Pub Date : 1900-01-01DOI: 10.5026/JGEOGRAPHY.118.1160
M. Sunamura, T. Noguchi, Hiroyuki Yamamoto, K. Okamura
Hydrothermal circulations supply a huge amount of chemical species into the deep sea. More than 99% of chemical species emitted from high-temperature hydrothermal fluids flow into the deep sea and construct deep-sea hydrothermal plumes. Observations of hydrothermal plumes have led studies of deep-sea hydrothermal vents, such as locating deep-sea hydrothermal vents, locating deep-sea volcanic eruptions, and calculating geochemical fluxes from sub-seafloor to deep ocean. Hydrothermal plumes affect the microbial community in deep seas by supplying many reduced chemicals, which are possible energy sources of chemolithotrophic microbes. This paper (1) reviews physical, chemical, biological studies of hydrothermal plumes and (2) discusses novel field survey technology and ecological infection of sub-seafloor to the deep-sea environment.
{"title":"Environmental and Ecological Impact on Deep-sea Environment from Deep-sea Hydrothermal System","authors":"M. Sunamura, T. Noguchi, Hiroyuki Yamamoto, K. Okamura","doi":"10.5026/JGEOGRAPHY.118.1160","DOIUrl":"https://doi.org/10.5026/JGEOGRAPHY.118.1160","url":null,"abstract":"Hydrothermal circulations supply a huge amount of chemical species into the deep sea. More than 99% of chemical species emitted from high-temperature hydrothermal fluids flow into the deep sea and construct deep-sea hydrothermal plumes. Observations of hydrothermal plumes have led studies of deep-sea hydrothermal vents, such as locating deep-sea hydrothermal vents, locating deep-sea volcanic eruptions, and calculating geochemical fluxes from sub-seafloor to deep ocean. Hydrothermal plumes affect the microbial community in deep seas by supplying many reduced chemicals, which are possible energy sources of chemolithotrophic microbes. This paper (1) reviews physical, chemical, biological studies of hydrothermal plumes and (2) discusses novel field survey technology and ecological infection of sub-seafloor to the deep-sea environment.","PeriodicalId":356213,"journal":{"name":"Chigaku Zasshi (jounal of Geography)","volume":"87 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121281311","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 : 1900-01-01DOI: 10.5026/JGEOGRAPHY.119.378
Y. Isozaki, S. Maruyama, S. Yanai
A new historical review is presented on the progress of the geological sciences in Japan since the Meiji revolution in 1868. Geological knowledge, particularly studies of the geotectonic evolution and orogenic aspects, of the Japanese Islands has progressed through three distinct phases; (1) non-science stage, (2) colonial science stage, and (3) independent science stage, as modeled by Basalla (1967), who demonstrated a general pattern of transplanting cutting-edge scientific/technological knowledge from western Europe to the rest of the world. During the “non-science” stage from the 1860s to the 1890s, major geological aspects of the Japanese Islands, together with discoveries of unusual rocks, fossils etc., were initially described by foreign geologists (e.g. E. Naumann). In contrast, almost nothing was contributed by domestic geologists. During the “colonial science” stage, from the 1900s to the 1980s, research and education systems were transplanted effectively from western European countries. For example, applying the purely imported concept of geosyncline, the geotectonic history of the Japanese Islands was summarized for the first time by domestic geologists (e.g., Kobayashi, 1941; Minato et al., 1965 etc.). The almost unidirectional acceptance of plate tectonics also followed at this stage, with the exception of the rare but outstanding contribution of A. Miyashiro during the 1960s-1970s. During the “independent science” stage from the 1980s, various new ideas and original techniques in geology were proposed by Japanese geologists with lesser help from the western countries than before; i.e., practical criteria for identifying ancient accretionary complex, exhumation tectonic of ultrahigh to high-P/T metamorphic rocks, and subhorizontal growth framework of subduction-related orogens. Furthermore, in the first decade of the 21st century, the geological science in Japan entered stage of (4), “exporting science” with the introduction of new paradigms, such as the application of detrital zircon chronology to subduction-related orogens, which efficiently recognizes new geotectonic subdivisions and allows paleogeographical reconstruction with much higher resolution than before. These new paradigms (ideas, techniques) from Japan are now on sale for applying to the rest of the world.
