地学雑誌
Online ISSN : 1884-0884
Print ISSN : 0022-135X
ISSN-L : 0022-135X
108 巻 , 5 号
選択された号の論文の17件中1~17を表示しています
  • 小出 良幸
    1999 年 108 巻 5 号 p. 509-536
    発行日: 1999/10/25
    公開日: 2009/11/12
    ジャーナル フリー
    Recently, some new scientific results on the origin of life have been reported. They have led to important discussions on the nature of life. Life, in this paper, means all living existence, which includes terrestrial, extra-terrestrial, present, and fossil organisms. A wide range of scientific fields such as astronomy, planetary science, meteoritic science, geology (paleontology), organic synthetic science, and terrestrial biology should reveal the origins of life. I extracted research results on the origins of life in these fields, and reviewed them.
  • 平野 昌繁, 橘 菊生, 長谷川 博幸
    1999 年 108 巻 5 号 p. 537-551
    発行日: 1999/10/25
    公開日: 2009/11/12
    ジャーナル フリー
    Caissons bounding fill-lands were displaced largely by the 1995 Hyogoken-nanbu earthquake. The direction and amount of lateral (seaward) bulging of the caissons along the north-western Osaka bay were obtained by photogrammetry of surface targets from Ashiya-hama to Nada-hama with an accuracy of less than 10 cm for the horizontal displacement. The displacement vectors show a definite and systematic drift form the outward normal to the shore line, and the drift is explained by the superposition of the regional tectonic movement on the original lateral movement. The tectonic vector was so obtained that shearing components along a given set of caissons are given simultaneously. The tectonic movement obtained is SW-directed at the south-east side and NE-directed at the north-west side of the south-western extension of the Koyo fault recognized in the Rokko and traced by right-lateral off-sets by the earthquake. Direction and magnitude of the detected tectonic vector are in harmony with that given by the systematic displacement of the piers supporting the Hanshin Expressway (Route 5) at the south-eastern side of the fault. The amount of the tectonic vectors ranges from 20 cm to 40 cm. Changes of the amount due to the distance from the fault gives the fault parameters based on the dislocation model for strike-slip fault, and the fault from 3 km to almost 0.1 km in depth with the right lateral off-set of 1.6 m can bring the displacement field obtained here at the water-front. Nevertheless, further precise measurement and investigation are required for a more exact determination of the fault parameters.
  • 景山 陽一, 西田 眞, 肥田 登
    1999 年 108 巻 5 号 p. 552-561
    発行日: 1999/10/25
    公開日: 2009/11/12
    ジャーナル フリー
    アマゾン低地のような広域を対象とする場合, 衛星データを用いたモニタリングが一般的とされる。しかし, 受動センサであるランドサット5号のThematic Mapper (TM) センサにより取得された画像データ (以下, TMデータと略記する) は雲の影響を受けやすく, 雲量の多いアマゾン川流域で利用可能な複数のデータの入手は困難といった問題点を有していた。一方, JERS-1の Synthetic Aperture Radar (SAR) は気象条件・昼夜に関係なく地表を観測できるとともに, 地上分解能の高い画像データ (以下, SARデータと略記する) を取得できるため, 時系列的に地球環境のモニタリングを行なう一手段として期待されている。しかし, TMデータは測定波長域の異なる計7バンドのマルチスペクトル情報を有しているため, 土地被覆分類が比較的容易であるのに対し, SARデータは単一輝度レベル情報を有しているにすぎない。従って, 一時期に取得したSARデータから詳細な土地被覆分類を行なうことは, TMデータと比較し困難である。しかしながら, 多時期に取得された複数のSARデータを用いて解析を行なう場合でも, データ取得時における土地被覆物の特性を解析し, 詳細な土地被覆状況を把握することは必要不可欠であると思われる。
