model fully simulated the situation of the working face, and the actual working face size was obtained by enlarging the model by 100 times. The experiment found that during the initial stage of mining, there was no significant subsidence of the roof. In the course of the advancement of the working face, the primary roof intermittently fractured behind the working face, with subsequent propagation of upper cracks in an upward direction. The overburden rock layer above the goaf experienced continuous compaction, leading to the gradual closure of the separation layer. Simultaneously, new cracks constantly emerged in front of the working face, resulting in the progressive stabilization of the height of the crack zone. The stress measurements at each point exhibit a pattern of initial increased, followed by decrease, and ultimately stabilization. By considering the stress variation law of the overburden rock, the stress changes in key layers of the bedrock during mining could be categorized into four zones: the stress stable zone, stress increasing zone, stress reducing zone, and compaction stable zone. During the initial phase of coal seam mining, the presence of rock layers provided support, resulting in minimal subsidence of the overburden rock. However, as the mining operation progressed, the disturbance force and collapse of the overburden rock leaded to further downward subsidence. When the working face reached the stop line, the collapsed overburden rock gradually consolidates, resulting in a deceleration of energy release and the formation of a pressure relief zone. Consequently, the overburden rock above the working face underwent a slight additional subsidence, reaching its maximum level. A short cantilever rock beam structure was formed in the experiment. This study will provide valuable reference for future coal mining and serve as a vital theoretical basis for roof control in deep coal seam mining.
{"title":"Experimental investigation on stress distribution and migration of the overburden during the mining process in deep coal seam mining","authors":"Shoulong Ma, Mingwei Zhang, Lu Ma, Zhuangcai Tian, Xue Li, Zhenhao Su, Sicheng Bian","doi":"10.1186/s40677-023-00253-6","DOIUrl":"https://doi.org/10.1186/s40677-023-00253-6","url":null,"abstract":"Abstract Coal mining has a significant impact on the movement of the overburden, leading to potential safety hazards in the working face. In this paper, a similarity simulation experiment was conducted to investigate the migration of overburden during the mining process of a specific working face in the Liuzhuang Coal Mine located in southern China. Sand and gravel were used to simulate the geological environment of each rock stratum. The deformation of the stratum was monitored using strain gauges, the fracture and displacement changes of the overburden stratum were recorded using cameras, and the characteristics of roof collapse was monitored using infrared thermal imager. The experimental model fully simulated the situation of the working face, and the actual working face size was obtained by enlarging the model by 100 times. The experiment found that during the initial stage of mining, there was no significant subsidence of the roof. In the course of the advancement of the working face, the primary roof intermittently fractured behind the working face, with subsequent propagation of upper cracks in an upward direction. The overburden rock layer above the goaf experienced continuous compaction, leading to the gradual closure of the separation layer. Simultaneously, new cracks constantly emerged in front of the working face, resulting in the progressive stabilization of the height of the crack zone. The stress measurements at each point exhibit a pattern of initial increased, followed by decrease, and ultimately stabilization. By considering the stress variation law of the overburden rock, the stress changes in key layers of the bedrock during mining could be categorized into four zones: the stress stable zone, stress increasing zone, stress reducing zone, and compaction stable zone. During the initial phase of coal seam mining, the presence of rock layers provided support, resulting in minimal subsidence of the overburden rock. However, as the mining operation progressed, the disturbance force and collapse of the overburden rock leaded to further downward subsidence. When the working face reached the stop line, the collapsed overburden rock gradually consolidates, resulting in a deceleration of energy release and the formation of a pressure relief zone. Consequently, the overburden rock above the working face underwent a slight additional subsidence, reaching its maximum level. A short cantilever rock beam structure was formed in the experiment. This study will provide valuable reference for future coal mining and serve as a vital theoretical basis for roof control in deep coal seam mining.","PeriodicalId":37025,"journal":{"name":"Geoenvironmental Disasters","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136317404","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-10-19DOI: 10.1186/s40677-023-00251-8
Yu Huang, Wuwei Mao, Min Xiong, Yian Wang, Cuizhu Zhao, Zhengying He, Fawu Wang
Abstract The International Workshop on Seismic Design and Assessment for Resilience, Robustness and Sustainability of Slope Engineering was held on 13–15 January 2023 on line, focusing on the theme of “Seismic resilience of slope engineering and the concept of resilience-based seismic design (RBSD) for geological disaster prevention and control”. In this workshop, a number of keynote and invited lectures provided an international exchange platform for researchers, industrial engineers and students to share their research, engineering practice and exchange novel ideas on seismic resilience for slope engineering in a way of online. At the same time, during this workshop, technical committee of the ICGdR-TC1 also took this opportunity to hold a working meeting on cutting-edge and strategic issues, and released the Shanghai Declaration on slope engineering.
