著者

八木 勇治 菊地 正幸

出版者

Tokyo Geographical Society

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.112, no.6, pp.828-836, 2003-12-25 (Released:2009-11-12)

参考文献数

46

被引用文献数

1 5

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Resent studies on relationship between sites for co-seismic slip and a-seismic slip are reviewed. Through analysis of seismic wave and Global Positioning System (GPS) data set, the sites for co-seismic slip and a-seismic slip have been obtained in Hyuga-nada and Sanriku region. Those studies show three important results : (1) the sites for co-seismic slip, episodic a-seismic slip, and continuous a-seismic slip do not overlap but complementarily share the plate boundary : (2) after-slip (post-seismic slip) may play an important role especially in the triggering large earthquakes : (3) the depth range of a-seismic slip may be controlled by not only a thermal effect but also some other factors such as lateral heterogeneity of fluidpressure and serpentinization.

著者

フローレス 慈英 松山 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.130, no.3, pp.353-368, 2021-06-25 (Released:2021-07-20)

参考文献数

32

被引用文献数

2

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Precipitation on the Ogasawara (Bonin) Islands from summer to autumn depends the intensity, frequency and tracks of tropical cyclones (TCs), which are affected by El Niño/La Niña events (EN/LN). This study is the first to investigate the seasonal variability of the ratio of TCs approaching the Ogasawara Islands to the total number of TCs generated, and to calculate the ratio of TC-induced precipitation to total precipitation during EN/LN TCs extracted from within 300 km of Chichi-jima by QGIS, when they are defined as “TCs approaching Chichi-jima”. Using precipitation at Chichi-jima Observation Station, TC-induced precipitation is calculated when a TC is within 500 km of Chichi-jima. From August to November, the ratio of TCs approaching the Ogasawara Islands to the total number of TCs generated over the Western North Pacific is highest in October. For the same period, the number of TCs approaching the Ogasawara Islands per year during EN is more than that during LN. Reflecting the anomaly of sea surface temperature, the genesis position of TCs during LN shifts westward. TC-induced precipitation on Chichi-jima from August to October during EN is larger than that during LN. in particular, in September, TC-induced precipitation during EN is 40 mm more than that during LN. The former accounts for 61% of the total precipitation in September. These phenomena are explained by the fact that the genesis position of TCs shifts eastward or south-eastward during EN, keeping the central pressure of TCs approaching Chichi-jima lower than that during LN. Also, the presence time of a typhoon from its genesis until it enters the 500 km range of Chichi-jima is longer in EN than in LN. Within the 500 km range of Chichi-jima, the central pressure of a TC is lower in EN than in LN. All these contribute to a large volume of TC-induced precipitation on Chichi-jima during EN.

著者

小原 一成

出版者

Tokyo Geographical Society

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.112, no.6, pp.837-849, 2003-12-25 (Released:2009-11-12)

参考文献数

20

被引用文献数

12 14

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Non-volcanic deep low-frequency tremors detected in southwest Japan are distributed in the forearc side along the strike of the descending Philippine Sea plate. The source depth of the tremor corresponds to the slab interface or the Moho discontinuity. The time sequence of the tremor activity is characterized by long durations from hours to weeks. The mobility and the successive occurrence of the tremor are thought to be related to the existence of fluid liberated from the slab by a dehydration process. The spatial distribution of the tremors is not homogeneous in a narrow belt but is spatially clustered. The major activity of the tremors with relatively long time durations is also clustered periodically, with a period of 2-3 months in the east and middle of Shikoku area and about 6 months in the west of Shikoku. On the other hand, tremors are sometimes triggered by local earthquakes or teleseismic waves. The periodicity of the tremor activity may represent a stable accumulation of fluid with a stable subduction process and the triggering phenomenon implies the unstable condition of the occurrence of tremors.

