著者

佐藤 大祐 澁谷 和樹

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.124, no.6, pp.965-977, 2015-12-25 (Released:2016-01-27)

参考文献数

27

被引用文献数

2 5

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The development process and usage patterns of second-home areas at the foot of Mt. Fuji are clarified by analyzing their expansion process, capital, and owner behavior. After World War I, in 1929, Fuji Kyuko Company, profiting from a business boom, started to develop a second-home area south of Lake Yamanaka [Yamanaka Kohan Bessochi]. This approach, by which a private company borrowed a section of Imperial Gift Land from Yamanashi Prefecture and established a second-home area, served as a model for developments at the northern foot of Mt. Fuji. In the early 1960s, second-home areas were developed north of Lake Yamanaka and at Fujizakura Highland south of Lake Kawaguchi. With the opening of the Chuo and Tomei Expressways in 1969, there were large capital flows into the creation of up-scale second-home areas at Juriki Highland, Fujigamine Highland, and Asagiri Highland, as well as around Lake Kawaguchi from the late 1960s until the mid-1970s. Large railway, trading, and paper manufacturing companies, as well as local developers, started to create second-home areas throughout the high-growth period. These investors, therefore, competed for land at the foot of Mt. Fuji. As a result, speculative capital flowed into development projects in second-home areas. This speculation created the potential for massive environmental destruction. Consequently, local governments concluded agreements with second-home owners' associations to clarify management responsibilities. Owners are most frequently at their second homes on weekends and during summer vacations in the hot months from mid-July to mid-September when temperatures at the foot of Mt. Fuji are below 30°C. Owners also visit frequently at weekends and holidays in the spring and autumn. The second-home areas around Mt. Fuji, therefore, are both summer and weekend resorts, because they are located within a two-hour commute from Tokyo by car. The second-home areas, moreover, receive many migrants from urban areas, including aged persons, who seek an attractive natural environment at a relatively low price.

著者

井関 弘太郎

出版者

Tokyo Geographical Society

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.84, no.5, pp.247-264, 1975-10-25 (Released:2009-11-12)

参考文献数

52

被引用文献数

5 10

---

Alluvial plains in the coastal regions of Japan are considered to have developed according to the following processes : during the last glacial stage when the sea level was lowered, rivers dissected their valleys downward to that level. After then, in consequence of the postglacial rise of the sea level, these valleys were drowned and were filled up with Flandrian deposits.The bottom floors of such buried valleys are mostly found at 30-80 meters below the present sea level. These bottom floors in many cases are covered with fluvial gravel beds about 10-20 meters thick. Such gravel beds are mostly overlaid with sediments of finer materials which deposited in the shallow sea during the late and post glacial transgression. They are called “Basal Gravel Beds” of the Recent deposits by the present author. They have probably been formed when the lowering of the sea level reached the limit during the last glacial stage. The huge accumulation of gravels as the Basal Gravel Beds might have been brought on by the overloaded streams which carried much detritus as the production of the strong physical weathering under glacial or periglacial conditions during the Ice Age. The author found that some of the Japanese alluvial fans of a large scale are formed by Recent Basal Gravel Beds.The maximum accumulation of the ice during the last glacial stage should be enough to cause a lowering of the sea level of about 80-15 meters below that of the present. In order to get a acceptable figure regarding the lowering of the sea level or the lowest sea level during the last glacial stage, the author, presuming the figures-100 and-140 meters as the postulated low sea level stand, examined the depth of these floors of buried valleys, respectively.Based on the results of borings which were carried out with 21 major buried valleys in Japan, the depth from the surface of present-day alluvial plain to the upper face of Basal Gravel Bed which covered bottom floor of buried valley was measured in each alluvial plain and then the relation between the depth of the deepest bore hole and the distance from the mouth of the old valley to that bore hole site was investigated (Fig. 3 and 4). The correlation coefficient between the depth and distance was also calculated.Fig. 3 indicates the case in which the sea level was presumed to be 100 meters below that of the present and Fig. 4 in the cases of-140 meters, respectively. Is is obvious from these two charts that the depth of the deepest bore hole negatively correlates with the distance from the mouth of buried valley to that bore hole site. So far as the correlation coefficients are concerned, being-0.870 and-0.890, respectively, the presumed figure of the latter seems to be more acceptable than that of the former. Therefore, judging from the depth of buried valley floors, the author is of the opinion that the figure-140 meters as the lowest sea level during the last glacial stage should be more acceptable than that of-100 meters.

