Abstract
Microgravity measurements and levelling surveys on volcanoes are not always easy to make, but are useful for studying volcanic processes quantitatively. Gravity changes associated with volcanic activity are not always significant. Precision of microgravity measurements depend critically on the procedures adopted, and those applied in the present paper are described. Levelling technique is now orthodox, and some empirical laws relating ground deformation to volcanic activity are deduced from the accumulated data. Gravity changes occur at the same time and places as ground deformations. The relationship between microgravity and height changes are discussed from the standpoint of analyzing the data obtained on volcanoes. The observational results obtained on four volcanoes in Japan are separately analyzed because each volcano exhibits different patterns of gravity changes and deformations. During the 1977–1982 activity of Usu volcano, deformation was accompanied by microgravity changes frequently observed at a particular benchmark at the base of the volcano for about five years. The gravity changes prove to be not a direct effect of magma movements but to be caused by the deformations of ground strata and aquifers around the benchmark. The 1983 eruption of Miyakejima volcano was associated with local gravity changes around the eruptive fissures due to magma intrusion which was approximately modelled. Similarly the 1986 eruption of Ooshima volcano caused gravity changes on the volcano, but these were poorly correlated with elevation changes and their origins were not uniquely interpreted. To detect gravity changes associated with the activity of Sakurajima volcano, an equigravity point was selected at the north of the volcano besides the gravity points on and around the volcano itself. The probable gradual accumulation of magmas beneath the volcano for eight years is substantiated by observed microgravity and elevation changes.
Similar content being viewed by others
References
Dzurisin D, Anderson LA, Eaton GP, Koyanagi RY, Lipman PW, Lockwood JP, Okamura RT, Puniwai GS, Sako MK, Yamashita KM (1980) Geophysical observations of Kilauea volcano, Hawaii, 2. Constraints on the magma supply during November 1975–September 1977. J Volcanol Geotherm Res 7:241–269
Filson J, Simkin T, Leu L-K (1977) Seismicity of a caldera collapse: Galapagos Islands 1968. J Geophys Res 78:8591–8622
Hagiwara Y (1977) The Mogi model as a possible cause of the crustal uplift in the eastern part of Izu Peninsula and the related gravity change. Bull Earthq Res Inst 52:301–309 (in Japanese)
Iida K, Hayakawa M, Katayose K (1952) Gravity survey of Mihara Volcano, Ooshima Island, and changes in gravity caused by eruption. Geol Surv Jpn Rep 152:28 pp (in Japanese with English summary)
Ishihara K, Yokoyama I, Maekawa T, Tajima H (1986) Precise gravity measurements on Sakurajima volcano and around Kagoshima Bay. Rep 5th Joint Obs Sakurajima Volcano: 33–40 (in Japanese)
Ishihara K, Miyamachi H, Yokoyama I, Tajima H, Sawada M (1988) Precise gravity measurements on Sakurajima volcano and around Kagoshima Bay. Rep. 6th Joint Obs Sakurajima Volcano:47–53 (in Japanese)
Jachens RC, Eaton GP (1980) Geophysical observations of Kilauea volcano, Hawaii, 1. Temporal gravity variations related to the 29 November, 1975, M=7.2 earthquake and associated summit collapse. J Volcanol Geotherm Res 7:225–240
Johnsen GV, Bjornsson A, Sigurdsson S (1980) Gravity and elevation changes caused by magma movement beneath the Krafla Caldera, Northeast Iceland, J Geophys 47:132–140
Johnson DJ (1987) Elastic and inelastic magma storage at Kilauea Volcano. US Geol Surv Prof Pap 1350:1297–1306