{"title":"Report on the international workshop on seismic design and assessment for resilience, robustness and sustainability of slope engineering, 13–15 January 2023, Shanghai, China","authors":"Yu Huang, Wuwei Mao, Min Xiong, Yian Wang, Cuizhu Zhao, Zhengying He, Fawu Wang","doi":"10.1186/s40677-023-00251-8","DOIUrl":"https://doi.org/10.1186/s40677-023-00251-8","url":null,"abstract":"Abstract The International Workshop on Seismic Design and Assessment for Resilience, Robustness and Sustainability of Slope Engineering was held on 13–15 January 2023 on line, focusing on the theme of “Seismic resilience of slope engineering and the concept of resilience-based seismic design (RBSD) for geological disaster prevention and control”. In this workshop, a number of keynote and invited lectures provided an international exchange platform for researchers, industrial engineers and students to share their research, engineering practice and exchange novel ideas on seismic resilience for slope engineering in a way of online. At the same time, during this workshop, technical committee of the ICGdR-TC1 also took this opportunity to hold a working meeting on cutting-edge and strategic issues, and released the Shanghai Declaration on slope engineering.","PeriodicalId":37025,"journal":{"name":"Geoenvironmental Disasters","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135730375","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-10-13DOI: 10.1186/s40677-023-00254-5
Alfred Homère Ngandam Mfondoum, Pauline Wokwenmendam Nguet, Dieudonné Tchokona Seuwui, Jean Valéry Mefire Mfondoum, Henry Bang Ngenyam, Ibrahima Diba, Mesmin Tchindjang, Bertin Djiangoue, Ali Mihi, Sofia Hakdaoui, Roseline Batcha, Frédéric Chamberlain Lounang Tchatchouang, Igor Casimir Njombissie Petcheu, Luc Moutila Beni
Abstract Background The Cameroon Volcanic Line (CVL) is an oceanic-continental megastructure prone to geo-hazards, including landslide/mudslide, gully erosion and flash floods targeted in this paper. Recent geospatial practices advocated a multi-hazard analysis approach supported by artificial intelligence. This study proposes the Multi-Geoenvironmental Hazards Susceptibility (MGHS) tool, by combining Analytical Hierarchy Process (AHP) with Machine Learning (ML) over the North-Moungo perimeter (Littoral Region, Cameroon). Methods Twenty-four factors were constructed from satellite imagery, global geodatabase and fieldwork data. Multicollinearity among these factors was quantified using the tolerance coefficient (TOL) and variance inflation factor (VIF). The AHP coefficients were used to weigh the factors and produce a preliminary map per Geoenvironmental hazard through weighted linear combination (WLC). The sampling was conducted based on events records and analyst knowledge to proceed with classification using Google Earth Engine (GEE) cloud computing interface. Classification and Regression Trees (CART), Random Forest (RF) and Gradient Boosting Regression Trees (GBRT), were used as basic learners of the stacked hazard factors, whereas, Support Vector Regression (SVR), was used for a meta-learning. Results The rainfall was ranked as the highest triggering factor for all Geoenvironmental hazards according to AHP, with a coefficient of 1 , while the after-learning importance assessment was more varied. The area under receiver operating characteristic (AUROC/AUC) was always more than 0.96 , and F 1 -score is between [ 0.86–0.88 ] for basic classifiers. Landslides, gully erosion and flash floods showed different spatial distributions, confirming then their probability of co-occurrence. MGHS outputs clearly displayed two and three simultaneous occurrences. Finally, the human vulnerability assessed with population layer and SVR outputs showed that high human concentrations are also the most exposed, using the example of Nkongsamba’s extract. Conclusions Combining AHP with single learners, then a meta-learner, was efficient in modelling MGHS and related human vulnerability. Interactions among geo-environmental hazards are the next step and city councils are recommended to integrate results in the planning process.
