測地学会誌
Online ISSN : 2185-517X
Print ISSN : 0038-0830
ISSN-L : 0038-0830
33 巻, 3 号
選択された号の論文の9件中1~9を表示しています
  • 田中 穣, 中野 博美
    1987 年 33 巻 3 号 p. 171-180
    発行日: 1987/11/25
    公開日: 2011/07/05
    ジャーナル フリー
    The 1891 great Nobi earthquake is considered to have been the greatest (M-8) intraplate earthquake in Japan in the past 100 years. It provides much information on the long-term prognosis of earthquakes in this district which is affected by postseismic movements. The postseismic movements on and near the ruptured fault zone (the Neodani-Umehara fault) in the period of almost 100 years since the 1891 quake have been inves-tigated by analyzing the data from repetitive leveling and triangulation surveys ever since 1889 in the south Chubu district of central Japan. The postseismic vertical movement due to aseismic slip on and near the edge of the south-eastern section of the ruptured fault zone continued to subside for about 80 years since the occurrence of the quake, but in this last 20 years, the movement has changed to an uplifting movement. That is, following the final stage of o-phase due to aseismic slip in the phase cycle of seismic crustal movement in this district, the first stage of a-phase started around 1970. Two zones showing relatively large maximum shear strains, were detected along the main fault and along the direction of a curved line from WSW to E nearly perpen-dicular to the main fault. The latter zone seems to agree with the leading edge of the Philippine sea plate. These facts show that the strain energies were accumulated elastically by postseismic slow deformation in the period of about 80 years after the 1891 quake and mostly released by generating earthquakes in the periphery of the fault. A non-local anomalous upheaval around Ookuwa-mura near the Atera fault was detected from the leveling data during the period from 1966-7 to 1984 just before the Western Nagano prefecture earthquake (1984 M 6.8). It is necessary to conduct further investigation especially around the Atera fault or Mt. Ontake to comfirm whether the upheaval was released by the earthquake or not.
  • 中根 勝見
    1987 年 33 巻 3 号 p. 181-183
    発行日: 1987/11/25
    公開日: 2010/09/07
    ジャーナル フリー
     ケニア測量局において筆者は,ケニアにおけるリフトバレーを横切る1等水準測量(約60km)を25年ぷりに実施した.その結果,リフトパレーの底は,年間1~2mm沈下していると推定できる.
  • ―ラコスト重力計(G型)による重力値の精密決定―
    中川 一郎, 志知 龍一, 中井 新二, 中村 佳重郎, 東 敏博, 李 瑞浩, 陳 益恵, 王 東初
    1987 年 33 巻 3 号 p. 185-204
    発行日: 1987/11/25
    公開日: 2010/09/07
    ジャーナル フリー
    An international gravimetric connection between Japan and China as well as domestic ones in both countries were carried out during the period from October 1985 to February 1986 by means of four LaCoste & Romberg gravimeters (G-196, G-305, G-484 and G-605) for the purposes of (1) calibrating scale values of each gravimeter employed, (2) precisely determining a gravity value at each measured station occupied, (3) establishing a precise gravity net composed of 24 gravity stations in the standard baseline field of gravity surveys in Lushan Mountains recently arranged by the Chinese authority, (4) experimentally reconfirming specific characteristics of mechanical sensitivity of LaCoste & Romberg gravimeters revealed on some gravimeters through the international gravimetric connections along the Circum-Pacific zone performed in 19791982, and (5) clarifying dependencies of gravimeters, from data obtained under various measurement conditions, on disturbing environmental effects. For the domestic gravimetric connections in China, three other LaCoste & Romberg gravimeters (G-793, G-808 and G-818) belonging to the Seismic Observation Brigade, State Seismological Bureau, took part in the present investigations. These purposes have successfully been attained, although the present article only deals with the purposes (1), (2) and (3) among them. The methods of data analyses followed to those developed through the data analyses for the international gravimetric connections along the Circum-Pacific zone, except for newly taking periodic errors (inequality of a gear system) into account. The scale values of three gravimeters (G-196, G-305 and G-484) participated in the Circum-Pacific gravimetric connections have been rerevised by the present inves-tigations, although the amounts of rerevision were very small. For the others, their scale values were revised by the present investigations for the first time. Taking advantage of these revised scale values and also taking the periodic errors into consideration, gravity values at all the measured stations, including those in the standard baseline field of gravity surveys in Lushan Mountains, have precisely been determined so that these stations will contribute to calibrate scale values of the other gravimeters and/or to examine a possible gravity change in the future. It is emphasized that the information on both the scale values and the periodic errors for each gravimeter is essentially important to a high precision gravimetry, because errors arisen from these sources are neither negligibly small nor random.
  • 藤井 陽一郎, 宮本 秀晴
    1987 年 33 巻 3 号 p. 205-214
    発行日: 1987/11/25
    公開日: 2011/03/01
    ジャーナル フリー
     光波測距において測距儀の表示する測定値をDr,標準大気補正をd.Snとすれば,任意条件下では追加補正dCが加えられることによって正しい測定値SがS=Dr+ΔSn+ΔCのごとく求まる.dSnは,大気中の平均屈折Nmを両観測点での気温・気圧の測定値の平均値Tm,P伽を使って推定して容易に計算できる.またΔCは地表と光路の間の温位の差ae,Cを光路Xに沿って積分して求められる.
