著者

湯村 哲男 広野 卓蔵 和達 清夫

出版者

公益社団法人 日本地震学会

雑誌

地震 第2輯 (ISSN:00371114)

巻号頁・発行日

vol.23, no.2, pp.99-121, 1970

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Spatial distribution of earthquake foci for the period from 1926 to 1968 in and near Japan were expressed in 16 maps each for a layer of 20-40km in thickness lying between 0 to 600km in depth. The maps show definitely the boundary lines and centers of local activities distinguishable in seismicity from each other. We named them seismic blocks. The centers of the shallow seismic blocks which crowd in a zone along the west side of the Japan trench can be traced down to 600km in depth. At first such centers move with increasing depth toward two junction areas of the island arcs of Kuril, NE-Japan and Izu-Bonin, that is, the Hokkaido and the Kwanto districts. From there they continue sinking to north for Hokkaido and to west for Kwanto making a dipping angle of 30°. Then their directions change abruptly by 90° at a depth of about 300km. From North Hokkaido one branch of the locus of the center goes into the Okhotsk Sea and the other into the Japan Sea along the coast of Primorye. On the other hand, the locus of the block center moving toward the west Kwanto turns to the south at that depth under Gifu Pref. for the Shikoku Basin, although a shorter branch goes northward into the Japan Sea. It is notable that few deep shocks occur in the middle of the Japan Sea. Considering the other geophysical and geological phenomena such as (1) the negative zone of isostatic anomaly of gravity lying along the Japan trench branches out to the junction areas in land, (2) the movement of the triangulation stations for the last 60 years or so amounts to about 3m to the north at Aomori Pref. in comparison with the Kui Peninsula, showing that two forces are acting in the respective areas in opposite directions, (3) the axis of mountain ranges made of metamorphic rocks which encounter the locus of the block center in Hokkaido and Central Honshu underwent severer bending, we conclude that the locus of the seismic block center expresses the location of the mantle current coming from the Pacific. itself.

著者

和達 清夫

出版者

公益社団法人 日本地震学会

雑誌

地震 第2輯 (ISSN:00371114)

巻号頁・発行日

vol.4, no.5, pp.265-270, 1932

著者

和達 清夫

出版者

東京帝国大学

巻号頁・発行日

1932

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博士論文

著者

和達 清夫

出版者

公益社団法人 日本気象学会

雑誌

気象集誌. 第2輯 (ISSN:00261165)

巻号頁・発行日

vol.15, no.8, pp.295-316, 1937

被引用文献数

1

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In the present paper are treated the problems concerning the mechanism of earthquakes from the stand point of the seismological observation of earthquake waves. First of all the importance of generation of a fault is discussed for the occurrence of earthquakes. Then the fact so-called &ldquo;quadrant distribution of first motion&rdquo; which is observed in almost all cases of earthquakes of both shallow and deep origins can be considered as a naturally expected phenomenon if earthquakes occur first in the crust by breaking, in other words by fault, and the conservation of angular momentum be hold. Hitherto, oscillators are sometimes considered at the source of earthquakes to interpret the distribution of the first motion, such as &ldquo;center of compression or dilatation&rdquo; &ldquo;doublet with moment&rdquo; or &ldquo;a pair of doublet with (without) moment&rdquo; etc. Yet we have perhaps never heard of the simple explanation mentioned above that the distribution of the first motion can be interpreted by the motion caused by a doublet (with moment) and adding to it by that of the opposite sign caused by the reaction of the former.<br>Although the first motion of earthquakes can be considered to be caused by a pair of doublet oscillator, it is quite another phenomenon as to the crustal deformation observed in the epicentral region where sometimes a remarkable fault may be found in the case of large earthquakes. The latter phenomenon cannot be satisfactorily interpreted by the assumption that a pair of doublet nuclei of force act in the crust, but rather explained by the assumption that there exists only one doublet nuclei of force in the crust, each of them lies on each side of the fault surface in a certain depth.<br>A trial is made to obtain mathematically the crustal deformation at the surface occurred near the fault by a great earthquake. For the simplest case, the following assumptions are made. In a semi-infinite elastic body, surface. being <i>z</i>=0, the fault surface <i>y</i>=0 and <i>z</i> axis taken positive downwards, a nucleus of force exists at (0, -<i>b, b</i>.) and a force <i>X</i>₀ acts horizontally to <i>x</i>-direction, another nucleus at (0, -<i>b, b</i>), force acts there -<i>X</i>₀. As boundary conditions, stress must be vanish at <i>z</i>=0 and also at the fault surface <i>y</i>=0. The method used for this calculation is similar to that made by F. I. W. Whipple (M. N. of R. A. S. Geo. Sup. Vol. 3, No.6) and the approximate solutions obtained. The crustal deformation thus obtained resembles much to that actually observed.<br>In the last part, the problem of the wave propagation of shallow earthquakes is treated. Dr. H. Nakano treated theoretically this problem assuming oscillators in a general form at the origin. Dr. H. Honda proved that the actually observed result of seismic waves agrees just well with a special case of this theoretical result. Of couse this proof is good in general tendency but if we examine precisely the observed result, it may be found that the problem of propagation of seismic waves issued from a very shallow origin can not be treated under such a simple conditions as assumed by Dr. Nakano that the medium is uniform and perfect elastic and the origin lies just on the surface. He obtained that the amplitude of solid seismic waves decreases with epicentral distance as <i>A_P</i>&prop;&Delta;^-2, <i>A_T</i>&prop;^-1 in their principal directions respectively, and this theoretial result ascertained by Dr. Honda using many observational data. But in the practical case, the earth's crust is not homogeneous, the seismic-focus does not lie strictly on the surface and therefore the conditions of wave propagation must be somewhat different from this theoretical result.

