The dependence of the subduction regime on three-dimensional slab geometry poses a challenge for accurately estimating the evolving thermal structure of megathrusts globally. Although slab dips and ages have gained at...The dependence of the subduction regime on three-dimensional slab geometry poses a challenge for accurately estimating the evolving thermal structure of megathrusts globally. Although slab dips and ages have gained attention, the specific impacts of oblique subduction remain unmeasured. Here, we present an integrated thermal model that quantifies how slab morphology can shape the thermal state of megathrusts, such as those in the Makran Subduction Zone. The model considers both slab obliquity and depth variations along the trench. We find a considerable match between the slab petrological dehydration zone and the distribution of great crustal earthquakes. We suggest that the accumulation of fluids along megathrusts by slab metamorphism can foster more polarized conditions for decreasing plate coupling and increasing interplate ruptures. It is thus imperative to improve model representation and more realistically represent how drivers of slab geometry affect metamorphic transitions and the occurrence of earthquakes at megathrusts.展开更多
We investigated the relationships among slab geometry, obliquity, and the thermal regime associated with the subduction of oceanic plates using a three-dimensional （3D） parallelepiped thermal convection model. Vario...We investigated the relationships among slab geometry, obliquity, and the thermal regime associated with the subduction of oceanic plates using a three-dimensional （3D） parallelepiped thermal convection model. Various models with convex and concave slab shapes were constructed in the numerical simu- lation, and the temperature and mantle flow distributions were calculated. The results revealed that when the slab dip angle increases, or the obliquity of subduction becomes steeper, the interplate tem- perature decreases remarkably. Cooler （warmer） zones on the plate interface were identified from the modeling where there was a larger （smaller） subduction angle. Consequently, the interplate temperature distribution is partly controlled by the true subduction angle （TSA）, which is a function of the slab dip angle and the obliquity of subduction. The rate of change of the interface temperature for the TSA was 10-50 ℃ （10°〈 TSA 〈 20°） at depths ranging from （TSA 10） × 5 km to 60 ＋ （TSA 10） × 5 km for a fiat slab after a subduction history of 7 Myrs. The along-arc slab curvature affects the variation in TSA. The slab radius also appeared to influence the radius of induced mantle flow.展开更多
To provide a seepage-stress coupling constitutive model that can directly describe the seepage-stress coupling relationship, a series of one-dimensional seepage-stress coupling tests on two kinds of soft rock (argilla...To provide a seepage-stress coupling constitutive model that can directly describe the seepage-stress coupling relationship, a series of one-dimensional seepage-stress coupling tests on two kinds of soft rock (argillaceous siltstone and brown mudstone) were performed by using an MTS-815.02 tri-axial rock mechanics test system, with which the stress-strain curves according to the seepage variation were obtained. Based on the experimental results and by employing Hooke's law, the formulation of the coefficient of strain-dependent permeability was presented and introduced to establish a coupling model. In addition, the mathematical expression and the incremental formulation for coupling model were advanced, in which five parameters that can be respectively determined by using the experimental results were included. The calculated results show that the proposed coupling model is capable of simulating the stress-strain relationship with considering the seepage-stress coupling in the nonlinear elastic stage of two kinds of soft rock.展开更多
Debris flow triggered by rainfall that accompanies a volcanic eruption is a serious secondary impact of a volcanic disaster.The probability of debris flow events can be estimated based on the prior information of rain...Debris flow triggered by rainfall that accompanies a volcanic eruption is a serious secondary impact of a volcanic disaster.The probability of debris flow events can be estimated based on the prior information of rainfall from historical and geomorphological data that are presumed to relate to debris flow occurrence.In this study,a debris flow disaster warning system was developed by applying the Na?¨ve Bayes Classifier(NBC).The spatial likelihood of the hazard is evaluated at a small subbasin scale by including high-resolution rainfall measurements from X-band polarimetric weather radar,a topographic factor,and soil type as predictors.The study was conducted in the Gendol River Basin of Mount Merapi,one of the most active volcanoes in Indonesia.Rainfall and debris flow occurrence data were collected for the upper Gendol River from October 2016 to February 2018 and divided into calibration and validation datasets.The NBC was used to estimate the status of debris flow incidences displayed in the susceptibility map that is based on the posterior probability from the predictors.The system verification was performed by quantitative dichotomous quality indices along with a contingency table.Using the validation datasets,the advantage of the NBC for estimating debris flow occurrence is confirmed.This work contributes to existing knowledge on estimating debris flow susceptibility through the data mining approach.Despite the existence of predictive uncertainty,the presented system could contribute to the improvement of debris flow countermeasures in volcanic regions.展开更多