本文对明治维新以来日本地质科学的发展进行了新的历史回顾。日本诸岛的地质知识，特别是对大地构造演化和造山方面的研究，经历了三个不同的阶段;(1)非科学阶段，(2)殖民科学阶段，(3)独立科学阶段，以Basalla(1967)为模型，他展示了从西欧向世界其他地区移植尖端科学/技术知识的一般模式。在19世纪60年代至90年代的“非科学”阶段，日本列岛的主要地质方面，连同不寻常的岩石、化石等的发现，最初是由外国地质学家(如E. Naumann)描述的。相比之下，国内地质学家几乎没有贡献。在20世纪90年代至80年代的“殖民科学”阶段，研究和教育系统有效地从西欧国家移植过来。例如，国内地质学家首次运用纯引进的地槽概念，对日本列岛大地构造史进行了总结(如Kobayashi, 1941;Minato et al.， 1965等)。在这一阶段，除了A. Miyashiro在20世纪60年代至70年代的罕见而杰出的贡献外，板块构造论也几乎被单向地接受。20世纪80年代以来的“独立科学”阶段，日本地质学家在西方国家的帮助有所减少的情况下，提出了地质学的各种新思想和新技术;即识别古增生杂岩的实用标准、超高至高p /T变质岩的发掘构造、俯冲相关造山带的亚水平生长格架。21世纪前10年，日本地质科学进入了“输出科学”阶段，引入了新的范式，如将碎屑锆石年代学应用于与俯冲有关的造山带，有效地识别了新的大地构造细分，使古地理重建的分辨率大大提高。这些来自日本的新范例(思想、技术)现在正在出售，以应用到世界其他地方。
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Pub Date : 1900-01-01DOI: 10.5026/JGEOGRAPHY.118.III
H. Numanami, R. Matsumoto
{"title":"Pictorial 3: Sea-floor Environment and Benthos of Methane Seep Area","authors":"H. Numanami, R. Matsumoto","doi":"10.5026/JGEOGRAPHY.118.III","DOIUrl":"https://doi.org/10.5026/JGEOGRAPHY.118.III","url":null,"abstract":"","PeriodicalId":356213,"journal":{"name":"Chigaku Zasshi (jounal of Geography)","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121622756","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 : 1900-01-01DOI: 10.5026/JGEOGRAPHY.119.313
K. Aoki, S. Otoh, S. Yanai, S. Maruyama
The Sanbagawa metamorphic belt in SW Japan was previously considered to extend in the E-W direction from the Kanto Mountains to Kyushu Island, a distance > 800 km. However, Aoki et al. (2007) recently demonstrated that protoliths of metamorphic rocks in the Oboke area of the belt in central Shikoku accumulated at the trench after ca. 90-80 Ma. Furthermore, Aoki et al. (2008) showed that these rocks suffered blueschist metamorphism at 66-61 Ma, which differs from the timing of the Sanbagawa metamorphism. Thus, these results show that the Sanbagawa belt in Shikoku is a composite metamorphic belt. We, therefore, redefine the traditional Sanbagawa belt; the structurally upper part is the Sanbagawa metamorphic belt (sensu stricto). It formed as an accretionary complex at ca. 140-130 Ma and subsequently experienced BS-EC facies metamorphism at ca. 120-110 Ma (Okamoto et al., 2004). By contrast, the structurally lower segment termed the Shimanto BS facies metamorphic belt, formed as an accretionary complex after ca. 90-80 Ma and experienced peak metamorphism at ca. 60 Ma. Our observations have important implications for the lateral extension of these two metamorphic belts in SW Japan. The accretionary ages of the traditional Sanbagawa belt in the Kanto Mountains are younger than the Sanbagawa peak metamorphic age (Tsutsumi et al., 2009), clearly indicating that the entire region of Kanto Mountains Sanbagawa must belong to the Shimanto metamorphic belt. The same timing relationships were also found for the Sanbagawa belt on Kii Peninsula (Otoh et al., 2010). These results, therefore, indicate that the Shimanto metamorphic belt is exposed in Shikoku, Kii, and Kanto, thus the spatial distribution of Sanbagawa belt (ss) is less than half of its previous extent. The metamorphic grade of the Kanto Mountains in the Shimanto metamorphic belt ranges from pumpellyite-actinolite facies to epidote-amphibolite facies. Therefore, the higher-grade rocks of the Shimanto metamorphic rocks are exposed in the Kanto Mountains in comparison with Shikoku and Kii Peninsula. Hence, these two distinct BS-EA-EC (?) metamorphic belts are virtually equivalent in terms of spatial distribution, metamorphic range of grade, and facies series. Pacific-type orogenic belts typically comprise accretionary complex, high-P/T metamorphic belt, fore-arc