著者

齋藤 めぐみ 山田 和芳 スタッフ リチャード 中川 毅 米延 仁志 原口 強 竹村 恵二 ラムジー クリストファー Megumi SAITO-KATO Kazuyoshi YAMADA Richard A STAFF Takeshi NAKAGAWA Hitoshi YONENOBU Tsuyoshi HARAGUCHI Keiji TAKEMURA RAMSEY Christopher BRONK

出版者

東京地学協会

雑誌

地学雑誌 = Journal of geography (ISSN:0022135X)

巻号頁・発行日

vol.122, no.3, pp.493-501, 2013

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Sediment cores from Lake Suigetsu, Japan, reveal the absence of seawater intrusion into the lake caused by the historically documented tsunami of AD 1586 (Tensho Tsunami). A highprecision chronology of the cores established by Bayesian modeling radiocarbon determinations enables us to ascertain the precise position of the historical event in the sediment depth. Diatom analysis of the core shows that a diatom assemblage dominated by freshwater taxa persisted through the period. This makes a clear contrast with the core section around AD 1664 when the lake was artificially connected to the sea by a channel, and the subsequent intrusion of seawater was clearly recorded in the sediment cores by the occurrence of marine diatom fossils.

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.25, no.2, pp.146, 1913

著者

原 辰彦

出版者

Tokyo Geographical Society

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.114, no.3, pp.323-337, 2005-12-25 (Released:2009-11-12)

参考文献数

25

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We review seismological studies on structure of the Earth's deep interior. First, we describe spherically symmetric Earth structure and discuss its geophysical implications. Second, we show three-dimensional mantle structure revealed by seismic tomography and discuss its geophysical implications. Then, we briefly review various anomalous and interesting features found in the lower mantle and the inner core.

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.10, no.9, pp.510-511, 1898

著者

杉田 常吉

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.24, no.12, pp.845-852, 1912-12-15 (Released:2010-10-13)

著者

石原 舜三

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.1, pp.142-143, 1998-02-25 (Released:2009-11-12)

参考文献数

4

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極東ロシアのシホテリアンからチュコーツクに至る地域は, 西方のシベリア地塊 (先カンブリア紀基盤) の周辺に古生代以降の堆積岩類が発達し, 主に中生代中一後期に火山深成岩活動を伴う地質的背景を有し, 下記の様に多様な鉱物資源が発見されている。1) 原生代中期の地溝帯 : アノーソサイトに伴われるチタン鉄鉱-燐灰石鉱床 (P2O540億トン), 花崗岩に付随するREE, Nb-Ta鉱床など。2) 原生代最末期-カンブリア紀初期の地溝帯 : 層状Fe-Mn鉱床, 堆積性Pb-Zn鉱床など。3) オルドビス-シルル紀の融合-衝突帯 : 花崗岩に伴われるSn, F, Nb-Ta鉱床など。蛍石鉱床は大規模で鉱量4,500万トン (CaF2 32%) 。4) ジュラ紀中期の鉱化作用 : 花崗岩活動に関係する若干のAu, Bi鉱床。5) ジュラ紀後期-白亜紀初期鉱化作用 : 花歯岩と火山岩活動に関係するSn, W, Uなどのスカルン, 鉱脈型鉱床。Wスカルン鉱床が大きい。6) 白亜紀後期-古第三紀の鉱化作用 : 花歯岩と火山活動に関係するSn, W, Pb-Zn, Au-Ag鉱脈型, 一部スカルン及び鉱染型鉱床。カバレロボのSn鉱床は金属量34万トンでロシア最大。他にもコムソモリスク西方に数鉱床群。ダルネゴルスクのPb-Zn鉱床はPb-Zn金属量100万トンクラス。コリマーマガダン地域のデュカートAg鉱脈 (図1) はロシア最大の銀鉱山 (Ag金属量18,000トン, Au約50トン) 。金鉱床としてはナタルカ (図1) が大きく, Au約500トン, シホテアリンではアムール河口域のムノゴベルシンノエ鉱脈でAu金属量100トン以上。

