著者

小原 一成

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.116, no.1, pp.114-132, 2007-02-25 (Released:2009-11-12)

参考文献数

60

被引用文献数

3 2

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Water affects many geological and geophysical phenomena, for example, earthquake generation. Recently, anomalous earthquakes, which are strongly related to fluid have been detected in a subduction zone by densely distributed geodetic and seismic observation networks. These are called slow earthquakes and are divided into many categories of earthquakes. The long-term slow slip in Tokai or Bungo Channel, which occurs at the subducting plate interface, is a phenomenon with a very long time-constant ranging from months to years. At the deeper part of the long-term slow slip, the short-term slow slip occurs with a period of several days associated with the non-volcanic deep low-frequency tremor in the transition zone on the plate interface in southwest Japan. These slow earthquakes might be related to fluid liberated from the down-going slab by dehydration process. At the shallower part of the subducting plate interface, the very low-frequency earthquakes occur in the accretionary prism near the Nankai trough. These slow earthquakes indicate a weakening of frictional strength at the plate interface and low stress drop due to the existence of fluid.

著者

佐藤 友彦 吉屋 一美 丸山 茂徳

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.128, no.4, pp.571-596, 2019-08-25 (Released:2019-09-20)

参考文献数

109

被引用文献数

11 11

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Phylogenetic analysis is one of the useful tools available for revealing the evolution of life on the Earth; however, it has difficulty in principle distinguishing old and new genomes just by comparing phylogenomic trees. To overcome this difficulty, a new method is introduced which utilizes the Earth's history derived from geologic information to trace genomic evolution. This idea is inspired by Darwin's natural selection, and explains how living organisms change with the environment. In other words, life's genome does not change if the environment remains the same. A key is the birthplace of life on Hadean Earth, which is thought to be an ultra-reducing environment with H2 produced in abundance through serpentinization. OD1 is a potential microbe that has survived on the Earth since the Hadean. Its habitat, Hakuba-Happo in Japan, is a unique serpentinite-hosted hydrothermal system on land, and it has avoided evolution by remaining in a super-reducing environment from the Hadean to the present. OD1 is regarded as a “living fossil” of the Hadean microbe. Ultra-reducing environments have disappeared over the Earth's history. How has OD1 survived since the Hadean to the present? A possible scenario is proposed based on Plate Tectonics. OD1 habitats have gone through the following transitions: (1) super-reducing environment in a natural nuclear geyser on a primordial continent in the Hadean; (2) serpentinite-hosted hydrothermal system along a mid-oceanic ridge transform fault during the Archean-Proterozoic; (3) subduction-accretion and escape from oxygenated Phanerozoic ocean floor; and, (4) jacked up by growth of accretionary complexes and taking refuge in a hydrothermal system above a volcanic front. OD1 habitats have been reduced with geological age as free oxygen has increased in the surface environment. OD1 may be a “living microfossil” of the Hadean, making its way continuously through ultra-reducing environments on a tightrope.

著者

田村 芳彦

出版者

Tokyo Geographical Society

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.112, no.5, pp.781-793, 2003-10-25 (Released:2009-11-12)

参考文献数

25

被引用文献数

1 1

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Mantle melting and production of magmas in NE Japan may be controlled by locally developed hot regions within the mantle wedge that form inclined, 50 km-wide fingers. In this case, are these hot fingers chemically and/or isotopically different from the host mantle wedge? Forty-four Quaternary volcanoes in NE Japan have been reviewed to evaluate twodimensional strontium isotopic variations, and to infer 87Sr/86Sr contours of the source mantle. The isotopic composition of magma source materials at depth is found to have little relationship with slab depth, suggesting that mantle heterogeneity was established before the flux of fluid released from the subducting slab reached the magma source regions. On the other hand, Miocene Japan Sea back-arc Yamato basin basalts have the same isotopic variation as the Quaternary volcanic arc. Cousens et al. (1994) suggested the possibility that partial melts of sediments, forming at a depth of >200 km may mix with mantle wedge material (87Sr/86Sr0.703), resulting in a magma source component with enriched 87Sr/86Sr of0.705. I suggest that after the cessation of Yamato basin rifting, a MORB-like mantle source (87Sr/86Sr0.703) in the mantle wedge below the Quaternary NE Japan arc was replenished by a fertile mantle material (87Sr/86Sr0.705) through convection induced by the subducting lithosphere. On its way to the shallower mantle wedge (<150 km), the fertile mantle material changes shape from a hot sheet to hot fingers, for reasons not yet fully understood. Thus, the hot fingers, with 87Sr/86Sr of0.705, extend from150 km below the back-arc region towards the shallower mantle (50 km) beneath the volcanic front. A conveyor-like return flow is interpreted to carry the remnants of these fingers to depth, resulting in greater amounts of fertile material being incorporated in diapirs beneath the volcanic front, and smaller amounts incorporated in areas behind the front.

