著者

青木 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.126, no.4, pp.413-424, 2017-08-20 (Released:2017-09-27)

参考文献数

31

被引用文献数

2 2

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To investigate cliff recession processes and rates for the purpose of studying the development of horizontal shore platforms, data taken from a masonry seawall at Ashikajima located on the Choshi Peninsula coast is used. The seawall is composed of artificially cut blocks of Cretaceous sandstone, which is the same rock type as that forming shore platforms in the area. The seawall with a horizontal length of 100 m was built 90 years ago to protect reclaimed land on pre-existing shore platforms. Two sites are selected for this study: Site A without a shore platform in front of the seawall and Site B with a platform. The surfaces of sandstone blocks in the supratidal zone are depressed at both sites; Site B has a more noticeable depression. The depression depth (i.e. erosion depth) after the period of 90 years is considerably larger (more than double) at Site B than at Site A, in spite of Site A suffering direct attacks from waves, irrespective of tidal stages, while Site B experiences low-energy waves only during high tides due to the presence of the horizontal platform. Granular disintegration occurs markedly on the sandstone surface at Site B, but little occurs at Site A. This strongly suggests that salt weathering is prevalent at Site B, reducing the strength of rocks. The moisture content in sandstone blocks at Site B is lower than that at Site A, which implies that Site B is more susceptible to weathering than Site A which is always exposed to waves and tides. It would be reasonable to consider that the seawall at Site A is analogous to a cliff at the initial stage of platform development, while the seawall at Site B is similar to a cliff at its middle stage. Horizontal shore platforms start to develop due to wave action alone, but as they grow wider the importance of salt weathering increases and the combined effects of waves and weathering become crucial to platform development.

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.1, pp.Cover01_1-Cover01_3, 2011-02-25 (Released:2011-05-20)

参考文献数

4

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(表面)大陸は異なった時代につくられた造山帯のモザイクであるが,平均するとTTG組成をもつ.その大陸地殻は太平洋型造山運動でのみつくられ,現在までに地表面積の1/3を占めるまで増加している.そのほとんどは太平洋型造山運動によってつくられた.大陸の衝突による造山運動は既存の造山帯を変形再結晶させるだけで増加させることはない.大陸の造山帯のモザイクは,大陸の歴史を直接反映し,大陸地殻の形成プロセスを記録している. (裏面)第1大陸と第2大陸はTTGで構成されるが,第3大陸はアノーソサイト組成である(Kawai et al., 2009).第2大陸の分布はアジア大陸の下で最大のサイズに発達している.それは遷移層最下部(520-660km)だけでなく,下部マントル最上部にも漂移している.太平洋とアフリカ大陸直下の2つのスーパープルームとアジア直下の大下降流が地球内部の大局的なマントル対流である(Maruyama, 1994; Maruyama et al., 2007a, b).(丸山茂徳)

著者

丸井 敦尚

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.2, pp.172-181, 2014-04-25 (Released:2014-05-16)

参考文献数

22

被引用文献数

2

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The Kanto Plain is the biggest and deepest groundwater basin on the Japanese Islands. The water in the basin has been used in various purposes, and the volume of use is estimated to be the greatest in the country. Consequently, severe problems have emerged in the history of water development and water environment protection. The study show two stories in the groundwater basin of the Kanto Plain, corresponding to depth. The deeper one emphasizes salt water containing natural gas, and the shallow one is characterized by the largest groundwater flow system in the country. The paper reviews the geological features of the basin. Groundwater condition, especially deep groundwater, is also reviewed to understand the next stage of activities to develop and protect the environment.

著者

尾方 隆幸

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.viii, 2011-10-25 (Released:2012-01-17)

参考文献数

1

著者

三上 岳彦 大和 広明 広域METROS研究会

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.2, pp.317-324, 2011-04-25 (Released:2011-06-30)

参考文献数

10

被引用文献数

10 16

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This paper describes our newly developed high-resolution temperature observational system called Extended-METROS, which has been deployed in the Tokyo Metropolitan Area since 2006. Some climatological mean temperature charts using Extended-METROS data are analyzed in terms of urban climatology, and detailed urban heat island temperature patterns are clarified. Rainfall measurements were set up from August 2010 at 40 points in the Tokyo Metropolitan Area. The relationship between urban heat islands and local-scale heavy rainfall patterns in urban areas will also be analyzed based on our high-resolution meteorological observation system.