著者

永田 武

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.100, no.1, pp.150, 1991-02-25 (Released:2009-11-12)

著者

池原 研

出版者

Tokyo Geographical Society

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.107, no.2, pp.234-257, 1998-04-25 (Released:2009-11-12)

参考文献数

134

被引用文献数

1 1

---

Marginal seas, such are located as Bering Sea, Okhotsk Sea, Japan Sea, East China Sea, South China Sea and Indonesian seas, locate along the western rim of the Pacific. They have only a small area but are regions of high biological productivity, and thus expected to play an important role on global environment. Each of them has an unique characteristics on bathymetry, water exchange between the adjacent marginal seas and/or open ocean, primary productivity and volumes of fresh water input and terrigeneous material supply. Because they connect each other and to the open ocean through the shallow straits, characteristics of water masses flowed into the marginal seas were highly influenced by global sea level fluctuations. Furthermore, climatic change affected the volume of terrigenous supply to the seas. Therefore, paleoenvironments of the marginal seas largely changed with long-term sea level changes and short-term climatic changes. Recent studies on paleoceanography of the Japan Sea and the South China Sea suggest the importance of Asian monsoon to control the oceanic environments of the marginal seas. Hemipelagic sediments with higher sedimentation rates in the marginal seas recorded paleoceanographic changes in high resolution. Multidisciplinary studies for large-diameter long piston cores from the East Asian marginal seas may provide good information for global climate changes in the late Quaternary.

著者

石川 有三

出版者

Tokyo Geographical Society

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.110, no.4, pp.592-601, 2001-08-25 (Released:2009-11-12)

参考文献数

26

被引用文献数

4 5

---

The shape of the Philippine Sea slab beneath southwest Japan was investigated using the hypocenter distribution and the fault plane solutions obtained by Japan Meteorological Agency. Two seismic belts were found in an equal depth section of the slab and these did not relate to the double seismic zone in the subducting slab. Then, the existence of a broken off piece of slab was proposed beneath Kii channel. This piece collided with Philippine Sea slab and created a high seismicity area at each side.Three events that were not located at a high seismic area in the slab were found. Two were considered to be the events that occurred at the near aseismic part of the slab. The other may have occurred at another broken off piece of the slab.

著者

山下 亜紀郎

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.122, no.6, pp.1039-1055, 2013-12-25 (Released:2014-01-16)

参考文献数

27

被引用文献数

1 4

---

The purpose of this study is to review the history of urban water use in Tokyo focusing on two water sources: surface water and groundwater. First, the following four matters are picked up chronologically: expansion of metropolitan waterworks, enhancement of surface water resources, progress of land subsidence, and groundwater pumping. Second, the change of groundwater use and current conservation policies are clarified for some municipalities. Finally, sustainability of urban water use is discussed. Originally, the water source of metropolitan waterworks was surface water. With increased water demand, the waterworks developed surface water resources in areas remote from Tokyo. Despite increased water demand, groundwater pumping was restricted because of serious land subsidence. Industrial water shifted the water source from groundwater to surface water with the construction of industrial waterworks. On the other hand, groundwater use as residential water has been partially maintained in the Tama Region, western Tokyo. Municipalities in the Tama Region promote policies to maintain groundwater use and recharge. For sustainable urban water use, efforts both to avoid a further increase of water demand and to maintain local groundwater resources are necessary. Moreover, in terms of water security at the time of a disaster or water shortage, a sustainable urban water supply system should include both an extensive water supply system and a local system of water supply.

