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Earth, Planets and Space
Fig. 2 | Earth, Planets and Space

Fig. 2

From: Phreatic eruptions and deformation of Ioto Island (Iwo-jima), Japan, triggered by deep magma injection

Fig. 2

A comparison between earthquake activity and vertical movement of Ioto after 1977. a Monthly average of daily number of earthquakes counted at Motoyama. The numbers are counted at seismic stations of Japan Ministry of Defense around 0604 station of GSI before 1986 and at IJMV after 1992. The red curve shows the cumulative number of earthquakes. The red triangles and white triangles denote occurrence times of phreatic eruptions with and without precursors, respectively. b Vertical movement by campaign leveling and GPS surveys after 1977 at survey points near observation points where GNSS continuous observation is carried out. In the leveling survey up until 1995, average sea level as measured by the tide level gauge was taken as the reference height

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