著者

浜田 信生

出版者

Tokyo Geographical Society

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.110, no.2, pp.132-144, 2001-04-25 (Released:2009-11-12)

参考文献数

20

被引用文献数

5 4

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Based on macro seismic and instrumental observation data covering a period of over hundred years, the characteristics of seismic activity around Miyakejima, Kozushima, and Niijima, the northern Izu islands, were investigated. Seismic activity is distributed along the Zenisu ridge and the Nishi-Shitito ridge to the west and along Niijima, Miyakejima, Mikurajima and Hachijojima islands to the east. Most of the seismic activity in the region is of the swarm type and is often induced by a large earthquake or magmatic activity at Miyakejima and other volcanoes. Comparison of macro-seismic data of large earthquakes in the late 1800s and the early 1900s with a seismic intensity map of recent earthquakes suggested that the maximum size of an earthquake in the region is around a magnitude of 6.5 on the JMA magnitude scale. Linear arrangements of seismicity in the NE-SW direction, which is parallel with the Zenisu ridge, and in the NW-SE direction, which is almost normal to the former and parallel to the direction of the plate motion of the Philippine Sea plate, are often recognized. While the strike slip-type earthquake with a NE-SW tension axis is predominant in the region along Niijima, Miyakejima, Mikurajima, and Hachijojima islands, a strike slip with E-W tension axis is predominant in the region along the Zenisu ridge and the Nishi-Shitito ridge. A complex tectonic setting of the region, back arc spreading, collision of the Philippine Sea plate to the Eurasian plate around the Izu peninsula, deformation of the plate due to the subduction of slab from the Suruga and the Sagami trough, must shape the characteristics of seismic activity in the region such as the upper limit of earthquake scale, swarm-type activity, close relation with volcanic activity, and regional stress pattern.

著者

藏田 延男

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.60, no.4, pp.183-190, 1951-12-30 (Released:2009-11-12)

参考文献数

13

被引用文献数

1

著者

都城 秋穂

出版者

Tokyo Geographical Society

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.99, no.3, pp.217-229, 1990-06-25 (Released:2009-11-12)