著者

菊地 俊夫 岩田 修二 渡辺 真人 松本 淳 小出 仁

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.5, pp.729-732, 2011-10-25 (Released:2012-01-17)

参考文献数

14

被引用文献数

7 6

著者

スンドボリィ オーケ

出版者

公益社団法人 東京地学協会

雑誌

地学雑 (ISSN:0022135X)

巻号頁・発行日

vol.87, no.3, pp.115-129, 1978

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この論文は, 異った気候下の河川営力についての一般的議論を含んでいる。自然の河川営力の正当な知識が, 純粋に科学的理由にとって又社会的利益にとって, きわめて重要である。将来の開発について予測し得る環境危険因子の予報は, 物理的計画においては本質的な要素である。水文学的法則 (regime) と沈積物生産とは, 気候によって大きく支配される。併し, それらは又相互に関連し, 殆んど独立していない多数の異った因子によって影響される。植生, 基盤岩石, 土壌条件, 地形, 水路形態 (geometry) が, これらの因子の若干例である。いくつかの典型的な例が, 異った気候地域からあげられる。北極地域において河流の営力に関する永久凍土の影響が議論され, 例証される。湿潤中緯度気候では, 季節性や冬季の雪氷のあり得る存在の影響が, 他のものとの問で, 議論される。乾燥気候においては植生の部分的欠除や, 大量の急激な洪水流の生起が議論され, それらの営力における意義が強調される。乾燥地帯における, 河流営力とくに河床荷重の運搬と地形景観の一般的地形学的発達との問の密接な関係が指摘される。熱帯では, 植生は他の因子と共にかなり重要な役割を演ずる。例えば, 火山地域における「ラハール」の作用は又, 川の性格に関して重要であるだろう。<BR>結語の部分では, いくつかの一般的概念が提示される。基礎的な水力学的作用と河川の営力は, 気候や他の外的条件にかかわらず同じであり (同一性の概念), 又多くの川の営力の率とその地形学的堆積学的結果は直接, 間接に, 気候たとえば永久凍土, 河氷, 雪と植生によって支配される (気候制約の概念) ことが指摘される。すべての川には流量と沈積荷重との間に, 河流の営力と地形発達の一般的性格を決定する均衡及び均衡に準ずるものがある (水と沈積物の関連) 。川の作用は, 又流域の他の部分における条件と作用によっているので, 全流域を複合単位として取扱うことが必要である (基礎的単位としての流域) 。異った頻度と大きさについての地形学的事象の重要性は気候と共に変化する。これは更なる研究の重要な課題である (頻度と規模の関連) 。川の営力における人の影響は, 次第に, より重要になっている。人間活動の影響の予測に充分な方法を開発することが必要である (人間の影響) 。営力地形学は長い期間の地形発達において, 気候や他の因子たとえば人間の影響までを蔽って用いることにより, 有用な語となるだろう。

著者

ダビターヤ F. F.

