大津の坑内における地殻の経年変動の観測(<小特集>岩石力学小特集)
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概要
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The observations on secular changes of the crustal movements by means of extensometers and water-tube tiltmeters have been carried out in a tunnel of the former Tokaido railway at Otsu. The strain elements (main strains and areal strains) have been obtained from these observations of the extensions in the three azimuths and the vertical directions. And the recent changes of these elements for the period 1970 to 1973 have been compared with the mean variation in the whole period from 1961 to 1973. The azimuths of the main strains in the recent period are equal to those of the mean values, but the magnitudes in absolute value of these strains are different from those of the mean values. The constancy in the azimuths of the main strains corresponds well with those of the main stresses of the earthquakes and the crustal movements in this district obtained by the triangulations. The observations of the same components at the departed points on a same azimuth have been carried out simultaneously, and the development of the crustal movement has been detected. The ground tilting has been determined by means of the water tube tiltmeters at 2 points in the tunnel. It seems that the directions of these tiltings have close correlation with the topography around the observatory. The inclination around the observatory has amounted to 0.5 second for about twenty years. According to the observation by means of the recording type tiltmeter, it seems that the magnitudes and phases of the annual tiltings depend very much on the level down of the ground water in the tunnel. It seems also that the timing of anomalous changes of the tiltings correspond to that of the frequency of the felt earthquake. It was also found that many earthquakes have occured during the wet seasons in this district.
- 社団法人日本材料学会の論文
- 1974-05-15