著者

木下 良

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.110, no.1, pp.115-120, 2001-02-25 (Released:2009-11-12)

参考文献数

24

著者

藤原 咲平

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.29, no.12, pp.769-783, 1917-12-15 (Released:2010-10-13)

著者

藤原 咲平

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.29, no.11, pp.701-712, 1917-11-15 (Released:2010-10-13)

著者

北里 洋

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.107, no.2, pp.258-273, 1998-04-25 (Released:2009-11-12)

参考文献数

87

被引用文献数

1 1 1

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To analyze oceanic paleoenvironmental histories, paleoceanography has used various biological proxies such as characteristic species, molecular bio-markers, chemical components and others. Much of paleoceanographic information originates from skeletal remains and/or chemical compounds of marine organisms. Accordingly, we are always faced with the biological problem of so-called “vital effects”. Experimental paleontology is a research method to determine relationships between organisms and their biotic and / or abiotic environments through well-controlled culture experiments. This is one of the best ways to shed light into the “vital effect” black box.In this article, I review previous studies which have tried to solve paleontological problems through culture experiments using foraminifera. There are three different scales of experimental methods. First is a culture in a petri dish. This method is advantageous to observe the relation between individuals and environmental factors. Second is micro-and mesocosm experiments which tried to reconstruct a part of the marine ecosystem in laboratory. With this method one can examine interactions between organisms and biotic and/or abiotic factors. Third is in situ experiment in the sea using submersibles or benthic landers. These methods play the role of finding clues about, or proving the nature of, currentbiological proxies of paleoceanography. I strongly invite young scientists to work with experimental cultures for the better understanding biological proxies in paleoceanography. Several suggestions for future studies are also proposed in the text.

著者

吉野 正敏

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.6, pp.836-850, 2007-12-25 (Released:2009-11-12)

参考文献数

91

被引用文献数

3 4

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Recent studies on climate change during the historical period are reviewed in this paper. Firstly, methods, limitations and materials for reconstructing past climates are summarized. Historic diaries and old documents are useful particularly for the period of the past 500 years. Some indices for expressing the climatic conditions found in the historic materials are introduced. Historic documents and materials found in China since 4, 000 BP were published in 2004. On the other hand, daily weather data at several stations for the 15 and 16 centuries in Japan were published in 2004 and 2006, respectively. Secondly, the “Little hypsithermal (warm) period” during the period from the 4th century to the 10th century is described. In the final part of the present paper, examples of an ancient central government in Japan, planning of Heijoukyou (an old center of government), settlements developed on the Boso Peninsula, Chiba, Japan, and parallel activities in Southeast Asia are discussed in relation to the changing climate during the “Little climatic optimum” from the 8th century to 9th century, which was the peak of the “Little hypsithermal (warm) period”. It is pointed out that the changes were roughly in parallel.

著者

澤柿 教伸 平川 一臣

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.107, no.4, pp.469-492, 1998-08-25 (Released:2010-10-13)