This study analyzes data on households' risk perception and protective behavior following a natural disaster triggered technological accident(Natech accident)that occurred at an industrial park in Sendai during th...This study analyzes data on households' risk perception and protective behavior following a natural disaster triggered technological accident(Natech accident)that occurred at an industrial park in Sendai during the Great East Japan Earthquake and Tsunami, on 11 March2011. The results indicate that some households carried out multiple evacuations and that households' risk perceptions changed throughout the Natech accident evacuation process. Risk perception differed according to household location and demographic characteristics. We also found differences in the protective measures adopted for households in different locations. Specifically, those living closer to the Natech accident tended to evacuate immediately,whereas those living further away tended to shelter in place. Wind direction is discussed as a factor that influences households' risk perception and evacuation response to a Natech accident. The findings of this study advance knowledge of household behavior in response to a Natech accident and can assist emergency managers in developing strategies for better management of evacuation processes.展开更多
The present work explains the statics of self-weight transmission restricted to a long prismatic heap inclined at an angle of repose and symmetrically formed on a rigid base. The closure of polarized principal axes wi...The present work explains the statics of self-weight transmission restricted to a long prismatic heap inclined at an angle of repose and symmetrically formed on a rigid base. The closure of polarized principal axes with the mobilized state of stress along the slope surface is employed by imposing the orientation of principal stresses on the equilibrium equations. Comparisons were made with calculations based on the finite element method using an elastic model. Moreover, experiments on sand heaps deposited on a rectangular rigid base were conducted to validate the theoretical study. The measured pressure profile generally agreed well with theoretical results.展开更多
基金benefited from the financial support of the Chinese Academy of Sciences Pioneer Hundred Talents Programthe Second Tibetan Plateau Scientific Expedition and Research Program (Grant No. 2019QZKK0708)+2 种基金the MEXT KAKENHI grant (Grant No. 21H05203)the Kobe University Strategic International Collaborative Research Grant (Type B Fostering Joint Research)the “Science of Slowto-Fast Earthquakes” project。
文摘The dependence of the subduction regime on three-dimensional slab geometry poses a challenge for accurately estimating the evolving thermal structure of megathrusts globally. Although slab dips and ages have gained attention, the specific impacts of oblique subduction remain unmeasured. Here, we present an integrated thermal model that quantifies how slab morphology can shape the thermal state of megathrusts, such as those in the Makran Subduction Zone. The model considers both slab obliquity and depth variations along the trench. We find a considerable match between the slab petrological dehydration zone and the distribution of great crustal earthquakes. We suggest that the accumulation of fluids along megathrusts by slab metamorphism can foster more polarized conditions for decreasing plate coupling and increasing interplate ruptures. It is thus imperative to improve model representation and more realistically represent how drivers of slab geometry affect metamorphic transitions and the occurrence of earthquakes at megathrusts.
文摘We investigated the relationships among slab geometry, obliquity, and the thermal regime associated with the subduction of oceanic plates using a three-dimensional （3D） parallelepiped thermal convection model. Various models with convex and concave slab shapes were constructed in the numerical simu- lation, and the temperature and mantle flow distributions were calculated. The results revealed that when the slab dip angle increases, or the obliquity of subduction becomes steeper, the interplate tem- perature decreases remarkably. Cooler （warmer） zones on the plate interface were identified from the modeling where there was a larger （smaller） subduction angle. Consequently, the interplate temperature distribution is partly controlled by the true subduction angle （TSA）, which is a function of the slab dip angle and the obliquity of subduction. The rate of change of the interface temperature for the TSA was 10-50 ℃ （10°〈 TSA 〈 20°） at depths ranging from （TSA 10） × 5 km to 60 ＋ （TSA 10） × 5 km for a fiat slab after a subduction history of 7 Myrs. The along-arc slab curvature affects the variation in TSA. The slab radius also appeared to influence the radius of induced mantle flow.