    そこで本研究では, 分解能 (18m) の高いSARデータにおいて, 土地被覆状況の相違を表し得る局所フラクタル次元を用い, アマゾン川中下流域における水域推定を行なった。さらにSARデータおよびランドサットTMデータの輝度レベル情報を用いた分類結果との比較検討も試みた。その結果, SARデータの局所フラクタル次元および輝度レベル情報のどちらを用いた場合でも水質状況の判別は困難であったものの, 局所フラクタル次元を用いることにより, データ取得時の細かな土地被覆状況を再現できることを明らかにした。なお, 今回使用したSARデータとランドサットTMデータは取得時期が異なるため, 推定結果に明確な一致は認められなかったものの, SARデータの局所フラクタル次元を用いた推定結果と現地調査により得られた知見との間に矛盾点はなく, むしろ良好な対応が得られた。また, SARデータの局所フラクタル次元を用いて解析を行なった結果, 対象地域の水域は約34.2%と推定された。
  • 杉村 新, 斉藤 勝, 東郷 正美, 池田 安隆, 蟹江 康光, 江藤 哲人, 太田 陽子, 佐藤 比呂志, 浅見 茂雄, 藤井 義仁
    1999 年 108 巻 5 号 p. 562-588
    発行日: 1999/10/25
    公開日: 2009/11/12
    ジャーナル フリー
    The Kitatake fault is the major fault of Kitatake fault zone, WNW-ESE striking across the Miura Peninsula, south of Tokyo. The Kitatake fault zone is almost parallel to Kinugasa fault zone (north) and to Takeyama fault zone (south). All of these fault zones are active and show right-lateral slips inferred from geomorphic features. The eastern half of the Kitatake fault delineates the boundary between Zushi Formation (Late Miocene) in the north and Hayama Group (EarlyMiddle Miocene) in the south and shows south-facing scarps probably owing to the resistant Zushi Formation.
    We carried out observations in 1994 and dating in 1995 with three trenches, one being 9 meters deep, on the unconsolidated Holocene sediments along the Kitatake fault. We obtained 36 dates from 33 samples.
    The latest episodic slip along the fault seems to have ocurred at about 1, 440 yBP (14C), that is A.D. 600650. The ratio of the horizontal component with the vertical one may be about 2.04.2. The amount of the latest episodic slip is not certain, but might be in the order of meters.
    Another episodic slip prior to the latest one probably occurred at least before 3, 070 yBP ( 14C).
  • 豊蔵 勇, 岡田 篤正, 牧野内 猛, 堀川 義夫, 長谷川 淳
    1999 年 108 巻 5 号 p. 589-615
    発行日: 1999/10/25
    公開日: 2009/11/12
    ジャーナル フリー
    Construction of the Chubu International Airport has started off Tokoname City (Chita Peninsula) in Ise Bay. Various surveys such as bathymetry, seafloor drilling, sonic prospecting, and geologic examinations of recovered borehole core samples, have been performed to reveal soil engineering characteristics, submarine topography, and submarine geology at the airport site (Chubu Kuukou Chousakai=The Chubu International Airport Research Foundation, 1994). Many fruitful results on the submarine geology have been obtained in these surveys, as follows :
    (1) The submarine topography is divided into the inshore “Upper submarine terrace”, “Offshore gently sloping sea floor”, and “Submarine scarp” between the two. A submarine channel is trenched southwards on the inshore submarine terrace.
    (2) The bay area is underlain by the A, B, C1, C2, and T Formations, in descending order. The T Formation is Mio-Pliocene Tokoname Group, the basement of the bay area. The Tokoname Group forms a buried wave-cut platform of a peninsular shape, which extends southwards. On the east side of the peninsular wave-cut platform, a submarine buried valley stretches southwards under the submarine channel and is mostly filled with the A Formation. On the west side of the wave-cut platform runs the Ise Bay Fault, and the A, B, C1, and C2 Formations thicken offshore.