出版者

Tokyo Geographical Society

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.76, no.3, pp.154-158, 1967

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自然は絶えず変化している。自然のままの状態では気候の変化が最も速やかに行なわれ, 植生や地形の変化は何世紀, 何十万年という速度で進行する。しかしいったん人為が加わるとそれぞれ変化の速度が異なってくる。人為の影響を受けやすいのは植生で, 気候はいちばん遅れて変化が現われるようになる。気候・植生・土壌などによる地域区分の境界線が一致しないのは, それぞれ変化の速度に違いがある以上当然だといえる。<BR>今世紀になってから人間の活動はますます活発になって, 森林の減少, 草原の砂漠化, 河川の汚染, 地たりの激化などが急速に進んでいるので, このままでは大きな弊害が生ずるであろう。影響を受けるのが遅いはずの気候でさえも人間の影響を無視できなくなってきている。Budykoの計算 (1962) によると年々太陽から得ている熱量は49kca1であるのに対して, 世界中の人間が出している熱量は0.02kcal/cm<SUP>2</SUP>/yrであるが, これが毎年10%ずつ増えているとすると100年以内に太陽からの熱量に匹敵する量になる。また, 人間活動によつて大気中の炭酸ガスの量が増加して気温が上昇することも考えられる。一方, 水蒸気量や雲量や塵埃量の変化がこれらの効果を強めたり弱めたりする。量的な研究はまだ進んでいない。<BR>最近50~100年間に気温の上昇が認められている。1940~50年から再び下降の傾向を示しているが, 上昇がもう終わってしまったのか, 一時的な変動であるのかは今のところわからない。気候の温暖化と氷河の後退との関係はなかなか複雑で一義的には決まらない。気候温暖化の主因は大気大循環にあると考えられているが, 地球全体が温暖化することを説明できない。炭酸ガス説も不十分である。人工発熱量も現在までのところ問題にならないくらい小さい。<BR>そこで気候温暖化の一因に大気中の塵埃量の増大が考えられる。ここに逆説的な観測事実が二つある。一つはコーカサスと中央アジア地方の高山で過去50~70年の間に, 降水量は同じか増加し, 気温は下降の傾向を示しているのに氷河が後退していること, もう一つは融けっっある氷の表面の温度が0度以上であることである。これらは最近大気中の塵埃量が増えてきていることで説明がっきそうである。<BR>大気中の塵埃は宇宙塵, 海成の塵埃, 火岸灰による塵埃, 風成の塵埃, 工業による塵埃などであるが, 最初の三つは少量で変化も小さい。大気中の全塵埃の70~75%を占める風成の塵埃は森林の伐採, 耕地の開拓などによつて近年急速に増加した。工業による塵埃も相当量にのぼる。ソ連各地の直達日射量の観測結果からも1920年ごろから塵埃量が著しく増加したことがわかる。<BR>このような最近の自然現象の変化の方向や強さを研究するためには, 全地球的規模の計画に従つて同時観測を実施することが必要である。そしてこのような観測の計画を樹てるためには世界各地の地理学者の協力がなければならない。

著者

新井 健司

出版者

Tokyo Geographical Society

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.105, no.4, pp.485-491, 1996-08-25 (Released:2009-11-12)

参考文献数

9

著者

岩塚 守公

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.80, no.1, pp.63-64, 1971-02-25 (Released:2009-11-12)

著者

尾鼻 浩一郎 藤江 剛

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.126, no.2, pp.113-123, 2017-04-25 (Released:2017-06-12)

参考文献数

34

被引用文献数

2 2

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An important site of hydration and alteration of the incoming oceanic plate prior to subduction, the trench-outer rise region determines the distribution and amount of water transported into the Earth's mantle by subduction of the oceanic plate. Recent seismic surveys conducted in the northwest Pacific Ocean indicate reductions of seismic velocities within the oceanic crust and the uppermost mantle of the incoming Pacific plate toward the trench. These velocity reductions probably reflect hydration and alteration of the Pacific plate prior to subduction, although there are regional variations in the crustal structures of the oceanic lithosphere. Besides structural change, the stress regime within the incoming Pacific plate, which is derived from seismicity observations in the trench-outer rise region of the Japan Trench after the 2011 Tohoku-Oki earthquake, suggests that extensional stress of the incoming Pacific plate extends down to a depth of about 40 km. However, normal-faulting earthquake activity within the incoming Pacific plate was limited at depths shallower than about 20 km before the 2011 Tohoku-Oki earthquake. The change of the depth extent of normal-faulting earthquake activity suggests that the 2011 Tohoku-Oki earthquake changed the stress regime within the incoming Pacific plate. Distribution and focal mechanisms of shallow seismicity within the oceanic crust indicate that seismicity is affected by the pre-existing structure, which probably formed at the mid-ocean ridges. Heterogeneity and pre-existing structure of the incoming oceanic lithosphere should be taken into account when considering hydration and alteration of the oceanic lithosphere subducting into the trench.