著者

長沼 毅

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.122, no.2, pp.363-384, 2013

被引用文献数

2

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&emsp;The deep subsurface biosphere has been regarded as an emerging topic in geo-bioscience and industry for the past few decades, and has been approached by terrestrial and seafloor drillings. Terrestrial sites have better proximity and greater relevance to the anthroposphere and technosphere, <i>i.e.</i>, human habitats and societies, than do seafloor sites. Therefore, understanding the subterranean biosphere has more direct importance to issues related to a sustainable civilization, and issues such as formation/maturation of hydrocarbon reservoirs and ore deposits, disposal of radioactive wastes and carbon dioxide, and postulated association between seismogenic and microbial activities. Microbiological studies in the terrestrial deep subsurface have been prompted to respond to such human-related issues, and microbial life in sedimentary and crystalline rocks as well as pore-filling fluids has been studied to evaluate rock stability and (im) mobilization of redox-sensitive elements/nuclides, for instance. This is in contrast to subseafloor microbiology, which focuses more on microbial interactions with hydrothermal circulation, relevant biogeochemical processes including gas hydrate formation, associated diversity of life, and modern analogs of origin-of-life.<br>&emsp;Avoiding man-induced contamination of cored samples and pumped fluids has been a microbiological issue. Technical (both instrumental and operational) measures to minimize contamination were first developed in subterranean microbiology, because of easier accesses to test sites for repetition, evaluation, improvement, etc. of attempted measures on land. Then, anti-contamination expertise was introduced into subseafloor practices, and anti-contamination protocols and facilities are now better developed by the Integrated Ocean Drilling Program (IODP) than the International Continental Scientific Drilling Program (ICDP). Newly developed techniques are also applied to measure/monitor geological and geochemical parameters that are used to characterize microbial habitats and processes occurring there.<br>&emsp;Lessons from subterranean microbiology are directly applicable to subglacial microbiology that may retrieve microbial life from sub-million-year-old ice cores, although additional measures are needed for glacier drilling. Because land and icy surfaces are common in Earth-like planets or potentially life-bearing satellites, lessons (experiences and expertise) from subterranean microbiology should be applicable to astrobiological searches for extraterrestrial life.

著者

岩田 修二

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.89, no.6, pp.319-335, 1980

被引用文献数

15 9

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Movement types and intensity of surface processes were investigated on the slopes above the forest line of Mt. Shirouma-dake (2, 933 m. a. s. 1., 36&deg;45'N, 137&deg;45'E). The slopes studied are vegetation-free or sparsely vegetation covered ones that are mantled with rubble layers (thin layers of rock fragments).<BR>There are six types of slow mass movement operating on the rubble slopes talus creep, frost creep, needle ice creep, gelifluction, rapid solifluction, and a movement derived from snowpack creep. Rapid mass movement processes such as rockfalls, debris flows, and rolling down of stones often occur, but only a small amount of the materials is moved. Running water, supplied by rainfall and melting of snow and ground ice, carries the debris. While the amount of the materials moved by wash are not so large on the rubble slopes, the channel erosion is one of the important processes on the nivational rubble slopes that are covered by the long lasting snowpatches. The particle movement by wind and the transport in solution are probably insignificant on the study slopes.<BR>Relative vertical mass transfer in unit area that is a geomorphic work of process is estimated for a quantitative comparison of process intensity. The processes acting on the slopes are grouped as following five process sets according to their rates and types of the movements. I) Periglacial process set with low raet. II) Periglacial process set with medial rate. III) Nivational process set with low rate. IV) Nivational process set with medial rate. V) Nivational process set with high rate. The slow mass movements cover over 75 percent of the total mass transfer of the periglacial process set. The value of the slow mass movements of the nivational process set, however, is limited less than 75 percent of the total value and the remainder is mostly comprised in value of channel erosion. While the periglacial process sets occur on the periglacial rubble slopes that are put under the snow free dry conditions throughout the year, the nivational process sets occur on the nivational rubble slopes. The rate of these process sets vary according to the differences of the climatic environments, slope forms and gradients, and slope materials ; size of the surface material and thickness of the rubble layer. Among them the slope materials perform the important role. The process sets with low rate (less than 3.0&times; 10<SUP>3</SUP>m&middot; t/ Km<SUP>2</SUP>&middot;yr.) correspond with the processes occurring on the slopes which are mantled by the boulder size debris. The process sets with high rate (over 6.0 &times; 10<SUP>3</SUP>m&middot;t/ Km<SUP>2</SUP>&middot;yr.) occur both on the nivational slope with steep gradients and the nivational slopes covered by fine materials.