    (3) The A Formation, which is divided into the A1 (upper), A2 (middle), and A3 (lower) Members, consists of marine muddy strata of the present bottom surface and is correlated with the Nanyo Formation below the Nohbi Plain (north of the Ise Bay). The A Formation is 25 to 35 meters thick, and the 14C ages range from 9, 400 to 5, 200 y. B.P. of Holocene age.The A3 and A2 Member intercalates the U-Oki and K-Ah tephra, respectively, both are widespread tephra layers in Japan.
    (4) The B Formation, which is divided into the B1 (upper), B2 (middle), B3 (lower), and B4 (base) Members, consists of sand beds and gravelly beds. The B1, B2, and B3 Members are correlated with the Nohbi and First Gravel Formations below the Nohbi Plain, respectively. The B4 Member forms a buried terrace on the west slope of the peninsular wave-cut platform and is correlated with the Toriimatsu or Ohzone Formations, Lower Terrace Deposits in the eastern margin of the Nohbi Plain. The B Formation is of late Pleistocene age.
    (5) The C1 Formation consists mainly of marine clay beds about 40 meters thick. The fossil pollen composition indicates that the C1 Formation is correlated with the lower part of the Atsuta Formation in the Nohbi Plain and is of middle Pleistocene age.
    (6) The C2 Formation consists of sand (upper) and gravelly (lower) beds and exceeds 50 meters thick. The fossil pollen composition indicates that the C2 Formation is correlated with the Ama Formation below the Nohbi Plain and is of middle Pleistocene age.
    (7) The basement T Formation (Tokoname Group) consists of alternating sand and compact mud beds and intercalates two volcanic ash layers, which are correlated with the Souri (upper, Sr) and Higashitani (lower, Hg) Volcanic Ash Layers from the conformity in index of volcanic glass. The Souri and Higashitani V. A. Ls are intercalated within the upper horizon of the Tokoname Group in the Chita Peninsula.
    (8) The Ise Bay Fault (faults and flexure zone), trending in the NNW-SSE direction, extends in the western margin of the bay area. The Tokoname Group on the east side of the fault trends northwest and gently dips northeast. The Utsumi Fault, trending in the WNW-ESE dircction, extends in the southern margin of the peninsula.
    The geological relationship between the Chita Peninsula and airport site in the above-mentioned results brings the following problems for further study.
  • 中村 有吾, 平川 一臣, 長沼 孝
    1999 年 108 巻 5 号 p. 616-628
    発行日: 1999/10/25
    公開日: 2009/11/12
    ジャーナル フリー
    Eleven marker tephras were found at and around a famous paleolithic site in the Shirataki Basin, eastern Hokkaido. The following conclusions are the result mainly of a petrographic analysis, i.e., ratio of glass and minerals, composition of heavy minerals, shape of volcanic glass, and refractive indices of glass, orthopyroxene and hornblende.
    1) Three widespread tephras were identified in the Shirataki Basin; Tarumae-a pumice (Ta-a) that erupted from Tarumae volcano, western Hokkaido at 1739AD, Kussharo-Shoro ash (Kc-Sr) that erupted from the Kussharo caldera, eastern Hokkaido at ca. 32ka, and Shikotsu-1 pumice (Spfa-1) that erupted from the Shikotsu caldera, western Hokkaido at ca. 40 ka.
    2) Shirataki-1 pumice (Sit1) is identified with Daisetsu-Ohachidaira pumice (Ds-Oh). Ds-Oh erupted from Daisetsu volcano, central Hokkaido, prior to the eruption of a large pyroclastic flow associated with the formation of the Ohachidaira caldera at ca. 30 ka. Sit1 =Ds-Oh spread widely in the Shirataki Basin and shows a horizon just below the Shirataki stone implements. Thus Ds-Oh must be an important key bed for correlating and chronologically arranging paleolithic cultures in the eastern Hokkaido.