sediments, and batholith belt landward from the trench (Maruyama et al., 1996). In SW Japan, the Sanbagawa belt (ss) is paired with the Ryoke low-P/T metamorphic belt and with the ca. 120-70 Ma Sanyo TTG batholith belt. Furthermore the related fore-arc basin may have developed penecontemporaneously with the Shimanto BS-EA orogeny, which is paired with the late Cretaceous to early Tertiary San-in TTG belt, which extending along the Japan Sea coast. In-between the intervening Izumi Group, a fore-arc basin deposit formed during the Campanian to Maastrichtian. Thus, these two groups of orogenic units, which formed during independent orogenies were
日本西南部的三川变质带以前被认为是从关东山脉向东西向延伸到九州岛，距离约800公里。然而，Aoki et al.(2007)最近表明，在大约90-80 Ma之后，四国中部奥博克地区的变质岩原岩在海沟内聚集。此外，Aoki et al.(2008)表明，这些岩石在66-61 Ma遭受蓝片岩变质作用，这与三巴川变质作用的时间不同。结果表明，四国三巴川带为复合变质带。因此，我们重新定义了传统的三川带;构造上部为三巴川变质带(严格意义上)。它形成于约140-130 Ma的增生杂岩，随后在约120-110 Ma经历了BS-EC相变质作用(Okamoto et al.， 2004)。下部构造段为石曼托- BS相变质带，形成于约90 ~ 80 Ma的增生杂岩，约60 Ma变质作用达到顶峰。我们的观测结果对日本西南部这两条变质带的横向伸展具有重要意义。关东山传统三巴川带的增生年龄小于三巴川峰变质年龄(Tsutsumi et al.， 2009)，这清楚地表明关东山三巴川整个地区必须属于岛曼东变质带。Kii半岛的Sanbagawa带也发现了相同的时间关系(Otoh et al.， 2010)。这些结果表明，岛东变质带在四国、喜井和关东暴露，因此三巴川变质带的空间分布范围不到以前的一半。石曼托变质带关东山脉的变质等级从泵柱岩—放光石相到绿帘岩—角闪岩相不等。因此，相对于四国半岛和喜井半岛，在关东山脉出露的是岛曼东变质岩中品位较高的岩石。因此，这两个不同的BS-EA-EC(?)变质带在空间分布、变质等级范围和相系列上几乎是相同的。太平洋型造山带通常包括增生杂岩、高p /T变质带、弧前沉积物和从海沟向陆的基带(Maruyama et al.， 1996)。在日本西南部，三川带与Ryoke低p /T变质带和约120 ~ 70 Ma Sanyo TTG基带配对。弧前盆地可能与石曼托BS-EA造山带发育准同时，与晚白垩世至早第三纪三叠统TTG带相对应，并沿日本海海岸延伸。在其间的泉群之间，形成了坎帕纪到马斯特里赫特纪的弧前盆地沉积。由此可见，这两组独立造山时期形成的造山单元，均在20 Ma左右的日本海开闭期间发生了大规模改造。良川带和白垩系TTG带在三巴川上的南向逆冲延伸超出了三巴川的南缘，导致了三巴川带和良川带的上下关系。
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Pub Date : 1900-01-01DOI: 10.5026/JGEOGRAPHY.117.424
Daichi Nakayama, D. Morinaga, H. Matsuyama
This study analyzes runoff and inundation flow to reproduce the condition of the August 1993 flood that occurred in the upper reaches of Sendai River in the northern part of Kagoshima prefecture, and determines model parameters. Besides, the case of situation more serious than the past floods were assumed, and it is estimated whether the inhabitants could take refuge by traveling on foot on flooded roads to evacuation centers. In the runoff analysis, the distributed runoff model based on the kinematic wave model was used. A Gridded Digital Elevation Model （ DEM ） , 50 m resolution was used to provide terrain data and flood runoff was calculated with the Drainage Direction Matrix （ DDM ） extracted from DEM. Past discharge hydrographs were fairly well reproduced by the runoff analysis. In the inundation flow analysis, a 2-dimensional unsteady flow model based on the dynamic wave model was used to calculate the expansion of the inundation flow. In the inundation flow analysis, the order of water depth was reproduced well in comparison to actual inundation, however, the estimated inundation area was smaller than the actual one. Next, runoff and inundation flow analyses were carried out with the modeled rainfall, which was more serious than that of past floods, using the model parameters determined above. The simulated flooded areas were almost the same as those caused by torrential rain in August 1993, however, the water was deeper. The current velocity was high just after the area flooded, but it slowed after 1 to 2 hours to about 0.05 m/sec in most of the flooded areas. traveling so inhabitants could not take refuge there on foot unless they took refuge at early stage of the flood. Whether or not inhabitants could take refuge safely on foot largely depended on their height, and the areas where they could walk safely was limited by their height.