著者

鶴我 隹代子 小川 克郎 長尾 大道 羽佐田 葉子 藤井 直之 笠原 順三 熊澤 峰夫

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.114, no.4, pp.659-664, 2005-12-25

参考文献数

6

著者

飯山 敏道

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.96, no.5, pp.309-311, 1987

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日本学術会議地質学研究連絡委員会は, 1982年いらい国際地質学会議 (IGC) を1992年に日本で開催することについて, その学問的・社会的意義とその可能性などを検討する小委員会を設け, 審議をかさねました。その結果, IGCはその開催方式や内容をいままでのIGCの慣例に固執することなく, 日本独自の方式を開拓し, 準備を周到におこなえば, 技術的にも可能であり, 意義深いものにすることができるとの結論に達しました。そこで, 1984年モスクワのIGCにおいて, 日て本誘致を提案いたしました。このとき, 中華人民共和国も誘致を提案したため, 1985年2月に, IUGS・IGC共催のSteering Committeeは, 1992年日本開催に同意し, 1996年中国での開催を勧告いたしたした。正式には1989年のワシントンのIGCで決まることですが, 1985年4月IGC検討小委員会は発展的に解散し, 地質学関連の大学・官庁・企業から派遣された委員によって, 日本学術会議からは独立したIGC準備委員会が発足いたしたした。この委員会は1989年ワシントンで開催される第28回IGCにおいて, 日本開催が正式に決定され, IGC組織委員会が発足するまで機能し, 準備を整える役割をもっています。正式承認まえの準備会であるため, 公的な機能をもつことができませんが, 準備委員会内に設けられた総務・プログラム・巡検・会場・経理・出版の各小委員会が準備を進めておりますので, ここに, 活動状況を報告します。正式承認後開催まで3年の歳月しかありません。準備委員会は可能なかぎり準備を整えて1989年に発足するはずの組織委員会に引き継ぎたいと考えています。準備委員会の活動に御意見をお寄せくださるなど, 各位の絶大なる御協力をお願いいたします。

著者

岩崎 重三

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.43, no.7, pp.424a, 1931

著者

財城 真寿美 三上 岳彦

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.122, no.6, pp.1010-1019, 2013

被引用文献数

6

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&emsp;Climate variations in Tokyo based on reconstructed summer temperatures since the 18th century and instrumental meteorological data from the 19th century to the present are discussed. During the Little Ice Age, especially in the 18th century, remarkably cool episodes occurred in the 1730s, 1780s and 1830s. These cool conditions could be a significant reason for severe famines that occurred during the Edo period. Around the 1840s and 1850s near the end of the Edo period, it was comparatively warm which could correspond to the end of the Little Ice Age in Japan. Although there was a low-temperature period in the 1900s, a long-term warming trend could be seen especially in winter temperatures and daily minimum temperatures throughout the 20th century. While annual precipitation has been increasing during the last 30 years, relative humidity has been decreasing. This could result from a saturated vapor pressure rise due to warming and from a loss of water bodies due to urbanization. During the last century, not only warmer conditions but also wetter conditions in summer and autumn and drier conditions in winter and spring were documented by analyzing hythergraphs.