{"title":"Stepwise integration of analytical hierarchy process with machine learning algorithms for landslide, gully erosion and flash flood susceptibility mapping over the North-Moungo perimeter, Cameroon","authors":"Alfred Homère Ngandam Mfondoum, Pauline Wokwenmendam Nguet, Dieudonné Tchokona Seuwui, Jean Valéry Mefire Mfondoum, Henry Bang Ngenyam, Ibrahima Diba, Mesmin Tchindjang, Bertin Djiangoue, Ali Mihi, Sofia Hakdaoui, Roseline Batcha, Frédéric Chamberlain Lounang Tchatchouang, Igor Casimir Njombissie Petcheu, Luc Moutila Beni","doi":"10.1186/s40677-023-00254-5","DOIUrl":"https://doi.org/10.1186/s40677-023-00254-5","url":null,"abstract":"Abstract Background The Cameroon Volcanic Line (CVL) is an oceanic-continental megastructure prone to geo-hazards, including landslide/mudslide, gully erosion and flash floods targeted in this paper. Recent geospatial practices advocated a multi-hazard analysis approach supported by artificial intelligence. This study proposes the Multi-Geoenvironmental Hazards Susceptibility (MGHS) tool, by combining Analytical Hierarchy Process (AHP) with Machine Learning (ML) over the North-Moungo perimeter (Littoral Region, Cameroon). Methods Twenty-four factors were constructed from satellite imagery, global geodatabase and fieldwork data. Multicollinearity among these factors was quantified using the tolerance coefficient (TOL) and variance inflation factor (VIF). The AHP coefficients were used to weigh the factors and produce a preliminary map per Geoenvironmental hazard through weighted linear combination (WLC). The sampling was conducted based on events records and analyst knowledge to proceed with classification using Google Earth Engine (GEE) cloud computing interface. Classification and Regression Trees (CART), Random Forest (RF) and Gradient Boosting Regression Trees (GBRT), were used as basic learners of the stacked hazard factors, whereas, Support Vector Regression (SVR), was used for a meta-learning. Results The rainfall was ranked as the highest triggering factor for all Geoenvironmental hazards according to AHP, with a coefficient of 1 , while the after-learning importance assessment was more varied. The area under receiver operating characteristic (AUROC/AUC) was always more than 0.96 , and F 1 -score is between [ 0.86–0.88 ] for basic classifiers. Landslides, gully erosion and flash floods showed different spatial distributions, confirming then their probability of co-occurrence. MGHS outputs clearly displayed two and three simultaneous occurrences. Finally, the human vulnerability assessed with population layer and SVR outputs showed that high human concentrations are also the most exposed, using the example of Nkongsamba’s extract. Conclusions Combining AHP with single learners, then a meta-learner, was efficient in modelling MGHS and related human vulnerability. Interactions among geo-environmental hazards are the next step and city councils are recommended to integrate results in the planning process.","PeriodicalId":37025,"journal":{"name":"Geoenvironmental Disasters","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135853952","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-10-11DOI: 10.1186/s40677-023-00252-7
None Benazir, None Syamsidik, Yunita Idris, Nadri Pratama Putra
Abstract This paper reflects on the progress of tsunami preparedness in a coastal community in Aceh, Indonesia, nearly two decades after the catastrophic 2004 Indian Ocean Tsunami. The research employs a comprehensive approach to thoroughly evaluate and comprehend the community’s preparedness, its correlation with local perceptions of tsunami risk, and delves into the prevalence of tsunamis in the area, with a specific emphasis on the significant impact of the 2004 Indian Ocean Tsunami on the coastal community of Aceh. To investigate the community’s readiness and the potential impacts of tsunamis at the study site, tsunami simulations were performed using the shallow water equation within the COMCOT (Cornell Multi-grid Coupled Tsunami) model. These simulations assessed run-up and inundation scenarios, thereby providing justification for the potential tsunami impact in the area. Modelling the scenario of tsunami in the region is important to measure the potential impact and estimation time for community to prepare the evacuation plan. In addition to the numerical modeling, a mixed-method approach was employed, involving the distribution of questionnaires and conducting in-depth interviews with 150 respondents directly on-site. These assessments yielded valuable insights into community perspectives on tsunami risk and their preparedness measures. The findings contribute to the development of effective strategies for disaster management by integrating local knowledge, experiences, and socialization programs. The study emphasizes the significance of ongoing endeavors to enhance community preparedness and mitigate the consequences of tsunamis.