Miyazaki T (1988) Ground deformations of Ooshima caldera associated with the 1986 eruption of Izu-Ooshima volcano. Bull Volcanol Soc Jpn Spec Issue 32 (in Japanese, in press)
Mogi K (1958) Relations of eruptions of various volcanoes and the deformation of the ground surfaces around them. Bull Earthq Res Inst Univ Tokyo 39:99–134
Nettleton LL (1976) Gravity and magnetics in oil prospecting. McGraw-Hill, New York, pp 464
Nishimura S, Abe E, Katsura K (1988) Secular changes in vertical gravity gradients on and around Sakurajima volcano. Rep 6th Joint Obs Sakurajima Volcano:55–62 (in Japanese)
Ohshima H (1979) Gravity changes associated with volcanic activities. Master Thesis, Fac Sci Hokkaido Univ pp 66 (in Japanese)
Okubo S, Watanabe H, Tajima H, Sawada M, Sakashita S, Yokoyama I, Maekawa T (1988) Gravity changes caused by the 1986 eruption of Izu-Oshima Volcano. Bull Earthq Res Inst (in press) (in Japanese)
Rundle JB (1978) Gravity changes and the Palmdale uplift. Geophys Res Lett 5:41–44
Rymer H, Brown GC (1987) Causes of microgravity change at Poas volcano, Costa Rica: an active but non-erupting system. Bull Volcanol 49:389–398
Savage JC (1984) Local gravity anomalies produced by dislocation sources. J Geophys Res 89:1945–1952
Tajima H, Hagiwara Y, Ohkawa S, Yokoyama I (1975) Precise gravity measurements on Sakurajima volcano and around Kagoshima Bay. Rep 1st Joint Obs Sakurajima Volcano: 50–57 (in Japanese)
Tajima H, Izutsuya S, Ooshima H, Ohkawa S, Yokoyama I, Ishihara K (1977) Precise gravity measurements on Sakurajima volcano and around Kagoshima Bay. Rep 2nd Joint Obs Sakurajima Volcano:45–54 (in Japanese)
Tajima H, Sawada M, Yokoyama I, Maekawa T, Watanabe H (1985) Precise gravity measurements on Ooshima volcano-May 1983. Rep 1st Joint Obs Ooshima Volcano:53–62 (in Japanese)
Tsuboi C (1983) Gravity. Allen & Unwin, London, pp 254
Walsh JB (1975) An analysis of local changes in gravity due to deformation. Pageoph 113:97–106
Walsh JB, Rice JR (1979) Local changes in gravity resulting from deformation. J Geophys Res 84:165–170
Watanabe J (1983) Changes in water level and their implications to the 1977–1978 activity of Usu volcano. In: D Shimozuru, I Yokoyama (eds) Arc volcanism: physics and tectonics. Terra Scientific Publishing Company, Tokyo, pp 81–93
Yokoyama I, Tajima H (1957) A gravity survey on Volcano Mihara, Ooshima Island by means of a Worden gravimeter. Bull Earthq Res Inst 35:23–33
Yokoyama I (1971) A model for the crustal deformations around volcanoes. J Phys Earth 19:199–207
Yokoyama I, Yamashita H, Watanabe H, Okada Hm (1981) Geophysical characteristics of dacite volcanism — The 1977–1978 eruption of Usu volcano. J Volcanol Geotherm Res 9:335–358
Yokoyama I, Maekawa T (1982) Precise gravity measurements on Miyakejima volcano in 1980. Rep 1st Joint Obs Miyakejima Volcano:23–30 (in Japanese)
Yokoyama I, Maekawa T (1984) Ground deformation and gravity change associated with the 1983 eruption of Miyakejima volcano. Bull Volcanol Soc Jpn 29:S130-S140 (in Japanese with English abstract)
Yokoyama I (1985) Volcanic processes revealed by geophysical observations of the 1977–1982 activity of Usu volcano, Japan. J Geodynamics 3:351–367
Yokoyama I (1986a) Crustal deformation caused by the 1914 eruption of Sakurajima volcano, Japan and its secular changes. J Volcanol Geotherm Res 30:283–302
Yokoyama I (1986b) Explosions, earthquake swarms and deformations: 1977–1982 activity of Usu volcano, Japan. Bull R Soc New Zealand 24:141–153
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Yokoyama, I. Microgravity and height changes caused by volcanic activity: Four. Bull Volcanol 51, 333–345 (1989). https://doi.org/10.1007/BF01056895
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF01056895