Fig. 10
Schematic diagram of magma ascent and degassing processes of a 2011 and b 2017–18 eruptions of Shinmoedake volcano. The left axis shows depths below the summit of Shinmoedake. Expected density structure of crust around the Kirishima volcano based on a study by JMA (2013) is also shown. Densities and volumes of bubbles in mafic, felsic, 2011 and 2018 magmas at 125 MPa and 50 MPa estimated in this study are shown. Erupted-magma volumes for 26 January – 1 February 2011 (22–26 × 106 m3), 2 February – 26 September 2011 (< 0.2 × 106 m3), 6—9 March 2018 (15 × 106 m3) and 1 March—14 May 2018 (0.3 × 106 m3) and degassed-magma volumes for 2 February 2011 – 26 September 2012 (21 × 106 m3) and 10 March—13 October 2018 (8–9 × 106 m3; Table 5) are also shown. Volumes of mafic magmas injected to the magma chamber (18–21 × 106 m3 from 1 November 2009 to 25 January 2011, 11 × 106 m3 from 1 February to 1 December 2011, 11 × 106 m3 from 1 July 2017 to 1 March 2018 and 10 × 106 m3 from 10 March 2018 to 31 January 2019) are estimated from inflation of the magma chamber estimated from GPS observations (Nakao et al. 2013; JMA 2019a), assuming that the inflations were caused by injections of mafic magmas. Volumes of deflation of the magma chamber from 25 January to 1 February 2011 and from 1 to 10 March 2018 were estimated from GPS observations (Nakao et al. 2013; JMA 2019a). Volumes of the 2011 and 2018 magmas in the chamber estimated in this study (26–34 × 106 m3 of the 2011 magma just before the 2011 eruptions, 22–39 × 106 m3 of the 2011 magma in February 2011 to September 2012 and 22–35 × 106 m3 of the 2018 magma in July 2017; see Additional file 12 for details) are also shown. See text for details