(a) Temporal modeled volume changes of the magma chamber estimated from tiltmeter data during the period from January 23 to February 2, 2011. Total deflation volume is estimated from tiltmeter and GPS data. The percentage of total deflation volume from each eruption are shown. (b) Modeled deflation rate of the magma chamber by differentiation of the volume changes over time. (c) