Fig. 8

Comparison between residuals for the best-fit FE model and the simulated deformations presumably caused by the sources proposed in Takagi and Onizawa (2016). a, d Residual images obtained by subtraction of the optimal FE model predictions (Fig. 5) from decomposed EW and UD component during the period between the end of September 2014 and the end of July 2015 (Fig. 4). Residuals remain in the close vicinity of the deflation center, where deformation might be complicated. For example, fractured and soft medium near the eruptive vents could amplify the deformation magnitude locally, or complex geometry of the deformation source, that is, not spheroidal source, could contribute to the locally amplified deformation. b, e Simulated deformations caused by the deflation source at 1 km depth. c, f Simulated deformations caused by the source at 3 km depth