九州東南部における光波測量 (序報)

Abstract

Two base-line networks for distance measurement with Geodimeter are constructed at the coastalregion of Miyazaki prefecture in Kyushu district. The Miyazaki network consists of 8 base-linesand the Nobeoka network consists of 4 base-lines. Results of repeated surveys of these networkswill reveal the horizontal strain changes in this region which neighbors on the source region of histo-rical major earthquakes in the Hyuganada sea.At the Miyazaki network, the first survey was carried out at March and the second at Decemberin 1981. Observed strains for these 9 monthes contain quantitative uncertainty but qualitativelyagree with the results of continuous observations by extensometers at the Miyazaki Crustal Move-ment Observatory and those of repeated surveys at rhombus base-lines and first triangulation net byG.S.I.. The Nobeoka network was surveyed only once at December in 1981.An effective distribution of base-line azimuthes is also discussed to estimate a homogeneousstrain field.