著者

大場 忠道

出版者

Tokyo Geographical Society

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.115, no.5, pp.652-660, 2006-12-25 (Released:2009-11-12)

参考文献数

11

被引用文献数

4 8

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Five distinct paleoenvironmental changes in the Japan Sea over the last 95 ka are revealedfrom the oxygen and carbon isotopes of foraminiferal tests in a piston core recovered from the Oki Ridge. Between 95 and 27 ka, the warm Tsushima Current did not flow into the Japan Sea.The environment at the seafloor fluctuated between anoxic to weakly oxic conditions. Between 27and 17 ka, freshwater input to the Japan Sea, probably from the surrounding land, stratified the water column, and the resulting severe anoxic conditions eliminated most benthic fauna. Between 17 and 10 ka, the cold Oyashio Current flowed into the Japan Sea through the Tsugaru Strait, reestablishing deepwater ventilation. Between 10 and 8 ka, bottom conditions changed from anoxic to oxic. At 10 ka, the warm Tsushima Current started to flow into the Japan Seathrough the Tsushima Strait, establishing the modern oceanographic regime at 8 ka.From high-resolution oxygen and carbon isotope analysis of both benthic and planktonic foraminifera from an IMAGES core collected from off Kashima, central Japan, very large (20°C) sea surface temperature (SST) fluctuations can be reconstructed for the last 150 kyr, with minimum SSTs of 3-4°C during Marine Isotope Stage (MIS) 2 and MIS 6/5e transition, and with peak SSTs of 22-23°C during early MIS 1 and MIS 5a/4, 5c/5b, and 5e/5d transitions. The SSTs varied in parallel with changing carbon isotope differences between Globorotalia inflata and Globigerina bulloides, which suggests that the SST changes were primarily caused by latitudinal displacements of the Kuroshio-Oyashio Currents. A strong correlation between the SST shifts and orbital forcing indicates that latitudinal displacements of the Kuroshio-Oyashio Currents were influenced by summer insolation at 65°N.

著者

藤井 敏嗣

出版者

Tokyo Geographical Society

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.97, no.3, pp.209-213, 1988-06-25 (Released:2009-11-12)

参考文献数

22

著者

佐藤 暢 谷口 英嗣 高橋 直樹 MOHIUDDIN Mia Mohammad 平野 直人 小川 勇二郎

出版者

公益社団法人 東京地学協会

雑誌

地學雜誌 (ISSN:0022135X)

巻号頁・発行日

vol.108, no.3, pp.203-215, 1999-06-25

参考文献数

63

被引用文献数

1 10

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Geological, petrological, and biostratigraphical studies of Mineoka ophiolite and related rocks, Hayama and Mineoka Belts, central Japan, were reviewed, and the origin of ophiolite is summarized as follows. 1) Pelagic to hemipelagic sedimentary rocks occur from late Paleocene to middle Miocene. 2) Basaltic rocks in the Hayama Belt are mostly alkali basalts of hotspot origin, whereas those in the Mineoka Belt are mostly tholeiite of mid-ocean ridge origin. 3) Chemical compositions of gabbros and diorites indicate island arc origin. 4) Peridotites are residues after a medium degree of partial melting. These facts arenot consistent with previous ideas that the ophiolite is island arc or back arc originonly. &ldquo;It is concluded that ophiolite is part of the Mineoka plate&rdquo; in the Pacific Ocean side, not in the Philippine Sea as previously proposed. Reconstruction of plate motions of the Mineoka plate is proposed, as it was formed at mid-ocean ridge, was subducted by the Pacific plate, and obducted to the Honshu arc during Miocene age after the eastward motion of the triple junction.