{"title":"Evaluation of the Evacuation Route Availability Based on an Inundation Flow Simulation","authors":"Daichi Nakayama, D. Morinaga, H. Matsuyama","doi":"10.5026/JGEOGRAPHY.117.424","DOIUrl":"https://doi.org/10.5026/JGEOGRAPHY.117.424","url":null,"abstract":"This study analyzes runoff and inundation flow to reproduce the condition of the August 1993 flood that occurred in the upper reaches of Sendai River in the northern part of Kagoshima prefecture, and determines model parameters. Besides, the case of situation more serious than the past floods were assumed, and it is estimated whether the inhabitants could take refuge by traveling on foot on flooded roads to evacuation centers. In the runoff analysis, the distributed runoff model based on the kinematic wave model was used. A Gridded Digital Elevation Model （ DEM ） , 50 m resolution was used to provide terrain data and flood runoff was calculated with the Drainage Direction Matrix （ DDM ） extracted from DEM. Past discharge hydrographs were fairly well reproduced by the runoff analysis. In the inundation flow analysis, a 2-dimensional unsteady flow model based on the dynamic wave model was used to calculate the expansion of the inundation flow. In the inundation flow analysis, the order of water depth was reproduced well in comparison to actual inundation, however, the estimated inundation area was smaller than the actual one. Next, runoff and inundation flow analyses were carried out with the modeled rainfall, which was more serious than that of past floods, using the model parameters determined above. The simulated flooded areas were almost the same as those caused by torrential rain in August 1993, however, the water was deeper. The current velocity was high just after the area flooded, but it slowed after 1 to 2 hours to about 0.05 m/sec in most of the flooded areas. traveling so inhabitants could not take refuge there on foot unless they took refuge at early stage of the flood. Whether or not inhabitants could take refuge safely on foot largely depended on their height, and the areas where they could walk safely was limited by their height.","PeriodicalId":356213,"journal":{"name":"Chigaku Zasshi (jounal of Geography)","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125758707","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 : 1900-01-01DOI: 10.5026/JGEOGRAPHY.119.668
Y. Niwa, T. Sugai, T. Ogami, Masayoshi Tajikara, K. Yasue, O. Fujiwara
A 6000-year history of relative sea-level change on the western Nobi plain, at the footwall side of the Yoro fault, was reconstructed from three drilling cores based on analyses of sedimentary facies, grain-size distributions and electrical conductivity (EC), as well as 20 14C age determination. The Yoro fault comprises the northern part of the Yoro fault system. These cores show a prograding delta sequence. Two intervals characterized by fine deposits, mainly composed of fine sand, and high EC value are identified in sandy delta front deposits showing a general coarsening upward sequence. In synchronous with these changes in the delta front, a rapid rise of EC value is recognized in the abandoned channel fill deposits on the delta plain. These data suggest that temporal sea-level rise events occurred during the progradation process of the delta system. A probable cause of these events is coseismic subsidence. These subsidence events are dated at around 5600-4700 cal BP and 4600-3800 cal BP, respectively. The above-mentioned subsidence events broadly correspond with previously known faulting events at the Kuwana fault to the south of the Yoro fault. Evidence for the faulting of the Yoro and Kuwana faults associated with two historical earthquakes (AD 745 and AD 1586) accompanied by coseismic subsidence and synchronicity of the subsidence events identified in this study and faulting events at the Kuwana faults suggest that subsidence events identified in this study are caused by faulting at the Yoro fault. These results are consistent with the notion that the Yoro and Kuwana faults comprise a behavioral segment in the Yoro fault system.
