Chigaku Zasshi (jounal of Geography)最新文献

{"title":"Relation between Land Use and River Water Quality of the Tama River Watershed","authors":"S. Kimura, M. Okazaki","doi":"10.5026/JGEOGRAPHY.117.553","DOIUrl":"https://doi.org/10.5026/JGEOGRAPHY.117.553","url":null,"abstract":"To optimize the reactive nitrogen cycle in an ecosystem, technologies to increase nitrogen use efficiency and reduce emissions of nitrogen must be developed. In a watershed-ecosystem, land uses with purification abilities can be a powerful tool to mitigate nitrogen loads from nonpoint sources. This study analyzes the influence of land use on nitrate concentration in the watershed of the Tama River, a typical urban river in Japan. The upstream area is occupied by forest, while the downstream area is dominated by urban land use. In the Tama River watershed, 59% of the total land use is forest ; 23% is urban area ; and, only 5% is occupied by agricultural land. Urban areas are distributed downstream from the middle reaches. The average nitrate nitrogen (NO3--N) concentration in 2004 increased from upstream to downstream: it was 0.7 mg N L-1 in the upstream area, while it rose to 6.0 mg NO3--N L-1 in the downstream area. The river water NO3--N concentration showed a positive correlation with the proportion of urban land use, while it showed a negative correlation with the proportion of forest. However, some small sub-watersheds have low values for NO3--N concentration despite highly urbanized land use. These sub-watersheds are characterized by higher proportions of paddy rice fields to the total area, ranging from 0.3 to 3.0%, and higher proportions of water body areas, ranging from 8.3 to 30.6%, compared to other sub-watersheds. This might indicate the purification ability of the water bodies and paddy rice fields. Land use within 0 to 50 m from the river water surface influenced water quality and forest and other water bodies reduced nitrate concentration. Construction of artificial wetlands or riparian forests would decrease the N load into the river.","PeriodicalId":356213,"journal":{"name":"Chigaku Zasshi (jounal of Geography)","volume":"28 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":"126185365","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}

{"title":"Development of “Historical Regional Statistics” and Utilization of the Data","authors":"Hiromasa Watanabe, Y. Murayama, K. Fujita","doi":"10.5026/JGEOGRAPHY.117.370","DOIUrl":"https://doi.org/10.5026/JGEOGRAPHY.117.370","url":null,"abstract":"Enormous amounts of statistics have been published since the start of the Japanese modern era. Among all of these statistics, modern statistics published in the Meiji era are fundamental for grasping the historical geography of Japan. GIS can be powerful analytical tool for applying such modern statistics to historical regional analyses. Although GIS has potential for historical regional analyses using modern Japanese statistics, studies are not making significant progress at the present time. A background factor is that municipal polygon data and digitized statistics in the Japanese modern era are not available to the public. As a result, in 2004, the authors established the open web-based database titled “Historical regional statistics,” which contains a variety of municipal polygon data and digitized statistics from the modern era. The purpose of this study is to review some digitized statistics and municipal polygon data contained in “Historical regional statistics,” and discus their availability through a case study. “Historical regional statistics” contains eight groups of statistics (39 statistics) and four groups of municipal maps (213 maps). Among these data, military statistics, “Meiji 24 Nen Chohatsu Bukken Ichiranhyo (Requisition Order List in 1891)”, “Fuken Tokei Hyo (Prefectural Statistics)” and “Consolidation of municipalities database” are available and provide versatility. The case study, which analyzes the regional structure of central Japan in the mid-Meiji era, applies the 1890 “Consolidation of municipalities database” and military statistics, “Meiji 24 nen Chohatsu Bukken Ichiranhyo (Requisition order list in 1891)”. Factor and cluster analyses are applied to explain the regional structure. In the factor analysis, eight factors are abstracted from 35 variables. Then, by applying the cluster analysis to the factor matrix, central Japan is classified into six regional types. Complicated research processes for handling or building of data are reduced by digitized statistics and municipal polygons. The regional structure analyzed in the case study can be understood from existing findings of historical geography in Japan. These points show the possible availability of “Historical regional statistics” for historical regional analyses with GIS. On the other hand, it is shown that data used in the case study contain some errors. This point is common to other data in “Historical regional statistics,” and needs to be corrected with the user's cooperation.","PeriodicalId":356213,"journal":{"name":"Chigaku Zasshi (jounal of Geography)","volume":"13 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":"128528457","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}