    3) Shirataki-5 pumice (Sit5) overlies the middle terrace surface in the Shirataki Basin. Sit5 is identified with Toetoko ash (TT) distributed around Lake Saroma. On the basis of stratigraphy by means of pyroclastic flow deposits from the Kussharo caldera and palynological evidence, Sit5=TT seems to be dated back to 150-200 ka. Sit5 is probably distributed in the wide area of the Okhotsk region of Hokkaido. Although the source vent has not been determined yet, Sit5 should be a valuable marker tephra indicating the Middle Pleistocene.
  • 石井 正樹, 小疇 尚
    1999 年 108 巻 5 号 p. 629-637
    発行日: 1999/10/25
    公開日: 2009/11/12
    ジャーナル フリー
    A number of collapses, landslides, and debris flows occurred in the Himekawa river basin, in the northeastern part of the Japanese Alps, caused by an intense rainstorm (814 mm/2 days) on 11 and 12 July 1995 after the long periods of rainfall. A debris flow induced by failures of late glacial moraines at thresholds of two cirques traveled down into the Shirouma-daisekkei valley, a tributary of the Himekawa river in the midst of the rainstorm. The debris flow deposits (2, 200 m in length, 80 m100 m in width, 2.5×104 m3 in volume), covered the large snowpatch remaining on the valley bottom, and a longitudinal trench was formed at the center of the snow patch by debris flow. The moraines had been saturated with a large quantity of precipitation during the rainy season and snow meltwater in early summer, followed by the large volume of water of the rainstorm. Consequently, a voluminous discharge concentrated on the cirque floors, and rushed out to the moraines of the cirques, causing their collpse. The frequency of such an intense rainstorm in the area is considered to be once in two hundred years, therefore, the volume of moraine failures induced by intense rainstorms can be estimated to be more than 1×106 m3 during the Post Glacial period. This kind of moraine failure plays an important role in the degrading processes of Pleistocene glacial landforms located in the upstream of the glaciated valleys in Japan, because of its rainy and snowy climatic characteristics.
  • 水谷 伸治郎
    1999 年 108 巻 5 号 p. 638
    発行日: 1999/10/25
    公開日: 2009/11/12
    ジャーナル フリー
  • 近藤 昭彦
    1999 年 108 巻 5 号 p. 639
    発行日: 1999/10/25
    公開日: 2009/11/12
    ジャーナル フリー
  • 1999 年 108 巻 5 号 p. 640
    発行日: 1999/10/25
    公開日: 2009/11/12
    ジャーナル フリー
  • 1999 年 108 巻 5 号 p. 640a
    発行日: 1999/10/25
    公開日: 2009/11/12
    ジャーナル フリー
  • 1999 年 108 巻 5 号 p. 640b
    発行日: 1999/10/25
    公開日: 2009/11/12
    ジャーナル フリー
  • 磯崎 行雄
    1999 年 108 巻 5 号 p. 643-649
    発行日: 1999/10/25
    公開日: 2009/11/12
    ジャーナル フリー
  • 石井 正樹
    1999 年 108 巻 5 号 p. Plate1-Plate2
    発行日: 1999/10/25
    公開日: 2009/11/12
    ジャーナル フリー
  • 石井 正樹, 小疇 尚
    1999 年 108 巻 5 号 p. Plate3-Plate4
    発行日: 1999/10/25
    公開日: 2009/11/12
    ジャーナル フリー
  • 杉村 新, 斉藤 勝, 東郷 正美, 池田 安隆, 蟹江 康光, 江藤 哲人, 太田 陽子, 佐藤 比呂志, 浅見 茂雄, 藤井 義仁
    1999 年 108 巻 5 号 p. Plate5-Plate7
    発行日: 1999/10/25
    公開日: 2009/11/12
    ジャーナル フリー
  • 磯崎 行雄
    1999 年 108 巻 5 号 p. Plate8
    発行日: 1999/10/25
    公開日: 2009/11/12
    ジャーナル フリー
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