著者

和達 清夫 安倍 北夫 檀原 毅 中野 尊正 松田 磐余 望月 利男 国井 隆弘

出版者

東京都立大学都市研究センター

雑誌

総合都市研究 (ISSN:03863506)

巻号頁・発行日

no.5, pp.91-102, 1978

著者

和達 清夫 高橋 末雄

出版者

公益社団法人 日本地震学会

雑誌

地震 第2輯 (ISSN:00371114)

巻号頁・発行日

vol.27, no.1, pp.42-56, 1974

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In the present paper the underground structure peculiar to Japan and its neighborhood is dealt with, based on the seismic activity in Japan and neighborhood, especially taking account of the fact that each of the seismic activity area and the seismic inactivity area shows in the subterranean space its respective space, and adding the authors' investigational result to the fruits of researches hitherto.<br>Main results of the present paper are:<br>(1) The seismic activity area was divided into 3 zones: the shallow earthquake zone (particularly the existence of &ldquo;a thick shallow earthquake zone&rdquo;), the joint earthquake zone and the deep earthquake zone.<br>(2) A concept that the seismic activity zone can be regarded as &ldquo;the crust&rdquo; has been proposed.<br>(3) From the discussion of the travel time residual and the area of abnormal distribution of seismic intensities, the values of Low <i>V</i> and Low <i>Q</i> of the seismic inactivity area were obtained, and in particular the stronger point of that property was found at a comparatively small depth in the underground on the continental side along the volcanic front.<br>(4) The mantle flow in Japan and neighborhood is assumed to be composed of its main flow (along the deep earthquake zone) which flows descending from the Pacific side to the continental side and from east to west, of a weak flow northward in the offing of Tosa and in Enshu-nada, and of flows eastward and southward from the direction of the Sea of Japan.<br>(5) In general, where the mantle flow ascends, there exist Low <i>V</i> and Low <i>Q</i> and the area is related to volcanic activities, and where the flow descends, the area is related to the seismic activity area.<br>(6) The joint earthquake zone is an area of the strongest seismic activity, and is closely related with large-scale earthquakes.

著者

和達 清夫 荒川 秀俊

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.63, no.3, pp.117-121, 1954

著者

和達 清夫 川瀬 二郎

出版者

公益社団法人 日本気象学会

雑誌

気象集誌. 第2輯 (ISSN:00261165)