{"title":"Business Applications of Geographic Information Technology","authors":"H. Kohsaka, T. Sekine","doi":"10.5026/JGEOGRAPHY.117.455","DOIUrl":"https://doi.org/10.5026/JGEOGRAPHY.117.455","url":null,"abstract":"The aim of this paper is to review the present situation of business Geographic Information Systems （ GIS ） in Japan. This paper especially focuses on various geographic information services produced by geographic information technology. Geographic information is defined as attri-bute data with location and geographic information technology is considered in the second section in terms of software and hardware for manipulating geographic information. The third section reviews location-based services （ LBS ） , which trace positions in real-time using location sensor technology. LBS are classified into six types of service: provision of information specified for a position, tracing service for people, tracing service for vehicles and ships, tracing service for luggage and goods, proximity-based notification, and proximity-based actuation. Spatial analysis on GIS has been applied in business tools to assist sales promotion activities and the posting of handbills in shops and offices. The fourth section presents trade area analysis used to perform effective sales promotion activities. Rating methods and spatial interaction models are also used for location assessments of sites proposed for new shops. The fifth section considers geodemographics as an area marketing tool. The last section presents the outlook for business GIS in Japan.","PeriodicalId":356213,"journal":{"name":"Chigaku Zasshi (jounal of Geography)","volume":"34 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":"128601032","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}

{"title":"Chromitites: An Enigmatic Mantle Rock Type","authors":"S. Arai","doi":"10.5026/JGEOGRAPHY.119.392","DOIUrl":"https://doi.org/10.5026/JGEOGRAPHY.119.392","url":null,"abstract":"Various characteristics of podiform chromitites, an enigmatic mantle rock member, are reviewed in this article. Chromitites are composed of chromian spinel, with the general formula (Mg, Fe2+)(Cr, Al, Fe3+)2O4, and silicates (mainly olivine). The Fe3+ content is generally very low, being less than 0.1 to all trivalent cations, in mantle chromian spinels. The Mg/(Mg + Fe2+) ratio (= Mg#) changes inversely with the Cr/(Cr + Al) ratio (= Cr#), which increases with an increase of degree of partial melting of mantle peridotites. The Cr# of chromian spinel is generally higher than 0.4 (generally 0.6 to 0.8) in podiform chromitites, varying widely from 0.1 to 0.9 in the mantle peridotite. The podiform chromitite forms pod-like bodies (dimensions of up to 1.5 km × 150 m for an individual pod) with a dunite envelope, totally set within mantle harzburgite. In well-preserved ophiolites, they occur in the uppermost mantle, especially in and beneath the Moho transition zone, which is dominated by dunite. The Cr# of chromian spinel is relatively low (0.4 to 0.6) around the Moho transition zone, and high (>0.6) at deeper levels in the mantle section. Chromitites are denser and less anisotropic in Vp than peridotites, and the Vp is 8.5 to 9 km/sec depending on the proportion of chromian spinel, and higher in the former than in the latter.  The podiform chromitite has been interpreted to be one of melt/rock interaction products within the uppermost mantle harzburgite; hybridization of relatively Si-rich melt formed by the breakdown of orthopyroxenes of the wall harzburgite and subsequently supplied primitive melt cause oversaturation in chromian spinel, giving rise to formation of chromitite with a dunite envelope. The fractionated melt leaving high-Cr# podiform chromitite is possibly of arc-magma affinity. Chromitites with low-Cr# (0.4 to 0.6) chromian spinel can be in equilibrium with MORB. Recently found ultra-high pressure minerals, such as diamond, moissanite, Fe-silicides and Ni-Fe-Cr-C alloys, within chromian spinel of podiform chromitites make the genetical history of chromitites highly enigmatic. A new story, which incorporates the genesis and involvement of these highly reducing, ultra-high pressure minerals, is required.","PeriodicalId":356213,"journal":{"name":"Chigaku Zasshi (jounal of Geography)","volume":"33 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":"130068008","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}