基于沉积相、粒度分布和电导率(EC)分析，以及2014c年龄测定，研究人员利用三个钻孔岩心重建了位于Yoro断层下盘的Nobi平原西部6000年的相对海平面变化历史。约罗断裂是约罗断裂系统的北部。这些岩心呈递进的三角洲层序。在砂质三角洲前缘沉积中发现了以细砂为主的细沉积和高EC值的两个层段，显示出普遍的向上粗化序列。与三角洲前缘的变化同步，三角洲平原上废弃河道充填体的EC值也迅速上升。这些资料表明，时间海平面上升事件发生在三角洲系统的进积过程中。这些事件的一个可能原因是同震沉降。这些沉降事件的年代分别为5600 ~ 4700 cal BP和4600 ~ 3800 cal BP。上述沉降事件与先前已知的约罗断裂带以南Kuwana断裂带的断裂事件大致对应。Yoro断裂和Kuwana断裂的断裂与两次历史地震(公元745年和公元1586年)相关，并伴有同震沉降，以及研究中发现的沉降事件与Kuwana断裂事件的同向性表明，研究中发现的沉降事件是由Yoro断裂断裂引起的。这些结果与Yoro断裂和Kuwana断裂在Yoro断裂系统中构成一个行为段的观点相一致。
{"title":"Holocene Activity of the Yoro Fault System, Western Margin of the Nobi Plain, Central Japan, Detected by Rapid Relative Sea-level Rise Recorded in 20m-long Drilling Cores","authors":"Y. Niwa, T. Sugai, T. Ogami, Masayoshi Tajikara, K. Yasue, O. Fujiwara","doi":"10.5026/JGEOGRAPHY.119.668","DOIUrl":"https://doi.org/10.5026/JGEOGRAPHY.119.668","url":null,"abstract":"A 6000-year history of relative sea-level change on the western Nobi plain, at the footwall side of the Yoro fault, was reconstructed from three drilling cores based on analyses of sedimentary facies, grain-size distributions and electrical conductivity (EC), as well as 20 14C age determination. The Yoro fault comprises the northern part of the Yoro fault system. These cores show a prograding delta sequence. Two intervals characterized by fine deposits, mainly composed of fine sand, and high EC value are identified in sandy delta front deposits showing a general coarsening upward sequence. In synchronous with these changes in the delta front, a rapid rise of EC value is recognized in the abandoned channel fill deposits on the delta plain. These data suggest that temporal sea-level rise events occurred during the progradation process of the delta system. A probable cause of these events is coseismic subsidence. These subsidence events are dated at around 5600-4700 cal BP and 4600-3800 cal BP, respectively. The above-mentioned subsidence events broadly correspond with previously known faulting events at the Kuwana fault to the south of the Yoro fault. Evidence for the faulting of the Yoro and Kuwana faults associated with two historical earthquakes (AD 745 and AD 1586) accompanied by coseismic subsidence and synchronicity of the subsidence events identified in this study and faulting events at the Kuwana faults suggest that subsidence events identified in this study are caused by faulting at the Yoro fault. These results are consistent with the notion that the Yoro and Kuwana faults comprise a behavioral segment in the Yoro fault system.","PeriodicalId":356213,"journal":{"name":"Chigaku Zasshi (jounal of Geography)","volume":"137 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132499074","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 : 1900-01-01DOI: 10.5026/JGEOGRAPHY.117.870
Y. Kariya, Yutaka Matsunaga, Yosuke Miyazawa, J. Komori, M. Ishii, G. Sato
The Daisekkei Valley (1600-2300 m ASL) is a late Pleistocene glaciated trough in the northern Japanese Alps, and its attractive landscape has enchanted many climbers. Even today, there is a late-lying snowpatch 2 km long at the bottom of the valley in midsummer. Unique natural conditions in and around the Daisekkei Valley (e.g., Quaternary rapid uplift, complex geology, humid climates, sparse vegetation cover) have been responsible for the occurrence of various geomorphic changes that threaten climbers. This study, using an image data-logger capable of capturing a JPG image with a fixed time-interval in the summer of 2007 reveals supranival debris movements, micro-weather conditions and the behavior of climbers in the Daisekkei Valley. Analysis of captured images indicates that the daily numbers of dangerous supranival debris movements gradually decreased from early June to early August and supranival debris movements were caused by rock fragments moving in from valley walls or tributaries to the snowpatch, as well as posture changes of rock fragments on the snow surface with rapid ablation. Besides, image-inspection allows us to consider the relationships among climber traffic, micro-weather, and holiday almanac. Using an image data-logger for monitoring geomorphic changes is considered to be effective for analyzing alpine environments.