    ΔC=10-6・∫S 0 Δθxdx
    ここにNmはTm,pmから求めた平均屈折率で,sは全光路の長さである[ANGUS・LEPPAN and BRUNNER].補正dCの計算には地形に関する数値積分のほかヒートフラックスHや摩擦風速U*などの項が含まれる. ところで,測定路線に沿う平均的な光路の高さhとオブコフの長さLとから接地層の大気の安定度は3つに分けられ,それぞれについてde,cの推定に必要な経験式が提案されている[ANGUS・LEPPAN].この提案を採用して大気安定度の3つの領域に対応した不安定(主として昼間)と安定(真夜中)の場合の計算を遂行し,新たにacを求める式をつくった. 新たな大気補正の一般式の有効性を確かめるために1985年7月から8月にかけて地表状態の異る2ヶ所において試験観測を実施した.いまある辺長について任意時刻での観測に標準大気補正のみを適用したときのS.D.をA,一般化大気補正を試みたときのS.D.をBとして一般化大気補正適用の有効率をη={A-B)/A}×100で定義すると,全体として数%程度の精度の向上が認められ,昼間の観測も少しはよくなることが分った.しかしながら辺長が10km以上の場合には逆に悪くなった場合もあり,予想されたごとくこの方式は数km程度以下の辺長測定にしか適用できない. 計算の過程に現われる最大の粗い近似はヒートフラックスの推定であり,この点になお改良の余地がある.ヒートフラックスを実測することもできるが,今のところ手間がかかりすぎるので,もっと効率的な推定式を考案する必要がある.
  • ―第1部浅い大規模地震(M>7.45)のモルフォロジー―
    坪川 家恒
    1987 年 33 巻 3 号 p. 215-243
    発行日: 1987/11/25
    公開日: 2011/07/05
    ジャーナル フリー
    If the earthquake phenomena are caused by the external force as the result of the large scale internal activities of the Earth which are steady and continuous in the geophysical time scale, such phenomena should indicate the progress of time in considerably certain accuracy in the crust and the uppermost mantle of similar physical properties. In this point of view, the writer reported several papers. In the present paper, the writer arranged the points of arguments of the former reports and established the following five a priori hypotheses: 1) Gutenberg-Richter's formula of N. 2) The precursor duration time T is inversely proportional to N. 3) The general idea of the earthquake province-domain is proposed, and in one province NT=1. 4) Giant earthquakes (>8.05) occurr sequentially. 5) The maximum scale of giant earthquakes Mmax=8.40.4) and 5) are partly established by evidencies.These hypotheses must be a posteriori verified. In the Part 1 of this report, the writer examined the erathquakes occurred from 1600 A. D. to the recent times near the main land of Japan, and the earthquakes along the Circum-Pacific zone from Kamchatka to Taiwan in the recent period. In the results, he attained the following conclusions: a) The activity of large earthquakes seems to begin after a quiet period of 30 or more years and ends in an average cycle of about 117 years±several years. b) At the end of the cycle, the relation NT =1 is concluded quite accurately. c) Giant earthquakes larger than 8.05 play the lead in large earthquakes, and the earthquakes of M8.05-7.45 display the supplementary activity. The total energy of giant earthquakes seems to be more than 60% of the total energy of earthquakes in the active seismic zone.
  • ―観測結果と伸縮計との比較―
    柳沢 道夫
    1987 年 33 巻 3 号 p. 245-257
    発行日: 1987/11/25
    公開日: 2010/09/07
    ジャーナル フリー
    The earth strain has been observed simultaneously by strain gages and extenso meters in the tunnel of the Nokogiriyama Crustal Movement Observatory during the period from January 1986 to March 1987. The data processing is made by the least square method and the BAYTAP-G program. The strain response to atmospheric pressure changes are much affected by the topography over the observational tunnel. Tidal factors obtained by extensometers are 210 times greater than those obtained by strain gages.
  • 村上 亮, 板橋 昭房
    1987 年 33 巻 3 号 p. 258-271
    発行日: 1987/11/25
    公開日: 2010/09/07
    ジャーナル フリー
     本稿では,投影計算においてジオイド高を無視した辺長データをもとにして行う三辺測量網平均計算の持ち得る系統誤差について報告する.測距データの楕円休上への投影をを行う際にジオイド高を考慮したものと,考慮しないものとの二種類の網平均計算を,国土地理院が行った精密測地網一次基準点測量の東北日本部を対象にして実施した.ジオイドにはRAPPによるものを使用した.これらの結果とNNSS測位成果及び従来成果とあ比較について述べる.この比較によって,三辺測地網平均計算に於いては,ジオイド高が無視されるべきでないことが示される.また,従来測地網に於ける北海道の大きな回転が見出された.
  • 中川 一郎
    1987 年 33 巻 3 号 p. 273-275
    発行日: 1987/11/25
    公開日: 2010/09/07
    ジャーナル フリー
  • 中川 一郎
    1987 年 33 巻 3 号 p. 277-288
    発行日: 1987/11/25
    公開日: 2010/09/07
    ジャーナル フリー
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