{"title":"The Decline of the American Whaling Industry during the Industrial Revolution in the Latter Half of the 19th Century","authors":"A. Ôsaki","doi":"10.5026/JGEOGRAPHY.119.615","DOIUrl":"https://doi.org/10.5026/JGEOGRAPHY.119.615","url":null,"abstract":"This study examines the American whaling industry, which was based in New England and dominated most of the Western oil market in the 18th and 19th centuries. Previous studies by the author examined why the industry was attracted to this region, highlighting the favorable economic environment of the area, which allowed investors to accumulate the necessary funds to launch whaling ventures. Each investment consortium that provided funds to whaling vessels organized limited partnerships with individual vessels. This enabled consortiums to collect funds from a variety of stakeholders other than just businessmen involved in whaling and their families. Crewmembers of the vessel, reflecting the multi-racial society of the United States, were also free to select employers without relying on a conventional employer-employee relationship. Taken together, these factors led to New England attracting funds and labor from both within the region and further afield, and developing into the whaling center of the United States. An additional reason for New England's development as a whaling base was the global expansion of the industry to cover the Atlantic, Pacific, and Indian oceans, with only the Southern Ocean not affected by this growth. Crewmembers were also paid from a ship's profits using the lay system. This payment by piece ratio ensured a minimum payment to crewmembers while guaranteeing a return for investors. The hiring of native islanders as part-time laborers in the whalers' areas of operation also kept expenditure to a minimum, with all of these factors contributing to investors' profits. Against this background, the whaling industry prospered and profited up until the 1850s. In the 1870s, however, the industry started to decline as whale resources decreased and the price of whale oil fell as a result of increased petroleum production. This study examines the details of how whaling voyages were managed during this period and how New England's whaling industry underwent a rapid transformation into a mechanized cotton industry with the owners of whaling vessels switching their investments to the cotton industry at New Bedford, the center of the whaling industry in New England. The rapid change from industrial whaling to the mechanical cotton industry in New England was made possible with the abundant funds accumulated by the whaling industry. The reestablishment of consortiums progressed smoothly as limited partnerships already existed and the labor market adapted efficiently from supplying whaling vessels to supplying female workers for the cotton industry due to the presence of non-conventional employment rules. We can see, therefore, in this region the development from one industry to another was controlled only by market-based mechanisms of American management. This is in sharp contrast to the Japanese fishing industry, which developed from a manufacturing fishery through technological innovation and utilizing community manpower or industrial po","PeriodicalId":356213,"journal":{"name":"Chigaku Zasshi (jounal of Geography)","volume":"119 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":"130230167","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}

{"title":"Origin of Materials Erupting from Mud Volcano in Tokamachi City, Niigata Prefecture, Central Japan","authors":"Toshikazu Shinya, Kazuhiro Tanaka","doi":"10.5026/JGEOGRAPHY.118.340","DOIUrl":"https://doi.org/10.5026/JGEOGRAPHY.118.340","url":null,"abstract":"Mud volcanoes are structures formed as a result of the emissions on a land surface or the sea floor of argillaceous material, which is composed of erupting remobilized mud, petroliferous or magmatic gases, and high-salinity water. Recently, large constructions have been planned deep underground besed on the expectation of geological stability. Therefore, it is important to study the origin of erupted mud and groundwater and the depths from which they ascend when evaluating long-term stability. Three active mud volcanoes and a passive mud volcano are found in the Tertiary Shiiya Formation distributed in Tokamachi City, southern part of Niigata Prefecture. Detailed descriptions of the mud volcanoes are provided by Shinya and Tanaka (2005). However, the origin of erupted mud and the formation mechanism of abnormal pore water pressure have not yet been identified. The authors measured the oxygen and hydrogen isotopic ratio of groundwater and vitrinite reflectance of coal fragments separated from erupted mud of an active mud volcano to investigate the origin of erupted mud, particularly the depth of the origin, and the formation mechanism of abnormal pore water pressure. As a result, δ18O and δD values of erupted water are 1.2‰, -5‰ respectively, showing good agreement with those of the Nanatani Formation distributed at a depth of 3400 m in depth in the studied area. Vitrinite reflectance (Ro) shows a bimodal distribution (i.e., 0.3-1.2% and 1.5-1.8%). Ro value of coal fragments sampled from the Shiiya Formation at the outcrop in the studied area are 0.3-0.45%. High Ro (1.5-1.8%) values of coal fragments are obtained in core samples at a depth of 4000 m in the Gimyo SK-1 oil well, which was excavated 2 km NW from the mud volcano. As a result of an investigation of erupted materials at the mud volcano, they were found to have originated at depths of from 3400 m to 4000 m in the studied area. Geothermal temperature of underground at depth of 3400 m to 4000 m in the in the studied area is estimated to be about 120°C to 150°C. Estimated temperature is high enough to cause diagenetic transition from smectite to illite. Transition from smectite to illite results in the release of a large volume of pore water into the sediment. It is concluded that dehydration due to mineral transition might be the major reason for abnormal pore water pressure formation at depths of 3500 m to 4000 m in the study area.","PeriodicalId":356213,"journal":{"name":"Chigaku Zasshi (jounal of Geography)","volume":"29 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":"128870573","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}