参考文献数

120

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Geomorphological and sedimentological processes beneath modern glaciers and ice sheet s have not been observed directly and are poorly understood. On the contrary, abundant glacial landscapes can be observed, which provide us with evidence about processes underway at the beds of the past ice sheets. Consequently, careful studies of glacial landforms and sediments provide a wealth of information of these processes.During the last decade, there have been various debates regarding subglacial landforms and their formation processes: drumlins is a major issue, and no satisfactorye xplanation of their mode of formation has yet been obtained. By overviewing recent research on the drumlin problem, this article attempts to draw attention to the major concepts and controversies behind the formation of subglacial landform, together with new developments in understanding the subglacial environment. The most recent explanations for drumlin formation have been examined in the light of our knowledge of the subglacial environment. In particular, J. Shaw and his co-workers draw attention to the significance and the implication of subglacial meltwater processes. They suggested that large-scale meltwater floods were responsible for the formation of some drumlins. Later, erosional drumlins, bedrock erosional marks, tunnel channels, and Rogen moraine were added to the forms resulting from catastrophic floods. Conversely, G.S. Boulton developed a semi-quantitative flow model for the deformation of rapidly deforming soft sediments (A-horizon) on the basis of field observations.The drumlin problem stands as a conspicuous instance of how much there is still to understand about the interplay of glacier motion, sediments, topography, and subglacial environmental conditions. It is thus emphasized that accumrate explanations of the complexities of subglacial environments are necessary to understand subglacial landform development, sediment deposition, and other geomorphic processes at the ice/bed interface, together with extraglacial effects of ice sheet dynamics on fluvial systems, marine sedimentation, ocean currents, and climate.

著者

丸山 茂徳 宇都宮 敦 石川 晃

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.6, pp.1035-1044, 2011-12-25 (Released:2012-03-05)

参考文献数

16

被引用文献数

1

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オントンジャワ海台は太平洋中央部の太平洋スーパープルームによって白亜紀(122 Maと90 Ma)につくられた巨大な海台である。形成後,西方に移動し,オーストラリアプレートが北上することによってプレート相対運動が変化して,20-25 Maごろから海溝に沈み込みはじめた。その結果,ソロモン諸島には,それらの海台の破片が付加体として露出している。付加しはじめた時期については異論があり,これまでの多くの研究者は2 Ma 以降であると考えてきた。 しかしながら,われわれは地質調査と文献に基づいた証拠,すなわち一連の逆断層の形成と構造浸食,および20-25 Ma以降の沈み込み帯火山活動の停止から以下の解釈を行った。海台が25-20 Maに海溝に沈み込みを開始すると,海台のその浮力のために、沈み込み角度が低角度になり島弧火山活動が停止した。そして始新世以降の付加体を構造浸食して,崩壊物をマントルへと運んだ。また中新世におけるオントンジャワ海台の衝突と沈み込みが背後のウッドラーク海盆の拡大の開始のトリガーになったと思われる。 過去25-20 Maにわたるオントンジャワ海台の沈み込みは,付加体としては海台のごく一部(< 1%)のみを上盤側のプレートに付加したのみで,主要部のほとんどはマントル深部へ沈み込んだと思われる。これは顕生代の環太平洋造山帯に普通にみられる現象である。

著者

山口 貞雄

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.44, no.10, pp.549-561, 1932-10-15 (Released:2010-10-13)

参考文献数

12

著者

早川 由紀夫

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.108, no.4, pp.472-488, 1999-08-25 (Released:2009-11-12)

参考文献数

94

被引用文献数

3 9

著者

小口 高 斉藤 享治 原 美登里 門村 浩 林 舟

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.109, no.1, pp.120-125, 2000-02-25 (Released:2010-10-13)

参考文献数

18

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Data for Japanese alluvial fans have been made available on the Internet using ArcView IMS, a GIS-based map server software package. This system permits easy on-line browsing of the data from anywhere in the world and the creation of thematic maps at various scales for the area around an alluvial fan.

著者

早川 由紀夫 藤根 久 伊藤 茂 Lomtatize ZAUR 尾嵜 大真 小林 紘一 中村 賢太郎 黒沼 保子 宮島 宏 竹之内 耕

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.3, pp.536-546, 2011-06-25 (Released:2011-09-06)

参考文献数

11

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Two wood trunks, one charred and 75 years old and the other not charred and more than 199 years old, were collected from Hayakawa ignimbrite of Niigata Yakeyama Volcano. They were investigated using the radiocarbon wiggle-matching method to determine the age of the eruption. The result was 1225-1244 cal AD (95.4%), which is over 200 years younger than previous estimates. The eruption, including the Hayakawa ignimbrite, was the largest during the volcano's life period of 3000 years. Co-ignimbrite fallout KGc ash has been found at many archaeological sites spreading on the eastern flanks of Myoko Volcano and the Takada Plain. The age obtained here will provide a useful time constraint for archaeologists and volcanologists studying this area.

