Special Issue: Application of GPS and other space geodetic techniques to Earth Sciences (2)
GPS and EDM monitoring of Unzen volcano ground deformation
Earth, Planets and Space volume 52, pages 1015–1018 (2000)
Following 198 years of dormancy, an eruption started at Mt. Fugen, the main peak of Unzen volcano, in Kyushu, Japan, in November 1990. A dacite lava dome began to grow in May 1991. We installed the surveying points of GPS in 1992 around the lava dome in order to observe the ground deformation that accompanied the growth of the lava dome. In the winters of 1993 and 1994, we observed swift ground deformations that radiated from the vent of the volcano. It was presumed that rising magma accumulated and expanded the volcano body. After the lava effusion stopped in 1995, we also installed surveying points on the lava dome. EDM mirrors were permanently fixed to the large rocks with bolts. A GPS survey was carried out 2 or 3 times each year to estimate the 3-dimensional displacement. The result of the EDM survey showed that the baselines from the flank of the volcano were shortening 5 mm per day, and the result of the GPS survey showed that the displacement vector of the dome was parallel to the direction of the steepest slope of the old volcano body. This indicates that the inside of the lava dome is still very hot, and that deformation of the dome is viscous.
Nakada, S., H. Shimizu, and K. Ohta, Overview of the 1990–1995 eruption at Unzen volcano, J. Volcanol. Geotherm. Res., 89, 1–22, 1999.
Ohmi, S. and T. Matsushima, Ground deformation around the lava dome of Unzen Volcano Monitored with GPS, Bull. Volcanol. Soc. Japan, 38, 129–133, 1993 (in Japanese).
Saito, E., S. Suto, T. Soya, K. Kazahaya, Y. Kawanabe, H. Hoshizumi, K. Watanabe, and H. Endo, Geodetic monitoring using EDM before and during the 1991–1992 lava extrusion of Fugen-dake, Unzen Volcano, Kyushu, Japan, Bull. Geol. Surv. Japan, 44, 639–647, 1993 (in Japanese with English abstract).
Shimabara Earthquake and Volcano Observatory (SEVO), Volcanic Activity of Unzen Volcano (February 1999–May 1999), Report of Coordinating Committee for Prediction of Volcanic Eruption, 74, 103–108, 1999 (in Japanese).
Yamashina, K. and H. Shimizu, Crustal deformation in the mid-May 1991 crisis preceding the extrusion of a dacite lava dome at Unzen volcano, Japan, J. Volcano. Geotherm. Res., 89, 43–55, 1999.
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Matsushima, T., Takagi, A. GPS and EDM monitoring of Unzen volcano ground deformation. Earth Planet Sp 52, 1015–1018 (2000). https://doi.org/10.1186/BF03352323
- Global Position System
- Ground Deformation
- Lava Dome
- Global Position System Station
- Global Position System Observation