著者

吉田 明夫 外谷 健 吉田 真希子

出版者

Tokyo Geographical Society

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.113, no.1, pp.107-124, 2004-02-25 (Released:2009-11-12)

参考文献数

39

被引用文献数

1 1

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We investigated solar-cycle and semiannual variations of magnetic storms based on data observed at the Kakioka Magnetic Observatory since 1924. First, we show that magnetic storms with a peak value of ≥ 100 nT are considered to have been almost completely recorded for both types of storm, i.e., those with sudden commencement (Ssc) and those with gradual commencement (Sg). Using data for storms larger than 100 nT, we found that the variation of numbers of Ssc correlates well with that of the sunspot Wolf numbers, but that of Sg does not. The number of storms decreases linearly with the peak value in the semi-logarithmic plot. The inclination is steeper for Sg storms than for Ssc storms. The semiannual variation, that is, more storms are observed in spring and fall than in summer and winter, is clearly seen for storms with a peak value ≥ 100 nT for Sg, but it is recognized only for larger storms with a peak value ≥. 150 nT for Ssc. Concordant with the difference between Ssc and Sg in the semiannual variation, the decrease in the number of large storms in the semi-logarithmic plot is less in spring and fall than that in summer and winter for Ssc. Although such a difference is not apparently seen for Sg, the ratio of the number of storms with a peak value ≥ 150 nT to that of storms with a peak value between 100 nT and 150 nT is larger for spring and fall. We propose the hypothesis that the efficiency of magnetic reconnection depends on the three dimensional direction of the magnetic field in the solar wind relative to the geomagnetic field, and on the north-south symmetry of the geomagnetosphere when it is seen from the stream of the solar wind. We think these “equinoctial effects” are the main causes of the semiannual variation in the number of large magnetic storms. As for the Sudden Commencement (SC), the semiannual variation is not seen, but an annual variation with the number of SC being larger in summer is observed. The reason may be that the shock wave in the solar wind hits against the northern part of the geomagnetosphere in summer, and the southern part in winter.

出版者

Tokyo Geographical Society

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.27, no.2, pp.184a-185, 1915

著者

駒澤 正夫 ホセ パンティーク エディー リスタンコ

出版者

Tokyo Geographical Society

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.123, no.1, pp.133-142, 2014

被引用文献数

3

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イロシンカルデラの地下構造を把握するため1996年2月にBulusan火山およびその周辺で重力調査を実施した。測点は標高の低い山麓の道沿いに限られ,測定数は225点となった。火山の山体に近い密度である 2,300 kg/m³(2.3 g/cm³)の仮定密度のブーゲー異常図は,山体部に測点がなくても実際の重力異常を表すと考えられる。重力異常にはカルデラ壁に対応する急勾配がBulusan火山の東から南を経て西に存在することがわかった。しかし,カルデラの北縁については勾配構造が明瞭ではなかった。Irosin townは急勾配構造の内側にある低重力異常域にある。重力の3次元解析から得られた重力基盤にはカルデラ壁を含むカルデラ領域を示す直径 15 kmほどの円形構造があることがわかった。さらに,その円形構造の内側には直径 5 kmほどの急勾配の壁で仕切られた漏斗状(上下逆さまの円錐)の構造が存在し,深さは 1.5 kmに達することがわかった。つまり,イロシンカルデラは,陥没構造が一カ所だけ確認でき,大量の火山砕屑物の噴出を伴った大規模噴火(複数回の場合も含む)は,ごく狭い領域に限られることを示している。また,重力異常による質量欠損の計算から約 40 km³の領域から1.1 × 10¹⁰ トンの火山砕屑物を噴出したと推定され,既存のカルデラの直径と質量欠損の関係と整合的である。

著者

池上 隆

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.26, no.3, pp.181-191_2, 1914-03-17 (Released:2010-10-13)

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.16, no.4, pp.278-279, 1904