地学雑誌
Online ISSN : 1884-0884
Print ISSN : 0022-135X
ISSN-L : 0022-135X
80 巻 , 3 号
選択された号の論文の7件中1~7を表示しています
  • 田嶋 久
    1971 年 80 巻 3 号 p. 133-159
    発行日: 1971/06/25
    公開日: 2009/11/12
    ジャーナル フリー
    One of the most striking aspects of the movement of population in Peru is the migration from Andes highland the “Sierra” to the coastal region.
    In the Sierra of Central Andes of Peru, there are many indian peoples, living on self-sufficient agriculture. The great number of them moves to the coastal region.
    The traditional safety value for the surplus population of the Sierra has been the irrigated oasis of the desert coast. But in few decades migration from the Sierra has far exceeded the absorptive capacity of the coastal plantation, and has been directed increasingly toward the coastal cities particularly Lima, capital of this country.
    Major concentrations of the population occur around Lima city. They come from the whole country not only from Andes highland, but also from the coastal region. The slums that ring the capital city are conclusive evidence that the urban habitant is incapable of accommodating the surplus population.
    The altitudinal point of view, the surplus population at the elevation higher than 2, 500 m moves to the coastal region lower than 1, 500 m, but yet population of highland are increasing slowly.
    The smaller though significant, movement has been taking place from the Sierra to the upper tropical Amazonas region, “Selva” lower than 1, 500 m. The main concentrating region of population are Lima, Callas, other coastal cities (Trujillo, Chiclays, Chimbote, Arequipa) and small cities in central region of Andes highland.
    On the contrary, the main emigrating region are Andes highland and the most of the coastal cities. From the coastal cities, many people migrate to Lima, but from the Sierra near by, surplus population flow to these cities, and the population of these cities has been increasing.
  • 水谷 武司
    1971 年 80 巻 3 号 p. 160-178
    発行日: 1971/06/25
    公開日: 2009/11/12
    ジャーナル フリー
    The mechanism of slope erosion and the process of slope formation have been studied by physical and morphometrical analysis.
    In the previous study, a fundamental equation on slope erosion
    E=Klm (sinθ-sinθc) n (1)
    E : erosion depth at l
    l : distance from the top of the slope
    θ : slope angle k, m, n, θc : constant was derived by hydrological and physical considerations of erosional agents such as tracting force of flowing water and abrasion due to material of mass movement. Theoretical values of erosion depth obtained from equation (1) agree quite well with measured values at youthfully dissected strato-volcanoes in Japan.
    In the present paper, erosional landforms of several strato-volcanoes in the stage of early maturity were measured and averaged profiles of initial and present landforms and altitudinal changes of average amount of erosion depth were obtained. Multiple regression coefficients log K, m and n were obtained with each slope by the method of least squares. The values of m and n are nearly 1 at most of slopes out of relation to location, erosional stage and scale of the slope. Theoretical values of erosion depth calculated from equation (1) with determined coefficients have also good agreements with measured values at these fairly highly dissected volcanoes.
    The amounts of undercutting of valley beds at volcanoes are also given by equation (1). Theoretical basis of this agreement was obtained by physical consideration of erosional processes.
    Equation (1) was derived supposing uniform sheet erosion all over the slope. This supposition, however, does not hold at highly dissected slope. The reason of applicability of equation (1) to highly dissected volcanoes can be explained by assumptions that erosional process at valley bed is dominating and the recession of valley wall proceeds in proportion to the amount of undercutting of valley bed keeping the gradient of slope almost constant.
    Equation (1) can also be applied with success to the process of slope formation of abandoned coal slag heaps which are dissected by gullies. Thus, applicability of equation (1) to some of non-volcanic slopes was ascertained.
    Gradient of the lower end of the slope where radial valleys nearly disappear decreases as dissection of the slope precedes. Then, θc is not a constant but a function of E.
    Gradient and curvature of slope are thought to be regulating factors of slope erosion.However, multiple regression coefficients of these terms are entirely insignificant at several slopes. Gradient and curvature of slope are infered to be local and temporary factors.
    From modifying equation (1), the following equation of slope development is derived,
    ∂y/∂t=f1 (x, y) xm {∂y/∂x+g (t)} +f2∂y/∂x
    General process of slope development have been studied by solving the equation under various initial conditions.
  • 諏訪 彰
    1971 年 80 巻 3 号 p. 179-182
    発行日: 1971/06/25
    公開日: 2009/11/12
    ジャーナル フリー
    関東南部の震災対策・異常地殻変動など, 地震に対する官民の関心がにわかに高まつている折から, 2月9日朝6時 (日本では夜23時) 1 分頃, ロサンゼルス市を襲つた地震は, 近代都市の地震対策を進めるために, 他山の石として, 学ぶべきことが実に多い。1906年のサンフランシスコ地震は, 米国内はもとより日本などでも, 地震学・地震工学を画期的に促進したが, 今回の地震も同様な効果をおよぼすだけでなく, 地震に対するより広範な防災体制の整備への契機にもなり得よう。
    この地震のP波が, 約9,000kmを隔てた松代の気象庁地震観測所の地震計に記録されたのは, 地震が発生してから約12分後のことであつたが, 日本の放送や新聞がこの震災を報じ始めたのは, 翌10日の朝からである。そして, 建設省を主軸とする政府合同調査団や東京・神奈川・大阪・横浜・川崎・名古屋・神戸などの都県市の調査団が相ついで現地へ派遣された。民間土建業者や報道関係者などを加えると, この地震のために日本から現地へ派遣された者は100名余を算した。
    筆者も, 政府合同調査団の唯一の地学専門家として, 2月21日~3.月4日, 現地を踏査するとともに, カリフォルニア州内の関係諸機関を歴訪し, 今回の地震の実態, 災害状況, 観測研究体制, 地震情報の作成・発令・伝達状況などをつぶさに調査してきた。
    この地震は, 死者62名, 傷者1,000余名を出し, 家屋・病院・学校・ダム・高速道路・変電所・ガス・水道などに惨害をもたらした。全壊ないし立入り禁止の建物は821棟を算し, また, バンノーマン・ダムが決潰にひんしたため, 一時は約8万名の住民が緊急避難した。しかし, この災害状況や防災活動については, かなりよく報道されているので, ここでは, 地学関係の事項に限つて報告する。
  • Lowell J. DAVID
    1971 年 80 巻 3 号 p. 183-191
    発行日: 1971/06/25
    公開日: 2010/04/23
    ジャーナル フリー
  • 保柳 睦美
    1971 年 80 巻 3 号 p. 192-194
    発行日: 1971/06/25
    公開日: 2009/11/12
    ジャーナル フリー
  • 1971 年 80 巻 3 号 p. 196
    発行日: 1971年
    公開日: 2009/11/12
    ジャーナル フリー
  • 荒牧 重雄
    1971 年 80 巻 3 号 p. Plate1-Plate2
    発行日: 1971/06/25
    公開日: 2009/11/12
    ジャーナル フリー
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