{"title":"Reconstruction of Cosmic Ray Variations during Geomagnetic Events from Polar Ice Core Studies","authors":"T. Aze","doi":"10.5026/JGEOGRAPHY.119.527","DOIUrl":"https://doi.org/10.5026/JGEOGRAPHY.119.527","url":null,"abstract":"Cosmogenic Radio Nuclides (CRNs) are produced by nuclear reactions induced by cosmic rays in the Earth's atmosphere. The production rate of CRNs varies because changes in geomagnetic field intensity and solar activity strongly influence galactic cosmic rays, especially the lower part of energy. CRNs are produced in the upper atmosphere and are deposited on ice sheets in both Greenland and Antarctica, hence, ice cores in the polar regions provide excellent records of past histories of cosmic rays because of their continuous and relatively simple depositional processes. In recent studies, high-resolution records of 10Be flux from ice cores have been reported, and these revealed the continuity of 205-year solar cycles over the last glacial period. In particular, the changes induced in the production rate of CRNs by solar modulations increased during periods of low geomagnetic field intensity, such as the Laschamp geomagnetic excursion. The results obtained in this study suggest that it may be possible to obtain a better understanding of long-term solar activity through a high-resolution 36Cl analysis of the polar ice sheet.","PeriodicalId":356213,"journal":{"name":"Chigaku Zasshi (jounal of Geography)","volume":"23 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":"128926690","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}

{"title":"Climatic Variations in Relation to Large-scale Air-sea Interaction","authors":"R. Kawamura","doi":"10.5026/JGEOGRAPHY.117.1063","DOIUrl":"https://doi.org/10.5026/JGEOGRAPHY.117.1063","url":null,"abstract":"In the tropics, the El Nino-Southern Oscillation (ENSO) occupies a major part of the interannual air-sea interactive system. The ENSO plays a vital role in triggering the occurrence of extraordinary anomalous climates and weather not only in the tropics but also in the extratropical regions. In the South Asian monsoon region, the ENSO can influence the interannual variability of the monsoon system through at least two different impacts. During the decay phase of ENSO (from winter to summer) its delayed impact operates through large-scale air-sea interaction in the tropical Indian Ocean and land-surface hydrological processes over the Asian Continent, eventually bringing about change in summer monsoon activity in June and July. During the ENSO growth phase (from summer to winter), in contrast, its direct impact is considered to account for monsoon interannual variability especially in August and September. East Asian monsoon variability is also significantly affected by ENSO-related tropical forcing. Especially in early winter, ENSO-related anomalous convection can give rise to a change in the East Asian winter monsoon system through stationary Rossby wave propagation along the South Asian waveguide, but the remote response depends on the geographical configuration of the anomalous tropical convection. In summer, the ENSO's delayed impact is associated with excitation of an extratropical teleconnection, which causes anomalous weather in northeastern Asia. Midlatitude air-sea interactions and their potential impact on large-scale atmospheric circulations are also discussed. The coexistence of the East Asian winter monsoon flow and western boundary current makes air-sea heat exchanges in the Kuroshio extension very active. Due to enhanced baroclinicity and surface heat fluxes from the ocean, a number of extratropical cyclones tend to develop explosively in the vicinity of Japan. The activity of these extratropical cyclones contributes to the downstream development of upper-level teleconnections.","PeriodicalId":356213,"journal":{"name":"Chigaku Zasshi (jounal of Geography)","volume":"114 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":"116461012","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}