{"title":"Connecting community’s perspectives on tsunami risk to anticipated future tsunamis: a reflection from a progress of tsunami preparedness from a coastal community in Aceh-Indonesia after 19 years of the 2004 Indian Ocean Tsunami","authors":"None Benazir, None Syamsidik, Yunita Idris, Nadri Pratama Putra","doi":"10.1186/s40677-023-00252-7","DOIUrl":"https://doi.org/10.1186/s40677-023-00252-7","url":null,"abstract":"Abstract This paper reflects on the progress of tsunami preparedness in a coastal community in Aceh, Indonesia, nearly two decades after the catastrophic 2004 Indian Ocean Tsunami. The research employs a comprehensive approach to thoroughly evaluate and comprehend the community’s preparedness, its correlation with local perceptions of tsunami risk, and delves into the prevalence of tsunamis in the area, with a specific emphasis on the significant impact of the 2004 Indian Ocean Tsunami on the coastal community of Aceh. To investigate the community’s readiness and the potential impacts of tsunamis at the study site, tsunami simulations were performed using the shallow water equation within the COMCOT (Cornell Multi-grid Coupled Tsunami) model. These simulations assessed run-up and inundation scenarios, thereby providing justification for the potential tsunami impact in the area. Modelling the scenario of tsunami in the region is important to measure the potential impact and estimation time for community to prepare the evacuation plan. In addition to the numerical modeling, a mixed-method approach was employed, involving the distribution of questionnaires and conducting in-depth interviews with 150 respondents directly on-site. These assessments yielded valuable insights into community perspectives on tsunami risk and their preparedness measures. The findings contribute to the development of effective strategies for disaster management by integrating local knowledge, experiences, and socialization programs. The study emphasizes the significance of ongoing endeavors to enhance community preparedness and mitigate the consequences of tsunamis.","PeriodicalId":37025,"journal":{"name":"Geoenvironmental Disasters","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136063316","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-09-28DOI: 10.1186/s40677-023-00250-9
Michael Nones, Yiwei Guo
Abstract Background Climate change and increasing anthropogenic pressure are two of the major drivers of increasing extreme events like droughts and floods. To deal with the increasing number of flooding events hitting Europe in the last few decades, around twenty years ago the European Commission started to develop ad-hoc legislation to reduce flood risk by mapping flood hazard and risk areas, such as the Directive 2007/60/EC on the Assessment and Management of Flood Risk. This Directive looks to identify regions where flood management strategies should be prioritized. Despite this holistic approach, flaws connected to the consideration of sediment transport and morphological changes in rivers exist, leading to potential underestimations of the impact of floods affecting active watercourses or areas subjected to frequent morphological changes. Results By discussing six examples related to European lowland and mountain watercourses affected by significant floods in the last 20 years, the present mini-review aims to provide additional evidence on the need for a rethinking of flood risk mapping, moving from a “clear water” perspective to a more integrated approach, where the interactions between all the fluvial components (water, sediment, biota, and humans) are adequately considered. Conclusions The examples reported here show the importance of considering sediment and wood in flood risk management, suggesting the need for integrating flood-related studies with other disciplines like geomorphology and ecohydrology.
{"title":"Can sediments play a role in river flood risk mapping? Learning from selected European examples","authors":"Michael Nones, Yiwei Guo","doi":"10.1186/s40677-023-00250-9","DOIUrl":"https://doi.org/10.1186/s40677-023-00250-9","url":null,"abstract":"Abstract Background Climate change and increasing anthropogenic pressure are two of the major drivers of increasing extreme events like droughts and floods. To deal with the increasing number of flooding events hitting Europe in the last few decades, around twenty years ago the European Commission started to develop ad-hoc legislation to reduce flood risk by mapping flood hazard and risk areas, such as the Directive 2007/60/EC on the Assessment and Management of Flood Risk. This Directive looks to identify regions where flood management strategies should be prioritized. Despite this holistic approach, flaws connected to the consideration of sediment transport and morphological changes in rivers exist, leading to potential underestimations of the impact of floods affecting active watercourses or areas subjected to frequent morphological changes. Results By discussing six examples related to European lowland and mountain watercourses affected by significant floods in the last 20 years, the present mini-review aims to provide additional evidence on the need for a rethinking of flood risk mapping, moving from a “clear water” perspective to a more integrated approach, where the interactions between all the fluvial components (water, sediment, biota, and humans) are adequately considered. Conclusions The examples reported here show the importance of considering sediment and wood in flood risk management, suggesting the need for integrating flood-related studies with other disciplines like geomorphology and ecohydrology.","PeriodicalId":37025,"journal":{"name":"Geoenvironmental Disasters","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135386742","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-09-06DOI: 10.1186/s40677-023-00249-2
Alemayehu Letamo, B. Kavitha, T. P. Tezeswi
{"title":"Unified earthquake catalogue and mapping of Gutenberg–Richter parameters for the East African Rift System","authors":"Alemayehu Letamo, B. Kavitha, T. P. Tezeswi","doi":"10.1186/s40677-023-00249-2","DOIUrl":"https://doi.org/10.1186/s40677-023-00249-2","url":null,"abstract":"","PeriodicalId":37025,"journal":{"name":"Geoenvironmental Disasters","volume":null,"pages":null},"PeriodicalIF":4.8,"publicationDate":"2023-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41449239","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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