DInSAR及びGPSによって検出された霧島山・新燃岳2011年噴火に伴う地殻変動

概要

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Shinmoe-dake in the Kirishima volcano group located in southwestern Japan started to erupt on January 19, 2011 and the eruption developed to Sub-Plinian eruptionson January 26 and 27. Crustal deformations associated with the eruption, including pre-eruptive inflation, co-eruptive deflation, and post-eruptive inflation, were detected by DInSAR and GPS measurements. Geodetic information revealed by two different methods compensate each other and exhibit good agreement. The centers of these deformations for each period almost overlap and are located about 5km west-northwest of the Shinmoe-dake crater. Assuming that the deformation source indicating magma chamber at a depth of 7.5km was fixed at the same location and depth, volumes of the source are estimated to have increased 1.7×10^7m^3 for the pre-eruptive period, decreased 1.5×10^7m^3 for the co-eruptive period, and increased 8.0×10^6m^3 for the post-eruptive period. The co-eruptive volume decrease is comparable to the pre-eruptive volume increase and the emitted volume. However, the post-eruptive volume increase is obviously small and ceased after December 2011. The magma chamber has now returned to about 50% of the eruptive volume of the 2011 eruption. If a volume increase start again at a similar rate, it will be about 10 months until the next 2011-size eruption.
2013-06-28