巻号頁・発行日

vol.14, no.8, pp.381-404, 1936

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This paper is composed of two parts. The first part deals with the general theory of long-period seismographs having a device of the mechanical registration and the properties of horizontal pendulum of Z&ouml;llner's befilar type. As to be convenient for designing these instruments we investigated about the style of the suspended bodies as well as the tension of the fibre in the equilibruim state. The results thus obtained are graphically represented in Fig. 3, 4 and 5.<br>In the second part is described an electrical methol which makes to record mechanically the motion of long-period pendulum with a sufficient magnification and without any frictional resistance. For this purpose we adopted a system of series, i.e. horizontal pendulum (seismograph)&rarr;coil (generator)&rarr;amplifier&rarr;recording galvanometer. The seismograph is similarly constructed in size and figure as Galitzin's one. The horizontal pendulum, having a mass of 10kg hanged with piano wires of 0.7mm in diameter, bears a coil (20, 000&Omega;) and alminium plate. Both lie in the magnetic field and serve as the generator and damper respectively. In this seismograph it is not so difficult to get a period more than 40 sec. the pendulum continues to freely oscillate for a long while without any considerable decrease in amplitude if the effect of the damper be properly taken away.<br>The recording galvanometer was specially designed for this purpose. It is of a moving coil type and bears a recording pen with a straw (strengthened by bakelite suffusion) style in order to get registration on a smoked paper (See photopraphs of Fig. 16). The resistance of this galvanometer is 5, 600&Omega;, the proper period of it 0.4 sec., the damping ratio <i>v</i>=4 in the case of open circuit. It causes a deflection of about 1cm. on the paper for a current of 0.1mA when the arm length is 16cm.<br>The current generated in the coil by earthquakes is in Galitzin's method lead to a long-period sensitive galvanometer and observed photographically, but here we magnified it by a voltage and current amplifier to get a current large enough to act the mechanically recording galvanometer of short-period mentioned above. The wiring of the amplifier is shown in Fig. 6. This amplifier consists of three stages of push-pull type directly coupled. Vacuum tubes B 228 and A 409 are used. The formers of earlier two stages are operated by 2 and 200 Volt storage battery and the latters of the last stage by rectified current obtained from 100 Volt A. C. line. We can obtain a sufficient stableness of this amplifier for the continuous routine observation and its adjustment and treatment are not so difficult. If the condensers used in this amplifier be omitted or changed properly for others of different capacity, we can get to some extent a desirable condition of amplification for the current generated by earthquakes according as its period varies. In a word, the magnification curve for stationary oscillations obtained by the present arrangement is very alike to that of Galitzin's instruments. But there are some inevitable defects because the recorded seismogram is magnified in very complex manner except when the earthquake motion takes place in regular oscillations, and even in this case a remarkable phase lag is observed for rapid oscillations.<br>In brief, our intension is to get the mechanically registered seismogram applied to the Galitzin's seismograph, because the photographic recording has various inconveniences for a routine work. Some examples of seismograms obtained by the present method are shown in Fig. 16. Of course there may be many things to be improved in our apparatus, it seems, however, to suggest that the registcring method of this kind may be useful for the routine observation of distant earthquakes by long-period seismographs, and also applicable to observations of other geophysical phenomena, such as terrestrial magnetism, earth current, wind, temperature and pressure of the air etc.

著者

和達 清夫

出版者

公益社団法人 日本気象学会

雑誌

気象集誌. 第2輯 (ISSN:00261165)

巻号頁・発行日

vol.12, no.9, pp.496-497, 1934

著者

和達 清夫

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.100, no.1, pp.1-2, 1991-02-25

著者

和達 清夫

出版者

公益社団法人 日本気象学会

雑誌

気象集誌. 第2輯 (ISSN:00261165)

巻号頁・発行日

vol.11, no.11, pp.505-512, 1933

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This earthquake was precisely investigated by Mr. Isikawa in the last year. (this journal Vol. 10, No.4.) This report is a supplementary one to it, especially on the point of the focal depth and reflected waves, taking advantage of the travel time table calculated by the author and others.

著者

和達 清夫

出版者

公益社団法人 応用物理学会

雑誌

応用物理 (ISSN:03698009)

巻号頁・発行日

vol.3, no.9, pp.323-331, 1934

著者

和達 清夫

出版者

公益社団法人 日本気象学会

雑誌

気象集誌. 第2輯 (ISSN:00261165)

巻号頁・発行日

vol.10, no.9, pp.540-551, 1932

被引用文献数

1

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The velocity ratio of P and S waves is obtained by many authors to be nearly constant everywhere in the earth's crust. In the present investigatio_??_, is treated this problem by a method of <i>t_p-T_p-s</i> diagram which gives the relation between the arrival time of P and duration of (P-S). Examining in many cases of large earthquakes of both shallow and deep origins occurred in our country, the relation is obtained to be approximately linear as is expected, especially in the cases of deep-seated earthquakes. From these investigations, the velocity ratio of P and S waves is obtained as about 1.73 in the upper part, it may be probably the so-called Mohorovicic layer, but its value seems to differ in different localities; while, in the deeper part nearly a constant value of 1.79 is obtained. Thus, using the result we are able to obtain the depth of seismic focus by a simple method, especially in case of deep-seated earthquakes.