著者

村田 明広

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.82-93, 1995-02-25 (Released:2010-11-18)

参考文献数

24

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The Paleogene Hyuga Group of the Aradani Area in East Kyushu is regarded as an accretionary complex in the Shimanto Terrane. The Group was formerly inferred to form a melange including various sized blocks of sandstones, red and green siliceous mudstones, and basaltic volcanic rocks. The siliceous mudstones are not blocks in the melange, but occur as a low-angled thrust sheet of 40m thick.The Hyuga Group of the Aradani Area consists of four tectonic units;(1) lower chaotic unit, (2) siliceous mudstone unit, (3) mudstone unit, and (4) upper chaotic unit in ascending order. Each unit except for the siliceous mudstone unit forms a duplex structure, in which strata are imbricated, dipping 30° to 50° Each duplex is formed by mono-lithologic strata. The fundamental structure of the Paleogene Shimanto Terrane in Kyushu is characterized by low-angled nappe structures with stacked duplexes, in which duplexes lie one above the other, similarly to those of the Cretaceous Uchinohae Formation in South Kyushu.Original succession of the Hyuga Group is (1) basaltic volcanic rocks, (2) red and green siliceous mudstones of Middle Eocene, (3) black mudstones of Late Eocene, (4) sandstones and alternating beds of sandstone and mudstone of Late Eocene to Early Oligocene. Chaotic beds of melange facies originate from all above-mentioned strata. The siliceous mudstones, which are considered to be hemipelagic sediments, were subducted, and then formed a thrust sheet during underplating. The siliceous mudstones were probably situated in the decollement horizon, but did not flow as a lubricant layer.

著者

歌代 慎吉 岩淵 義郎

出版者

Tokyo Geographical Society

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.80, no.2, pp.77-88, 1971-04-25 (Released:2009-11-12)

参考文献数

8

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Sagami Bay is structurally active area through the geological history, and also the epicenter of the Great Kanto Earthquake (1923) was here. To make clear the features of the topography and geological structure of the active area, it seems to be fundamental step for the earthquake predication today.In April to May 1968, the surveying ship Meiyo of the Japanese Hydrographic Office carried out the sea bottom surveys of Sagami Bay with echo-sounder, seismic profiler and proton-geomagnetometer, including the dredge and coring operation, and took the data from about 3000 kilometers of her traverses.The ship's position was mainly determined by an auto-tape system with the estimated accuracy of ±2 meters. The simultaneous measurement of magnetic intensity, bathymetry and submarine geological structure by air-gun system allows direct comparison of the measurements. Figure 1 is the track chart of the Meiyo and figures 2 and 3 are some profiles based on the collected data.From the analyses of the collected data mentioned above, the topography and geological structure and magnetic anomaly of Sagami Bay can be summarized as follows.1. TopographyFigure 4 shows the bathymetric chart of Sagami Bay. In the eastern part of the bay, many banks and small basins range from NW to SE. Many submarine canyons cross the topography mentioned above and incise deeply, so that especially small basins do not keep their complete shape.The central part of the bay is called Sagami Trough, which is deeper than 1 kilometer. The floor of the trough generally shows low relief with the exception of the eastern part of the trough, which submarine canyons flow into, and gentle slope with the trend of NS at the central part, facing east and reflecting the fault topographically.In the western part of the bay, continental shelf and slope are monotonous, comparing with its eastern part. There are several conical banks between the Izu Peninsula and O Shima Island.2. Geological structureGeological structure based on the seismic profiler is shown in Figure 5. The area surrounded Sagami Bay is relatively uplifted zone in contrast with the trough showing the relative subsidence. Acoustic basement rock outcrops on the uplifted zone and may probably be composed of the Hayama group (Lower Miocene) and partly the lower part of the Miura group (Middle Miocene).The large part of the thinly layered sediment at the upper part of sediment body in Sagami Trough is younger than the age of uplifted zone mentioned above. The layered sediment is wholly tilted to the axis of the trough, and is found the folding in the margin of the trough and also the active fault near surface. Its maximum thickness is found at the northern part of the trough, and is over about 1 second in the reflection time approximately.The area along the Izu Peninsula and around O Shima Island is extensively covered with the volcanic products. Small banks between the Izu Peninsula and O Shima Island are volcanic cones of the effusive body which pierced through the layers probably composed of the Shirahama group (Middle to Upper Miocene).3. GeomagnetismThe resultant magnetic chart, contoured at intervals of 100 gammas, was in Figure 6. The results of the magnetic surveys revealed that there were many magnetic anomalies of about 500 to 800 gammas off shore along the Izu Peninsula in Sagami Bay and a pair of remarkable positive and negative magnetic anomalies of about 1800 gammas in the sea area along the west side of O Shima Island.On the other hand, it was found that there was no remarkable magnetic anomaly in the central part and eastern part of Sagami Bay.From the results of magnetic surveys and submarine geological structure, it can be concluded that the sea area off shore along the Izu Peninsula and around O Shima Island are composed of volcanic rocks of higher magnetic susceptibility, such as basalt or andesite.