著者

林 上

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.106, no.6, pp.794-798, 1997-12-25 (Released:2009-11-12)

被引用文献数

1 1 1

著者

浦 環

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.109, no.6, pp.900-906, 2000-12-25 (Released:2009-11-12)

参考文献数

12

被引用文献数

3

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The autonomous underwater vehicle (AUV) has been recognized as a new platform for observing the underwater world. It can dive freely around the target of the mission prescribed in its computer prior to launching.Throughout a dive, it does not require the operator and the support vessel to help it to execute its mission. It has no umbilical cable, which is fitted to remotely operated vehicles currently used for underwater operations and observations and usually causes problems for the operator. This paper presents the state of the art of the AUV and how it can be used in underwater science.

著者

貝塚 爽平

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.66, no.4, pp.217-230, 1957-12-30 (Released:2009-11-12)

参考文献数

23

被引用文献数

2 2

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The northeastern part of the Kantô plain, which is the largest plain in Japan, has many terraces as shown in the geomorphological map (fig. 1).In this paper, the landdforms and the geological structures of these terraces are described as below.(1) General characteristics of the terraces.The above area is divi ed into two topographic regions by the Yamizo mountain range running from north to south. The estern part is practically made up of marine Pleistocene strata. On the other hand, the western part has many river terraces which are formed by fluvial gravels and volcanic ashes.(2) Dating of the terraces by tephrochronology (tehro means volcanic ashes).During the Quaternary period, the terraces had been covered by volcanic ash layers called Kanto Loam. Presently the older terraces and the newer ones both are covered by thick and thin Loams respectively. This relationship between terrace and Loam makes it possible to date the land surfaces chronologically. Through this the author obtained the following chronological table.(3) The river terraces built by eolian volcanic ashes.The western area is chiseled off by many river terraces. In the northern part of this terraces region, the relative heights of terrace surfaces from the preseat flood plain are higher than that of the southern part. But, if the volcanic ashes on the whole terraces are stripped off, the surfaces of the terraces have practically no significant heights, In other words, the higher the terraces, the thicker the volcanic ashes are as shown in Fig. 4, In conclusion, these river terraces would be called “Eolian volcanic ash terraces”.

著者

杉戸 信彦 松多 信尚 石黒 聡士 内田 主税 千田 良道 鈴木 康弘

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.2, pp.157-176, 2015-04-25 (Released:2015-05-14)

参考文献数

15

被引用文献数

5 8

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Spatial variations of hazards such as strong ground motion and tsunami inundation are a key element for obtaining a geographical understanding of natural disasters. However, detailed distribution of tsunami run-up heights for the devastating tsunami associated with the 2011 off the Pacific coast of Tohoku earthquake is not available. A GIS analysis of tsunami inundation areas is conducted from data collected by the Tsunami Damage Mapping Team and from post-tsunami 2-m mesh and 5-m mesh digital elevation models (DEM) after the Geospatial Information Authority of Japan, in order to produce the Tsunami Run-up Height Map, which includes polygon data of inundation areas with elevation data at each point. Horizontal shifts of orthophotos taken just after the tsunami are corrected using a Helmert transformation. The map covers Iwate Prefecture, Miyagi Prefecture, and the northern part of Fukushima Prefecture continuously at high resolutions, and reveals spatial variations of tsunami run-up heights in detail. These variations are caused by: 1) landforms at each site, such as coastal plains, valleys, bays, and beach ridges, as well as their directions and magnitudes, and 2) source locations, interference, and wavelengths of the tsunami, as implied by a previous study. The map supports examination carried out on source fault models and simulation results of tsunamis from a geographical viewpoint. At the same time, the methodology to produce the map would be useful for systematically revealing run-up height distribution, in addition to inundation areas immediately after future tsunamis.