{"title":"The Structure of the International Air Network through the Social Network Analysis","authors":"Ho-sang Lee","doi":"10.5026/JGEOGRAPHY.117.985","DOIUrl":"https://doi.org/10.5026/JGEOGRAPHY.117.985","url":null,"abstract":"This study aimed at examining the structure of the international air network through the analysis of inter-city spatial interactions. For this purpose, this study applied a modified social network analysis model to examine spatial interactions between cities. The international networkability of cities and the connectivity of the international air routes were measured in the international air network in 1992 and 2004. The connection system between cities was analyzed, using air routes that show the maximum connectivity of each city. The connection system, composed of cities with high networkability in the global network, and the changes were also examined. As a result, the analysis of the nearest-neighbor distance between the cities revealed that in both 1992 and 2004, the center of the global network was formed around London through connections to Paris, New York, Amsterdam, and Frankfurt, and most of the cities in Europe and America were connected to London. The Asian cities, however, formed a different connection system around such cities as Tokyo, Singapore, and Hong Kong. In the connection system of the global network, the Asian cities showed dynamic changes in their connection patterns.","PeriodicalId":356213,"journal":{"name":"Chigaku Zasshi (jounal of Geography)","volume":"39 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":"128769797","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}

{"title":"Heat Flow Distribution around the Joetsu Gas Hydrate Field, Western Joetsu Basin, Eastern Margin of the Japan Sea","authors":"H. Machiyama, M. Kinoshita, R. Takeuchi, R. Matsumoto, M. Yamano, H. Hamamoto, M. Hiromatsu, M. Satoh, J. Komatsubara","doi":"10.5026/JGEOGRAPHY.118.986","DOIUrl":"https://doi.org/10.5026/JGEOGRAPHY.118.986","url":null,"abstract":"Methane seep activity around the Joetsu Gas Hydrate Field of the western Joetsu Basin, eastern margin of the Japan Sea, was investigated in detail using heat flow measurements. Heat flow was obtained by Ewing-type heat flow probe and SAHF probe with five thermistors at 11-cm intervals using a ROV during nine research cruises in 2004-2008. Average heat flow value obtained on a normal muddy seafloor in this area is 98 ± 13 mW/m2, which is consistent with the ambient heat flow in the Japan Sea. Based on the results of three day's monitoring, temperature fluctuations (> 0.02 K) of bottom water influence sub-bottom temperature at around a depth of 20 cm. Heat flow values greater than 300 mW/m2 were measured not only at the methane venting sites but also in the some areas covered by bacterial mats. This high heat flow value (> 150 mW/m2) is confined to certain areas (several meters to a few tens of meters scale) on the mounds in the Umitaka Spur and the Joetsu Knoll. Therefore, methane migration from the deep subsurface to seafloor occurs on a very local scale, although seismic profiles show the presence of many small faults through gas chimneys just below the mounds. Convex temperature profiles around the gas venting sites indicate the presence of fluid discharges with Darcy's flow velocity of 1.3 × 10-6 m/s and 5.0∼8.6 × 10-7 m/s, respectively. On the other hand, concave temperature profiles, obtained in the “collapsed hydrate zone” on the mounds, may indicate the presence of a recharge zone. Some temperature reversal profiles in areas covered by bacterial mats were probably caused by a lateral fluid movement from a fluid conduit or by the presence of a methane fluid pool. Some apparent negative geothermal gradient anomalies were obtained only in the “collapsed hydrate zone”. Most of these apparent negative anomalies are possibly explained by the influence of bottom water temperature fluctuations. There seem to be some different hydrological regimes in the high methane flux area of the Joetsu Gas Hydrate Field.","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":"127494929","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}