著者

小山 拓志

出版者

東京地学協会

雑誌

地學雜誌 (ISSN:0022135X)

巻号頁・発行日

vol.120, no.6, pp.981-992, 2011-12-25

参考文献数

19

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Turf scarps and patch-shaped barelands are clearly observed on windy alpine ridges and wind-swept slopes of Japanese mountains. This study investigates the formation and retreat of turf scarps at the Daisyoujidaira site (2700 m a.s.l.) and Maru-yama site (3025 m a.s.l.), Southern Japanese Alps.<br> The average distances of scarp retreat are 2.2 cm/2 years (Daisyoujidaira site: 2006-2008), 0.5 cm/year (Maru-yama site: 2006-2007), and 3.6 cm/year (Maru-yama site: 2007-2008).<br> At the Daisyoujidaira site, generation of turf scarps started on the walls of trails or gullies. The retreat processes of turf scarps are considered to be a combination of frost-thaw action (needle ice creep), deflation, rain-splash erosion, and slope wash. However, at the Daisyoujidaira site, turf scarps with curtain-like exposure of plant roots are protected from deflation and rain-splash erosion during summer.<br> On the other hand, at the Maru-yama site, eave collapsing and turf plucking occur frequently, and turf scarps continue to retreat. As a result, patch-shaped barelands continue to expand on the wind-swept slope of Maru-yama.

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.7, no.10, pp.567a, 1895-10-10 (Released:2010-12-22)

著者

吉岡 真弓

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.123, no.4, pp.472-485, 2014-08-25 (Released:2014-09-01)

参考文献数

42

被引用文献数

2

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Besides the immediate need for alternative sources of energy, it has become increasingly crucial to maximize the use of the limited energy sources that remain after the Great East Japan Earthquake. Tokyo, which consumes an enormous amount of energy, should lead this effort by exploring ways of becoming an advanced energy-saving city in the future. This paper focuses on the thermal energy of water, which is one of the available energy sources in Tokyo. The potential of the thermal energy of water could be harnessed to improve the thermal environment and reduce energy use in Tokyo. One way to use this energy is to harness the heat of evaporation by sprinkling water on a pavement in order to improve the thermal environment in summer in cities where the heat island phenomenon is observed. This technique of sprinkling water is known to the Japanese as Uchimizu, and it is a time-honored custom in Japan. Some studies involving field experiments and numerical simulation have investigated the cooling effect of sprinkling water scientifically by applying systematic sprinkling as a countermeasure for the formation of heat islands. The other way of employing this source of energy is to use a ground-source heat pump system, which is a high-performance cooling and heating system, using subsurface and groundwater thermal energy efficiently. Active use of thermal energy of water is considered to be one strategy that Tokyo can adopt to become an energy-saving and environmentally friendly city in the future.