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Volume 23 (1977)
- Issue 4 Pages 213-
- Issue 3 Pages 135-
- Issue 2 Pages 57-
- Issue 1 Pages 1-
Volume 23, Issue 1
Displaying 1-8 of 8 articles from this issue
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Minoru TAZIMA, Akira YAGUCHI1977 Volume 23 Issue 1 Pages 1-8
Published: June 25, 1977
Released on J-STAGE: September 07, 2010
JOURNAL FREE ACCESSThe direct and inverse geodetic problems based on the M0L0DENSKII's closed for mulas were solved by the iteration computation method for non-linear function equation system. The results of numerical examples are as follows.(1) In medium and large distance problems having 40 km-120 km, the final converged values were obtained after two or three iterations with the accuracy of 1"×10-12 in angle and 1×10-8 cm in distance as shown in Table I.(2) In the case of short distance problem having the latitude and longitude differences of both 1" and elevation difference of 400 m between two geodetic points, however, an error of 5"×10-11 or so still remained after 8 iteration computations. Furthermore, in a very short distance problem (the latitude and longitude differences of both 0.1" and elevation difference of 400 m), about 10 iterations were required for obtaining the accuracy of 1"×10-10. The reason of such slow convergent speed in the iteration for solving short distance problems seems to originate from the socalled cancelling error, which appears in the computation of formulas containing the form of the subtraction of nearly equal two terms such as MOLODENSKII's formulas.View full abstractDownload PDF (744K) -
Katsumi NAKANE1977 Volume 23 Issue 1 Pages 9-16
Published: June 25, 1977
Released on J-STAGE: September 07, 2010
JOURNAL FREE ACCESSFor calculating displacement vectors of crustal movements from repeated triangulation surveys, it is convenient to put the old survey coordinate X as the approximate coordinate for every unknown station in new survey adjustment because of the simplicity that displacement vectors are equal to the unknown x in the new survey adjustment. The adjustment of free network is the most usefull in the customary methods because it does not need any fixed stations in the network. However, there is a problem that some large displacement vectors are distributed to all the triangulation stations in the network in this method. To avoid such a problem we have an idea of regulating the movement of a geodetic triangle consisting of three stations. The chosen three stations are controlled by the following conditionsROTATION =0, and TRANSLATION =0, and if the network has no measurement of distance, in addition to them the other conditionDILATATION =0is added. In choosing the control stations they should be located in a stable area in the network.View full abstractDownload PDF (581K) -
Naosuke SEKIGUCHI1977 Volume 23 Issue 1 Pages 17-24
Published: June 25, 1977
Released on J-STAGE: September 07, 2010
JOURNAL FREE ACCESSAssuming that the Chandlerian wobble is excited by a function which consists of random excitations of short durations, some relations between polar motion and the excitation function are deduced. It is shown that the square of the dispersion of the excitation function multiplied by the time interval is a convenient parameter to designate the character of the excitation, and its value is obtatined by two methods based on different principles, namely from the square mean of the polar radius and from the third differences of the polar path, respectively as 80±54 and 40±17 (s.e.), (0."001)2yr. The present model of the excitation does not conflict with the results of the investi gation of WILSON and HAUBRICH (1976).View full abstractDownload PDF (690K) -
Sadakatu IZUTUYA1977 Volume 23 Issue 1 Pages 25-35
Published: June 25, 1977
Released on J-STAGE: March 01, 2011
JOURNAL FREE ACCESSThe Mogi model is an important approach to the crustal uplift associated with volcanic activities on the basis of elastic deformation of a semi-infinite solid with a spherical cavity. The multiple Mogi model newly proposed in this paper is an approach to a dilatant expansion of the crust, in which many spherical microcracks lie scattered under the Gaussian distribution law of statistics. Theoretical considerations of the shape of the Matsushiro uplift suggest that a multiple Mogi process has most probably taken place in the swarm epicentral region. roundwater flow into microcracks has made pore pressure increasing during th period of uplift. After spring water flowing along the fissure zone, the mean depth of micro crack istribution has become shallower due to the upward expansion of the dilatant zone and then the horizontal length scale of the dilatant zone has become greater than the vertical scale.View full abstractDownload PDF (993K) -
Sadakatu IZUTUYA1977 Volume 23 Issue 1 Pages 36-41
Published: June 25, 1977
Released on J-STAGE: March 01, 2011
JOURNAL FREE ACCESSGravimetric comparisons have repeatedly made between the Tokyo and the Kakioka Fundamental Gravity Stations since 1963 by using LaCoste & Romberg gravimeters. The Gravity difference between them amounts to about 177 mgal. The gravity value at the Tokyo Fundamental Gravity Station relative to the Kakioka Station decreased at a rate of 11μgal/year till 1969, but afterwards it has turned increasing at a rate of 18, i gal/year during these three years. The gravity decrease is well coincident with the groundwater leveldown whichwas accompanied with the ground subsidence. On the other hand, the gravity in crease can be explained as the ground water level recovery. We estimate effective porosity of soil as about 20% in the gravity-decreasingperiod and 18% in the increasing one. Judging from these results, we conclude that the soil consolidation due to the ground subsidence has scarecely occurred throughout.View full abstractDownload PDF (2084K) -
Yukio HAGIWARA1977 Volume 23 Issue 1 Pages 42-43
Published: June 25, 1977
Released on J-STAGE: September 07, 2010
JOURNAL FREE ACCESSAn effect of tidal change in groundwater level on the gravity field is not small in seaside areas. It is concluded that gravity stations should be located beyond at least 50 m apart from the coastline, so that semidiurnal groundwater level change may scarcely act on the gravity field.View full abstractDownload PDF (180K) -
Naomi FUJITA1977 Volume 23 Issue 1 Pages 44-45
Published: June 25, 1977
Released on J-STAGE: September 07, 2010
JOURNAL FREE ACCESSDownload PDF (217K) -
Yasuhiro GANEKO1977 Volume 23 Issue 1 Pages 46-47
Published: June 25, 1977
Released on J-STAGE: September 07, 2010
JOURNAL FREE ACCESSThe evaluation of the truncation error coefficient Qn introduced by MOLODENSKII et al. requires generally a complicated mathematicalprocess especially at high degrees, if we want to obtain accurate values of Qn The author presents a practical approximation formula which can be used of evaluate Qn at high degrees with a sufficient accuracy for the practical\purpose and to decrease computer time drasti cally.View full abstractDownload PDF (225K)
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