参考文献数

10

被引用文献数

1 1

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The chemical compositions of solid-solution minerals in metamorphic rocks are controlled by equilibria not only of exchange reactions but also of net-transfer reactions among coexisting minerals. In rocks with a variance of 2, the compositions of solid-solution minerals are functions of temperature and pressure alone as is illustrated in Figs. 2 and 3, and so can be used as a measure of the P-T condition under which the rocks were recrystallized. In rocks with a variance of 3 or greater, on the other hand, the compositions of solid-solution minerals vary not only with temperature and pressure but also with the bulk-rock composition (Fig. 4). The growth of zoned crystals causes fractional crystallization, resulting in a change of composition of the reacting system. If the variance of the system is 3 or greater, the change of the composition of the reacting system causes a change in the composition of the crystallizing mineral.Pelitic metamorphic rocks are commonly simplified as belonging to the 6-component system : Al2O3-FeO-MgO-K2O-SiO2-H2O. In this case the mineral assemblages may be shown on the THOMPSON AFM diagram. Any 3-AFM phase assemblage in the diagram has a variance of 2, whereas any 2-AFM phase assemblage has a variance of 3.In the paragenetic relations of garnet, MnO commonly plays an essential role, and so garnet-bearing metapelites are commonly treated as belonging to the 7-component system : Al2O3-FeO-MgO-MnO-K2O-SiO2-H2O. Most metapelites with MnO-rich garnet have a variance of 3 or greater. Garnets in low- and middle-grade metamorphic rocks are usually strongly zoned. Hence, the composition (or the MnO content) of garnet is strongly influenced by the initial bulk-rock composition and fractional crystallization. SPEAR (1988) has calculated the progressive compositional change of garnet that grows not only under complete equilibrium condition but also with fractional crystallization for garnet-bearing 3-AFM phase assemblages that are observed in the Barrovian sequence.In the Sanbagawa high P/T ratio metamorphic belt, progressive metamorphism is represented by a sequence of the chlorite zone, garnet zone (with no biotite), and biotite zone (with garnet) for metapelites. In other words, garnet begins to occur at a considerably lower temperature than biotite. In the garnet zone, garnet probably forms by reaction involving Tschermak exchange component like (4), whereas in the biotite zone, garnet forms by the same reactions as in the garnet zone of the Barrovian sequence. Such a change in the garnet-producing reactions between the two zones may cause a break in the MnO and FeO curves in the composition profile of zoned garnets. Some of the observed features of the compositional trends of garnets could be ascribed to the effect of a variation in bulk-rock composition.The average composition of zoned garnets in metapelite shows a progressive decrease of the MnO content with increasing metamorphic grade. This is probably related mainly to a progressive increase of the amount of garnet. Higher pressure tends to increase the amount of garnet, and to decrease its MnO content.

著者

山田 直利 矢島 道子

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.120, no.4, pp.692-704, 2011-08-25 (Released:2011-11-10)

参考文献数

21

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Edmund Naumann (1854–1927) came from Germany and stayed in Japan for ten years from 1875. He performed a lot of pioneering research on the geology and geography of Japan, which were written mostly in German and recently translated into Japanese by N. Yamashita (1996). However, a paper titled “Skizze der Orographie von Japan” published in 1893 on “Petermanns Geographische Mitteilungen” as the third article of Naumann's “Neue Beiträge zur Geologie und Geographie Japans” has not yet been translated. The paper, which we have now translated into Japanese as “Nihon Sangaku Shi Taiyo”, consists of two parts. The first part deals with the relationship between the topography of mountainous lands and geology, in terms of volcanoes, old mountainlands, granitic mountains, coastlines, depressions, longitudinal and transverse valleys, watersheds, etc. The second part deals with the topographic character of each geotectonic zone of Japan: the northern and the southern wings of the Japan Arc and the Fossa Magna intervening between both wings. One figure and one table are included in this paper. Fig. 1 is an altitude layer map of the main three islands of Japan with a scale of 1:2,600,000, the earliest one drawn with contour lines. Table 1 is a list of the main mountaintops of Japan (eighty-seven mountains), including location, altitude, and geologic nature. Furthermore, a supplementary figure, which shows the distribution of the main mountaintops, watersheds, and geotectonic divisions of Japan, was made by the translators.

著者

岩橋 純子 安藤 明伸 西岡 芳晴 川畑 大作 白石 喬久

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.131, no.4, pp.463-472, 2022-08-25 (Released:2022-09-08)

参考文献数

19

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A system was created using an exploration-type computer game as the basic material, and its educational effects were verified with the aim of stimulating the interest of students of the digital native generation in the local history of the region. Research classes were conducted using Minecraft (Mojang/Microsoft) teaching materials at Miyagi University of Education Junior High School in Sendai City. The theme of the classes was to convey knowledge about the geology and geological history of the region. Teaching materials were created for students to learn about geological formations in the Kamisugi area of Sendai City, including the region of their junior high school, with the aim of deepening their interest in local geological history and their understanding of the changing earth. A Minecraft world was used with underground strata that reflected information from a geological boring survey conducted in the past at the school, school buildings, and teleportable landscapes of past geological eras, and questions were asked on knowledge of geology based on school textbooks or research papers. The following were confirmed from the research classes at the junior high school. The game using a familiar school as a setting was very popular among the students, and they were not bored by the knowledge questions. The key words of the geological era that the students reached were frequently mentioned in the questionnaire given after the classes. The game is considered to be effective for helping students to understand and remember things visually, while having an enjoyable and positive experience.