{"title":"Monitoring Rockfall and Supranival Debris Movement in the Shirouma Daisekkei Valley, Northern Japanese Alps","authors":"Y. Kariya, Yutaka Matsunaga, Yosuke Miyazawa, J. Komori, M. Ishii, G. Sato","doi":"10.5026/JGEOGRAPHY.117.870","DOIUrl":"https://doi.org/10.5026/JGEOGRAPHY.117.870","url":null,"abstract":"The Daisekkei Valley (1600-2300 m ASL) is a late Pleistocene glaciated trough in the northern Japanese Alps, and its attractive landscape has enchanted many climbers. Even today, there is a late-lying snowpatch 2 km long at the bottom of the valley in midsummer. Unique natural conditions in and around the Daisekkei Valley (e.g., Quaternary rapid uplift, complex geology, humid climates, sparse vegetation cover) have been responsible for the occurrence of various geomorphic changes that threaten climbers. This study, using an image data-logger capable of capturing a JPG image with a fixed time-interval in the summer of 2007 reveals supranival debris movements, micro-weather conditions and the behavior of climbers in the Daisekkei Valley. Analysis of captured images indicates that the daily numbers of dangerous supranival debris movements gradually decreased from early June to early August and supranival debris movements were caused by rock fragments moving in from valley walls or tributaries to the snowpatch, as well as posture changes of rock fragments on the snow surface with rapid ablation. Besides, image-inspection allows us to consider the relationships among climber traffic, micro-weather, and holiday almanac. Using an image data-logger for monitoring geomorphic changes is considered to be effective for analyzing alpine environments.","PeriodicalId":356213,"journal":{"name":"Chigaku Zasshi (jounal of Geography)","volume":"52 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130123087","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 : 1900-01-01DOI: 10.5026/JGEOGRAPHY.117.797
T. Tosha, N. Todaka, S. Makino, Hiroshi A Takahashi
Environmental assessments and safety control during and after CO2 injection are essential for CO2 geological storage, and we are required to evaluate long-term environmental changes and safety. However, long-term changes are difficult to detect directly because the leakage of CO2 is expected to be small and the evaluation is, sometimes, requested to cover more than 1,000 years. To solve this problem, a natural-analogue study, which inquires into environmental changes at present through a comparison with past geological phenomena, is one possible approach. When the Matsushiro earthquake swarm began in 1965, a large volume of subsurface water accompanied by CO2 gas was discharged along fracture zones. A natural-analogue study on the CO2 discharge during the earthquake swarm should be helpful to create a scenario of leakage and a guideline for the safety of CO2 geological storage. Surveys of the CO2 content in soil gas and CO2 flux emissions from the surface were carried out with carbon isotope ratio measurements to understand the current state at Matsushiro, and to make a conceptual model for environmental assessments and safety control. From geological and geophysical points of view, it is said that deep water gushing out from the surface caused the swarm of earthquakes. As this deep water is still gushing out, we planned to measure CO2 concentrations in soil gas and CO2 flux to examine present CO2 activities at Matsushiro. Because CO2 in the soil is also produced by activities of microbes, however, we decided to measure the isotope ratio of the carbon to distinguish CO2 in deep groundwater origin from that produced by microbes. We selected five survey lines and three survey areas based on previous geochemical measurements and fissure distribution during the earthquake swarm, and measured CO2 concentration in soil, CO2 flux, and isotope ratio. Although there were survey points on the thick fan deposit where CO2 concentration in the soil and CO2 flux were high, the isotope ratio indicated that the carbon is produced by the activity of microbes. On the other hand, the isotope ratio of the samples collected from the thin fan deposit area shows deep subsurface water as the origin. An investigation well was drilled into the basement. Subsurface water samples were collected near the bottom of the well in the igneous rock formation. Geochemical analyses and carbon isotope ratio measurements show higher concentrations of chloride and abiogenic CO2, indicating that groundwater of a deep origin with CO2 is still rising. We are now making a conceptual model of hydrogeological history at the next step. This natural analogue study of CO2 seepage could indicate the importance of understanding shallow hydrogeological characteristics in a CO2 storage field.
