The National Research Institute for Earth Science and Disaster Prevention (NIED) developed volcano observation stations at the Kirishima volcanic group in 2010. The stations observed remarkable crustal deformation and seismic tremors associated with the Shinmoe-dake eruption in 2011. The major eruptive activity began with sub-Plinian eruptions (January 26) before changing to explosive eruptions and continuous lava effusion into the summit crater (from January 28). The observation data combined with GEONET data of GSI indicated a magma chamber located about 7 km to the northwest of Shinmoe-dake at about 10 km depth. The tiltmeter data also quantified detailed temporal volumetric changes of the magma chamber due to the continuous eruptions. The synchronized tilt changes with the eruptions clearly show that the erupted magma was supplied from the magma chamber; nevertheless, the stations did not detect clear precursory tilt changes and earthquakes showing ascent of magma from the magma chamber just before the major eruptions. The lack of clear precursors suggests that magma had been stored in a conduit connecting the crater and the magma chamber prior to the beginning of the sub-Plinian eruptions.

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In January 2011, the latest eruption began at Shinmoe-dake volcano, Japan, and lava accumulated in the crater. Differential interferometric synthetic aperture radar (DInSAR) observations after the end of main eruption indicated continuous uplift on the lava surface. We estimated the volume increase of lava, and the volume change rate has decreased exponentially. Results from long-term DInSAR processing indicate slow subsidence outside the crater. We interpret that this subsidence is caused by deflation of a shallow source located beneath the crater, which is a reaction to the extrusion of lava. Between November 2011 and May 2013, the total volume of extruded lava within the crater is estimated to be 6.7 ± 0.1 × 10 4 m 3 , which is comparable to the deflation volume of the shallow source. The system is not closed within the shallow source to the crater; thus, long-term lava extrusion can be explained by continuous injection from a deeper source to the shallow source.