著者

苅谷 愛彦 原山 智 松四 雄騎 清水 勇介 松崎 浩之

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.131, no.4, pp.447-462, 2022-08-25 (Released:2022-09-08)

参考文献数

59

被引用文献数

1

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The geomorphological and geological characteristics, distributions, and ages of block slopes that developed at two alluvial cones (Bentenzawa valley and Okumatazirodani valley) along the Azusa River in the Kamikochi area, northern Japanese Alps, are clarified. These block slopes were believed to be of Pleistocene glacial origin in previous studies. A field survey was conducted, applying microtremor array observations to estimate subsurface geology, and in situ terrestrial cosmogenic nuclide (TCN) dating to estimate age of occurrence. At the Bentenzawa alluvial cone, the block slope is composed of large blocks and lithic fragments originating from heterogeneous igneous rocks, mainly of welded tuff and granophyre, that do not exist in the Bentenzawa valley watershed. Large blocks and lithic fragments of the block slope show clast-supported facies accompanied by jigsaw-crack fracture structures without a fine matrix. A mass of rock blocks fell from a steep wall of igneous rocks around the head of the Okumatajirodani valley, at approximately 2280 to 3090 m a.s.l., on the opposite side of the Bentenzawa valley. Rock slope failure and runout debris flow of blocks are thought to be the principal motions behind the mass movement from the rockwall. Block behavior comprised 3 km horizontal and 1.5 km vertical movements. Blocks were finally transported to the alluvial cone of the Bentenzawa valley to form an opposing impact slope. The results of microtremor array observations suggest that materials of rock blocks about 20 m thick spread and were buried beneath the present riverbed of the Azusa River. The estimated volume of landslide materials is more than 1.1 × 107 m3; age is estimated to be 6900 ± 1000 yrs BP. The Bentennzawa block slope is not of glacial origin. The block slope at the Okumatajirodani alluvial cone consists of large lithic fragments of igneous rocks distributed in this watershed. A mass of rock blocks was supplied by slope failure or debris flow in the Okumatajirodani valley, and was transported and emplaced on the alluvial cone. The volume of the failure is estimated to exceed 2.9 × 105 m3 and its age is estimated to be 900 ± 100 yrs BP.

著者

吉屋 一美 佐藤 友彦 大森 聡一 丸山 茂徳

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.128, no.4, pp.625-647, 2019-08-25 (Released:2019-09-20)

参考文献数

77

被引用文献数

4 4

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The Hadean surface was mainly covered by three kinds of rock: komatiite, KREEP basalt, and anorthosite, which were remarkably different from those on the modern Earth. Water–rock interactions between these rocks and water provided a highly reducing environment and formed secondary minerals on the rock surface that are important for producing metallo-enzymes for the emergence of primordial life. Previous studies suggest a correlation with active sites of metallo-enzymes and sulfide minerals based on an affinity with their structure, but they do not discuss the origins of metallic elements contained in these minerals, which are critical to understand where primordial life was born. Secondary minerals formed through water–rock interactions of komatiite in a nuclear geyser system are investigated, followed by a discussion of the relationship between active sites of metallo-enzymes and secondary minerals. Instead of komatiite, we used serpentinite collected from Hakuba Happo area, Nagano Prefecture in central-north Japan, which is thought to be one of the Hadean modern analogues for the birthplace of life. Several minor minerals were found, including magnetite, chromite, pyrite, and pentlandite, in addition to the major serpentine minerals. Pentlandite is not been mentioned in previous studies as a candidate for supplying important metallic elements to form metallo-enzymes in previous studies. It also acts as a catalyst for hydrogen generation, because it closely resembles the structural features of an active site of hydrogenases. Nickel-iron sulfide, pentlandite, is considered to be one of the important minerals for the origin of life. In addition, what kinds of minor mineral would be obtained from water–rock interactions of these rocks is estimated using a thermo-dynamic calculation. KREEP basalt contains large amounts of iron, and it could be useful for producing metallo-enzymes, especially for ferredoxins, an electron transfer enzymes associated with the emergence of primordial life.