{"title":"Natural Analogue Study on CO2 Geological Storage: An Example of the Geochemical Survey at Matsushiro, Central Japan","authors":"T. Tosha, N. Todaka, S. Makino, Hiroshi A Takahashi","doi":"10.5026/JGEOGRAPHY.117.797","DOIUrl":"https://doi.org/10.5026/JGEOGRAPHY.117.797","url":null,"abstract":"Environmental assessments and safety control during and after CO2 injection are essential for CO2 geological storage, and we are required to evaluate long-term environmental changes and safety. However, long-term changes are difficult to detect directly because the leakage of CO2 is expected to be small and the evaluation is, sometimes, requested to cover more than 1,000 years. To solve this problem, a natural-analogue study, which inquires into environmental changes at present through a comparison with past geological phenomena, is one possible approach. When the Matsushiro earthquake swarm began in 1965, a large volume of subsurface water accompanied by CO2 gas was discharged along fracture zones. A natural-analogue study on the CO2 discharge during the earthquake swarm should be helpful to create a scenario of leakage and a guideline for the safety of CO2 geological storage. Surveys of the CO2 content in soil gas and CO2 flux emissions from the surface were carried out with carbon isotope ratio measurements to understand the current state at Matsushiro, and to make a conceptual model for environmental assessments and safety control. From geological and geophysical points of view, it is said that deep water gushing out from the surface caused the swarm of earthquakes. As this deep water is still gushing out, we planned to measure CO2 concentrations in soil gas and CO2 flux to examine present CO2 activities at Matsushiro. Because CO2 in the soil is also produced by activities of microbes, however, we decided to measure the isotope ratio of the carbon to distinguish CO2 in deep groundwater origin from that produced by microbes. We selected five survey lines and three survey areas based on previous geochemical measurements and fissure distribution during the earthquake swarm, and measured CO2 concentration in soil, CO2 flux, and isotope ratio. Although there were survey points on the thick fan deposit where CO2 concentration in the soil and CO2 flux were high, the isotope ratio indicated that the carbon is produced by the activity of microbes. On the other hand, the isotope ratio of the samples collected from the thin fan deposit area shows deep subsurface water as the origin. An investigation well was drilled into the basement. Subsurface water samples were collected near the bottom of the well in the igneous rock formation. Geochemical analyses and carbon isotope ratio measurements show higher concentrations of chloride and abiogenic CO2, indicating that groundwater of a deep origin with CO2 is still rising. We are now making a conceptual model of hydrogeological history at the next step. This natural analogue study of CO2 seepage could indicate the importance of understanding shallow hydrogeological characteristics in a CO2 storage field.","PeriodicalId":356213,"journal":{"name":"Chigaku Zasshi (jounal of Geography)","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134035500","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 : 1900-01-01DOI: 10.5026/JGEOGRAPHY.117.568
Yuichiro Nishimura, Kohei Okamoto, S. Boulidam
Many time-allocation studies have adopted questionnaires (activity diaries) or direct observation of informants. However, it is difficult to use questionnaires in rural areas of developing countries due to problems such as illiteracy, the fact that few people possess a watch, and the lack of place names in many rural and wild areas. Direct observation also has limitations because it is not possible to obtain information from many informants simultaneously. We developed a new survey method combining interviews with the use of GPS and GIS. The procedures are as follows. (1) Each informant is asked to carry a wristband GPS receiver for an entire day. The GPS unit records information related to the spatio-temporal aspects of the informant's activities. (2) After 24 hours of GPS, recording is completed; then the data are stored and represented visually using GIS software (ArcView 9.1). The investigator works out the shape of the spatio-temporal path of each informant by mapping tracking points with time information. (3) Subsequently, as GPS data reveals almost nothing about the content of activities, the investigator interviews each informant to clarify details of activities: what activity was carried out, at what time, where, and with whom. We conducted the survey in Dongkhuwaai Village, which is located about 30km from Vientiane, the capital of Laos. The daily activities of villagers consist mainly of a combination of subsistence agriculture, fishing, hunting, and gathering. By carrying out this survey, in which 138 villagers participated, it was verified that the new survey method has the following merits. (1) Using GPS improves the accuracy of spatio-temporal data. (2) GPS data can be easily correlated with satellite images and map data, which enables us to consider people's daily activities in combination with various geographical phenomena. (3) Investigators can obtain information outlining an informant's activities from GPS data before conducting interviews, thereby improving the efficiency of interviews.