著者

和達 清夫 益田 クニモ

出版者

公益社団法人 日本気象学会

雑誌

気象集誌. 第2輯 (ISSN:00261165)

巻号頁・発行日

vol.11, no.9, pp.389-394, 1933

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This report is presented for the purpose of showing the general activity of recent large earthquakes (1919-1928, Sep.) in the world. The materials were all taken from I. S. S. issued from the University Observatory, Oxford.

著者

和達 清夫

出版者

公益社団法人 日本気象学会

雑誌

気象集誌. 第2輯 (ISSN:00261165)

巻号頁・発行日

vol.5, no.6, pp.119-145, 1927-06-20 (Released:2009-02-05)

参考文献数

13

被引用文献数

6 10

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地震の震源の深さに就いては從來種々の結果が得られて居るが、近來近地地震觀測の精密さに依り震源の深さは殆んど總ての地震に就き四十粁内外が最も普通となされて居る。我が國に起る多くの地震に就きても、多くの研究は悉くこの程度の淺き震源の深さを與へて居る。而るに著者は或種の地震を研究したる結果、其れ等が三百粁以上の深き震源を有すべき結論に達し、假りに之を深層地震と呼ぶ事にした。此の結論が正しければ、從來の地震源捜索法に改良を要し、又過去の地震表の訂正を要することゝなる。依うて本論文に於て其の決論の達したる研究を述べて學會の批判を仰がんと欲す。多くの集蒐されたる深層地震中特に大正十五年七月廿七日の地震は、本州中央部の地下約三百五十粁の深さに發現したる代表的の深層地震なりと考へらるゝを以て、其の記象型及び震波の走時に關し詳細の調査がなされて居る。本論文に於ては右研究の結果として、地震源の深さ及び地殼上層に於ける震波の傳播速度が求められた。かゝる深層地震の存在は近地地震の觀測に依り地殼上層の物理的状況の研究をなすのに極めて好都合の材料を與ふるものである。近年の觀測に於て確に深層地震であると決定されるものを求め其等の分布から深層地震帶なるものが求められた。この深層地震帶は從來の地震帶と略直角に交叉し從來のものと別にある新しい意味を持つ地震帯であり、其の地震帶附近に於て近來の大地震が發現して居るのも興昧ある事である。此の地震帶に就いても大體の調査がなされて居るが、淺き大地震と深層地震との間に何等かの關係が認められさうである。此の問題は大地震の警戒に關し實際的に興味ある問題を與へるものと思はれる。

著者

和達 清夫

出版者

東京帝国大学地震研究所

雑誌

東京帝國大學地震研究所彙報 = Bulletin of the Earthquake Research Institute, Tokyo Imperial University (ISSN:00408972)

巻号頁・発行日

vol.1, pp.55-58, 1926-10-15

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The pulsatory oscillations were observed at the seismologica observatory at Hommaru, Tokyo from Dec. 1st. 1925 to Jan. 21st. 1926. The Galitzin seismograph with photographic registration was used for the purpose. The pulsations observed at Tokyo may be classified into three sorts according to their periods: (A) those with a period shorter than 3 sec. (B) regular type with a period of 4-8 sec. and (C) irregular type with a period of more than 30 sec.

著者

和達 清夫 中曽根 康弘

出版者

一般社団法人情報処理学会

雑誌

情報処理 (ISSN:04478053)

巻号頁・発行日

vol.1, no.1, 1960-07-30

著者

和達 清夫

出版者

水利科学研究所

雑誌

水利科学 (ISSN:00394858)

巻号頁・発行日

vol.7, no.4, 1963-10

著者

和達 清夫

出版者

水利科学研究所

巻号頁・発行日

no.33, pp.1-6, 1963 (Released:2016-05-23)

著者

和達清夫監修

出版者

東京堂出版

巻号頁・発行日

1960