著者

奥山 育子

出版者

Tokyo Geographical Society

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.95, no.1, pp.46-61, 1986-02-25 (Released:2009-11-12)

参考文献数

19

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Most of the Japanese Islands have experienced intensive rural exodus caused by the rapid economic growth since 1960s. The excellent papers on these migration processes have been published. Comparing with the migration processes since 1960s, those before the World War II had distinctive features in each island. Their studies have no sufficiently advanced because of the difficulties to follow the statistical data. This article aims to analyze the features of migration process in the Hachijou-jima (Hachijou Island) mainly from the beginning of the Meiji period to the World War II.The Hachjiou-jima has been historically known as a jail island. The exodus from the island was strictly prohibited in the Edo period, but the agricultural emigration to Mainland villages was allowed in 1777. The economic activities in the Hachijou-jima had based on the traditional sifting cultivation and the commercial production of Kihachi-jou (silky weaving), but the scarcity of economic resources and the agricultural low productivities had historically brought about the overpopulation. This economic structure had not been transformed in the Meiji period. But with the beginning of the colonization of Ogasawara Islands to develop the sugarcane industries, this island had experienced the intensive outmigration since 1890s. The migration process in this first stage has the characteristics as follows : (1) The emigrants were not from the peasants of lower classes. They kept the ownership of their agricultural lands and sometimes enlarged it by the purchase even after moving to Ogasawara Islands (Fig. 1 and 2).(2) They usually migrated with all family members and their family heads were from younger age-group (Table 3).(3) The migration flows to Tokyo or the neighbouring islands were not significant.The success stories of migrants in this first stage accelerated the spacial mobilities of islanders. The migrantion flows expanded to Hokkaido, Minamidaito-jima and the Japanese colonies such as Korea, Taiwan and their neighbouring islands. The economic acitivities in the Taisho period were mainly the dairy farming and charcoal making, but they severely suffered from the economic damages after the Great Depression. With the territorial expansion policy in this period, the migration flows of Hachijou islanders also expanded to Japanese colonies such as Mariana, Carolin and Marshall Islands. The features of migration process in the second stage were those as follows : (1) Migrants engaged in sugarcane industries as tenants.(2) They were from the peasants of lower classes.(3) Many of them had experienced the migration to Ogasawara or Minamidaito-jima Islands, or had the relatives in these islands (Fig. 3).These migration process came to the end with the opening of the World War II.

著者

香月 興太 瀬戸 浩二 菅沼 悠介 Dong Yoon YANG

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.128, no.3, pp.359-376, 2019-06-25 (Released:2019-07-11)

参考文献数

22

被引用文献数

3 5

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A suitable sampling tool is indispensable for making sediment observation. Eleven portable sediment core samplers using lake sediment observations are introduced: two box core samplers, four dropping core samplers, and five pushing core samplers. Some are popular for making sediment observations. However, others are unique and are not well known, although they have excellent characteristics. Their structures, merits, demerits, and suitable lake conditions are explained. Core samplers introduced are: Ekman-Birge grab sampler, Smith-McIntyre grab sampler, Rigo gravity corer, Limnos corer, Knocking corer, Mackereth piston corer, Proto-type pushing piston corer, Seto-type undisturbed separable piston corer, Suganuma-type portable percussion piston corer, Multisampler, and Russian Peat sampler.

