Volcanic Activity in Japan Monitored by the Japan Meteorological Agency Using Detected Precursory Phenomena
There are 76 potentially active volcanoes in Japan. The systematic volcanological work by the Japan Meteorological Agency (JMA) has been carried out since early 1960. The activity at 17 active volcanoes has been routinely monitored, and other volcanoes have been temporarily observed by mobile observation teams. During the period 1961–1985, 28 volcanoes erupted, and 17 volcanoes showed volcanic unrest such as earthquake swarms, fuming increase, etc. During these 25 years, therefore, there were an average of 5.5 eruptions a year, and 7.7 cases of volcanic unrest a year. According to the JMA observations up to now, the most clearly defined precursory event is the increase of seismicity before a volcanic eruption, but this pattern does not always occur. The next clearest precursor is the increase of intensity of fuming that has been observed at several volcanoes. It is difficult to predict smaller eruptions, as the clear precursor activity is lacking. In the cases of volcanoes which have been dormant for long periods, prior accumulation of relevant observational data is insufficient.
KeywordsVolcanic Eruption Japan Meteorological Agency Earthquake Swarm Volcanic Tremor Tectonic Earthquake
Unable to display preview. Download preview PDF.
- Volcanic activities in Japan during 1961–1985 compiled in this chapter are based on the following reports: Japan Meteorological Agency (1961–1986) Volcanological Bulletin, Vols. 1–24 (Nos. 1–4), Vol. 25 (Nos. 1–2). Japan Meteorological Agency (1985) Observation Report at Observatories during July–December, 1985 (in Japanese), unpublished.Google Scholar
- Omori F (1911) The Usu-san eruption and earthquake and elevation phenomena, Bull Imp Earthq Inv Com 5, 1:1–38, 3: 101–107Google Scholar
- Tanaka Y, Nishide N, Takahasi M (1984) Relation between the seismic activities around Miyakejima Volcano and the eruption of the volcano, Bulletin of the Volcanological Society of Japan-The 1983 Eruption of Miyakejima. Vol 29. Second Ser, Spec Iss, pp 45–54 (in Japanese with English abstract).Google Scholar
- Yokoyama I, Seino M (1979) Prediciton of development in the 1977–78 activities of Usu Volcano with consideration for energy. discharge. J Fac Sci, Hokkaido Univ, Ser VII (Geophysics), Vol 6, 1: 187–200Google Scholar