OBSERVATIONS OF CRUSTAL STRAINS BY ELECTRO-OPTICAL MEASUREMENT (PART 1)

Abstract

Results from repetitional measurements of six base-line networks founded in the western Japanby a geodimeter are presented. Base-lines in the Tottori district intersect two seismic faults, theYoshioka and Shikano faults. As to the base-lines at Shimoda and in a tunnel at Amagase CrustalDeformation Observatory, comparison of the results from the electro-optical measurements withthose from continuous observations by extensometers is possible. At the network in Wakayama weaim to observe the strain accumulation relating to local earthquake occurrences in this district. Forthe purpose of detection of the crustal strain accompanied by the characteristic movement of thesouthern coast in Shikoku, a network has been established in Kochi City. Significant changes ofmeasured lengths of these base-lines are hardly observable in the results from three observationsfrom 1968 to 1971.Results from repetitional measurements of six base-line networks founded in the western Japanby a geodimeter are presented. Base-lines in the Tottori district intersect two seismic faults, theYoshioka and Shikano faults. As to the base-lines at Shimoda and in a tunnel at Amagase CrustalDeformation Observatory, comparison of the results from the electro-optical measurements withthose from continuous observations by extensometers is possible. At the network in Wakayama weaim to observe the strain accumulation relating to local earthquake occurrences in this district. Forthe purpose of detection of the crustal strain accompanied by the characteristic movement of thesouthern coast in Shikoku, a network has been established in Kochi City. Significant changes ofmeasured lengths of these base-lines are hardly observable in the results from three observationsfrom 1968 to 1971