著者

矢ヶ崎 典隆

出版者

Tokyo Geographical Society

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.89, no.3, pp.149-166, 1980-06-25 (Released:2010-10-13)

参考文献数

76

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Japanese immigrant agriculturists on the west coast of the United States in the pre-World War II period enjoyed a highly competitive position with their small but labor intensive operations even under social conditions that often discouraged their activities. One of the biggest factors in their competitive success in agriculture was their organizational effectiveness. Ethnic solidarity was maintained by first generation immigrants of most ethnic backgrounds both in fraternal and economic activities and they tended to cluster geographically and by occupation. But the Japanese agriculturists developed especially tight and efficient organizations to meet special needs and to protect themselves in this new and unaccustomed environment.The present paper describes and analyzes the development of Japanese floriculture in the San Francisco Bay Area from its beginnings in the late nineteenth century to the World War II relocation of the Japanese, with special emphasis on grower organizations as a key factor in their success.The early pioneering efforts and success of the immigrants, who were mostly of rural background, invited the participation of other Japanese in commercial flower production. The mild climatic conditions of the Bay Area, especially the absense of temperature extremes, were favorable for cut flower production, and the rapidly growing population created an increasing demand. Although two other ethnic groups, Italians and Chinese, were already in the business when the Japanese first started to grow flowers commercially, the industry itself was not fully organized. The Japanese thus moved into a niche that was waiting to be filled.In the early period the Japanese flower growers were mainly located in the East Bay region, producing carnations, roses and chrysanthemums in greenhouses. Marketing of flowers was undertaken on an individual basis, peddling them from wicker or bamboo baskets carried on the back or by opening flower stands on busy streets, which was generally inefficient and time consuming. As the number of growers increased and production expanded, intense competition developed among them. Gradually they became aware of a need for their own trade organization and marketing facility.

著者

安藤 萬寿男

出版者

Tokyo Geographical Society

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.97, no.2, pp.91-106, 1988-04-25 (Released:2009-11-12)

参考文献数

20

被引用文献数

4 3

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(1) In the lowland of the Kiso, Nagara and Ibi rivers, the people constructed embankments around the villages and arable land for the flood control to protect the villages from the flood. The flood control community is called Waju in Japanese.(2) People have long dwelled in the Waju region and a part of the dike was already built in the ancient time. But it is only in the early 17th century when the main parts of the Waju embankment were established for the first time. The construction of Waju increased since then.(3) When a Waju was established, the earth and sand were accumulated in the river bed. As a result, the river bed became so higher that the embankments were frequently broken in the feudal time. To cope with this situation, they raised the ground level of the building land and there built the mizuya in Japanese for an emergency evacuation. They used mizuya as a temporary house and a store-place of flood. Moreover, they raised the ground level with the earth produced by the digging of a moat in a part of the paddy. Through this procedure, the reduction of the rice production was prevented (horita in Japanese).(4) Since the Meiji era, the extensive river improvements by the government decreased the flood damage. And Waju, which was an unofficial organization in the feudal period, was controlled by a lower branch of the government's river administration.(5) In the Waju region, wet rice fields changed into dry ones in the Showa era. With increasing urbanization and industrialization, it became difficult to maintain the organization of the flood control. On the other hand, a new type of flood has also appeared.

著者

川幡 穂高

出版者

Tokyo Geographical Society

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.104, no.1, pp.1-15, 1995-02-25 (Released:2010-11-18)

参考文献数

61

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Several hundred years of astronomical observations have left no doubt that the Earth's orbit is subject to cyclic variations. While the annual energy receipt of solar radiation over the Earth as a whole is not change, the distribution of this energy, by latitude and by season, is affected by three parameters: an obliquity cycle of 41kyr, an eccentricity cycle of a quasi-period of 100kyr, and a precession cycle of 26kyr.The variance spectrum of the records of foraminiferal δ18O and magnetic susceptibility from Indian Ocean and organic carbon percentage from the equatorial regions of Pacific and Atlantic Oceans shows the well-documented concentrations of power at the orbital periodicities of 100kyr, 41kyr and near 23 and 19kyr. On the other hand, the resolution of the precessional bands in carbonate dissolution index is much less clear than those of obliquity and eccentricity bands. These results show that orbital forcing of global climate has strongly affected global carbon cycle. Detailed analysis of coherency and phase spectrum between δ18O and carbon-related data (i. e., carbon contents and isotopic composition) will improve our understanding global carbon cycle.