{"title":"Daily Activity Survey in Lao Suburban Village Using GPS and GIS","authors":"Yuichiro Nishimura, Kohei Okamoto, S. Boulidam","doi":"10.5026/JGEOGRAPHY.117.568","DOIUrl":"https://doi.org/10.5026/JGEOGRAPHY.117.568","url":null,"abstract":"Many time-allocation studies have adopted questionnaires (activity diaries) or direct observation of informants. However, it is difficult to use questionnaires in rural areas of developing countries due to problems such as illiteracy, the fact that few people possess a watch, and the lack of place names in many rural and wild areas. Direct observation also has limitations because it is not possible to obtain information from many informants simultaneously. We developed a new survey method combining interviews with the use of GPS and GIS. The procedures are as follows. (1) Each informant is asked to carry a wristband GPS receiver for an entire day. The GPS unit records information related to the spatio-temporal aspects of the informant's activities. (2) After 24 hours of GPS, recording is completed; then the data are stored and represented visually using GIS software (ArcView 9.1). The investigator works out the shape of the spatio-temporal path of each informant by mapping tracking points with time information. (3) Subsequently, as GPS data reveals almost nothing about the content of activities, the investigator interviews each informant to clarify details of activities: what activity was carried out, at what time, where, and with whom. We conducted the survey in Dongkhuwaai Village, which is located about 30km from Vientiane, the capital of Laos. The daily activities of villagers consist mainly of a combination of subsistence agriculture, fishing, hunting, and gathering. By carrying out this survey, in which 138 villagers participated, it was verified that the new survey method has the following merits. (1) Using GPS improves the accuracy of spatio-temporal data. (2) GPS data can be easily correlated with satellite images and map data, which enables us to consider people's daily activities in combination with various geographical phenomena. (3) Investigators can obtain information outlining an informant's activities from GPS data before conducting interviews, thereby improving the efficiency of interviews.","PeriodicalId":356213,"journal":{"name":"Chigaku Zasshi (jounal of Geography)","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134387477","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}
Climate model experiments are carried out to understand the relationship between large-scale topography and climate variation. Mountain uplift experiments show that sea surface temperature, surface wind fields, precipitation and sea surface salinity are strongly influenced by mountain uplift. An enhanced Asian monsoon due to mountain uplift causes stronger seasonal coastal upwelling in the Indian Ocean and freshening in the Bay of Bengal, Yellow Sea and East China Sea. Mountain uplift experiments using a higher resolution atmospheric general circulation model reveal that the spatial pattern of precipitation becomes finer as resolution increases, and that there is a sharper contrast in the salinity distribution near coastal regions. Experiments in which the Panamanian Gateway is closed, opened and re-closed suggest that reorganization of the ocean current due to closure of the Panamanian Gateway induces a cooler and drier climate with a permanent halocline and sea ice in the subarctic Pacific.
{"title":"Evolution of Large Scale Topography and Variation in Climate","authors":"Motoi Tatsuo, Kitoh Akio, Midorikawa Takashi, Arakawa Osamu, Sasai Yoshikazu, Chan Wing-le","doi":"10.5026/JGEOGRAPHY.117.1015","DOIUrl":"https://doi.org/10.5026/JGEOGRAPHY.117.1015","url":null,"abstract":"Climate model experiments are carried out to understand the relationship between large-scale topography and climate variation. Mountain uplift experiments show that sea surface temperature, surface wind fields, precipitation and sea surface salinity are strongly influenced by mountain uplift. An enhanced Asian monsoon due to mountain uplift causes stronger seasonal coastal upwelling in the Indian Ocean and freshening in the Bay of Bengal, Yellow Sea and East China Sea. Mountain uplift experiments using a higher resolution atmospheric general circulation model reveal that the spatial pattern of precipitation becomes finer as resolution increases, and that there is a sharper contrast in the salinity distribution near coastal regions. Experiments in which the Panamanian Gateway is closed, opened and re-closed suggest that reorganization of the ocean current due to closure of the Panamanian Gateway induces a cooler and drier climate with a permanent halocline and sea ice in the subarctic Pacific.","PeriodicalId":356213,"journal":{"name":"Chigaku Zasshi (jounal of Geography)","volume":"201 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132600437","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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