基金Projects(50378069, 50639090) supported by the National Natural Science Foundation of ChinaProject(50639090) supported by the Joint Fund of Yalong River Hydropower Development, China
文摘To provide a seepage-stress coupling constitutive model that can directly describe the seepage-stress coupling relationship, a series of one-dimensional seepage-stress coupling tests on two kinds of soft rock (argillaceous siltstone and brown mudstone) were performed by using an MTS-815.02 tri-axial rock mechanics test system, with which the stress-strain curves according to the seepage variation were obtained. Based on the experimental results and by employing Hooke's law, the formulation of the coefficient of strain-dependent permeability was presented and introduced to establish a coupling model. In addition, the mathematical expression and the incremental formulation for coupling model were advanced, in which five parameters that can be respectively determined by using the experimental results were included. The calculated results show that the proposed coupling model is capable of simulating the stress-strain relationship with considering the seepage-stress coupling in the nonlinear elastic stage of two kinds of soft rock.
基金supported by the Science and Technology Research Partnership for Sustainable Development(SATREPS)Japan Science and Technology Agency(JST)the Japan International Cooperation Agency(JICA)
文摘Debris flow triggered by rainfall that accompanies a volcanic eruption is a serious secondary impact of a volcanic disaster.The probability of debris flow events can be estimated based on the prior information of rainfall from historical and geomorphological data that are presumed to relate to debris flow occurrence.In this study,a debris flow disaster warning system was developed by applying the Na?¨ve Bayes Classifier(NBC).The spatial likelihood of the hazard is evaluated at a small subbasin scale by including high-resolution rainfall measurements from X-band polarimetric weather radar,a topographic factor,and soil type as predictors.The study was conducted in the Gendol River Basin of Mount Merapi,one of the most active volcanoes in Indonesia.Rainfall and debris flow occurrence data were collected for the upper Gendol River from October 2016 to February 2018 and divided into calibration and validation datasets.The NBC was used to estimate the status of debris flow incidences displayed in the susceptibility map that is based on the posterior probability from the predictors.The system verification was performed by quantitative dichotomous quality indices along with a contingency table.Using the validation datasets,the advantage of the NBC for estimating debris flow occurrence is confirmed.This work contributes to existing knowledge on estimating debris flow susceptibility through the data mining approach.Despite the existence of predictive uncertainty,the presented system could contribute to the improvement of debris flow countermeasures in volcanic regions.
文摘This study analyzes data on households' risk perception and protective behavior following a natural disaster triggered technological accident(Natech accident)that occurred at an industrial park in Sendai during the Great East Japan Earthquake and Tsunami, on 11 March2011. The results indicate that some households carried out multiple evacuations and that households' risk perceptions changed throughout the Natech accident evacuation process. Risk perception differed according to household location and demographic characteristics. We also found differences in the protective measures adopted for households in different locations. Specifically, those living closer to the Natech accident tended to evacuate immediately,whereas those living further away tended to shelter in place. Wind direction is discussed as a factor that influences households' risk perception and evacuation response to a Natech accident. The findings of this study advance knowledge of household behavior in response to a Natech accident and can assist emergency managers in developing strategies for better management of evacuation processes.
基金supported by KAKENHI Grant Numbers 23760441 and 24360193The authors would like to expresstheir gratitude to Japan Society for the Promotion of Science(JSPS)
文摘The present work explains the statics of self-weight transmission restricted to a long prismatic heap inclined at an angle of repose and symmetrically formed on a rigid base. The closure of polarized principal axes with the mobilized state of stress along the slope surface is employed by imposing the orientation of principal stresses on the equilibrium equations. Comparisons were made with calculations based on the finite element method using an elastic model. Moreover, experiments on sand heaps deposited on a rectangular rigid base were conducted to validate the theoretical study. The measured pressure profile generally agreed well with theoretical results.
