TERRAPUB Earth, Planets and Space

Earth Planets Space, Vol. 52 (No. 11), pp. 979-984, 2000

LETTER

Crustal movements around the Beppu Bay area, East-Central Kyushu, Japan, observed by GPS 1996-1998

Y. Fukuda1, M. Itahara1, S. Kusumoto2, T. Higashi1, K. Takemura1, H. Mawatari3, Y. Yusa3, T. Yamamoto4, and T. Kato5

1Department of Geophysics, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
2School of Marine Science and Technology, Tokai University, Shimizu 424-8610, Japan
3Beppu Geothermal Research Laboratory, Kyoto University, Beppu 874-0903, Japan
4Meteorological Research Institute, 1-1 Nagamine, Tsukuba 305-0052, Japan
5Earthquake Research Institute, University of Tokyo, Tokyo 113-0032, Japan

(Received December 31, 1999; Revised August 2, 2000; Accepted August 15, 2000)

Abstract: In order to detect the crustal movement in the Beppu Bay area, where the highest intra-plate strain rates in Japan is expected, precise GPS measurements have been repeatedly conducted since 1994 at one-year intervals. The result shows N-S or NNE-SSE extension taking place at a rate of more than 10 mm/yr around Beppu Bay. This is essentially consistent with the result obtained by the geodetic survey conducted over the last 100 years, and it suggests a constant rate of crustal motion over the period. The result gives a strong constraint for future modeling of the stress field recovery in the area. However, we failed to identify whether the movement occurred at any specific fault. A denser array of GPS points is needed in the area, and especially near the major faults, in order to investigate possible fault-related motion.


Corresponding author E-mail: fukuda@kugi.kyoto-u.ac.jp


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