著者

薛 自求 松岡 俊文

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.117, no.4, pp.734-752, 2008-08-25 (Released:2010-04-27)

参考文献数

22

被引用文献数

28 22

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Several key questions need to be answered when CO2 geological storage is to be undertaken worldwide. How should CO2 be stored underground? Can trapping be assumed in saline formations and can CO2 be retained for long periods safely in the subsurface? The first Japanese pilot-scale CO2 sequestration project in Nagaoka was undertaken to provide answers to these questions. The injection site is located at the Minami-Nagaoka gas field in Nagaoka City, 200km north of Tokyo. Supercritical CO2 was injected into an onshore saline aquifer at a depth of 1,100m. CO2 was injected at a rate of 20 to 40 tonnes per day over an 18-month period, with a cumulative amount of 10,400 tonnes. A series of monitoring activities, which consisted of time-lapse well logging, crosswell seismic tomography, 3D seismic survey and formation fluid sampling, was carried out successfully to monitor CO2 movement in the sandstone reservoir. This paper presents an overview of the results obtained from both field and laboratory studies to examine the spatial-time distribution of CO2 and various trapping mechanisms in the reservoir. CO2 breakthrough at two of the three observation wells was clearly identified by changes in resistivity, sonic P-wave velocity and neutron porosity from time-lapse well logging. Each velocity difference tomogram obtained by crosswell seismic tomography showed a striking anomaly area around the injection well. As the amount of injected CO2 increased, the low-velocity zone expanded preferentially along the formation up-dip direction during the first two monitoring surveys and less change around the CO2-bearing zone could be confirmed from the following surveys. Unfortunately there was no significant change in 3D seismic results due to CO2 injection. The pilot-scale project demonstrated that CO2 can be injected into a deep saline aquifer without adverse health, safety or environmental effects. The Nagaoka project also provides unique data to develop economically viable, environmentally effective options for reducing carbon emissions in Japan.

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.35, no.8, pp.496-497, 1923-08-15 (Released:2010-12-22)

著者

日本地学史編纂委員会 東京地学協会

出版者

Tokyo Geographical Society

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.105, no.2, pp.215-237, 1996-04-25 (Released:2009-11-12)

参考文献数

150

被引用文献数

1 1

著者

飯塚 遼 太田 慧 菊地 俊夫

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.128, no.2, pp.171-187, 2019-04-25 (Released:2019-06-01)

参考文献数

41

被引用文献数

8 5

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With rapid globalisation and urbanisation, urban agriculture is experiencing many changes, for instance, in the preferences of consumers, who require more food security. In many cities across the world, urban agriculture is also positioned for food production and community building. In Japan, interest in urban agriculture has grown steadily, supported by the enactment of an urban agriculture law in 2015. Urban agriculture studies have been a controversial topic of research since around the 2000s in many academic fields, including geography. However, there have been few studies on the relationship between agricultural management, or farmers, and urban residents, although capturing interactions among urban residents as consumers and intentions for consuming urban agricultural space are critical when considering the sustainability of urban agriculture. Interactions are explored between farms and urban residents in the context of diversified agricultural management based on a case study using Kodaira city in the Tokyo Metropolis. Because the area is one of the urban agricultural areas of the Tokyo Metropolis, where many independent farmers survive, Kodaira city is a suitable study area to explore the diversification of farming and communication with urban residents. Literature, such as previous studies, is analysed. Then, public survey data is analysed to illustrate the spatial distribution of agricultural management patterns and classify them. In addition to qualitative analysis from field research, interviews with case farmers reveal the decision making of farmers in adopting specific methods of agricultural management and interactions with urban residents. Hence, interactions between farmers and urban residents exist based on agricultural management in Kodaira city. The classification of interaction styles is based on features of the area in a definite pattern. Such interaction styles prevent excessive competition among farms, attract stable customers, and realise sustainable management. Finally, urban agriculture in Kodaira city is founded on interactions with urban residents through the diversification of agricultural management.

著者

下鶴 大輔

出版者

Tokyo Geographical Society

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.98, no.6, pp.782-790, 1989-12-05 (Released:2009-11-12)

参考文献数

37

被引用文献数

4 1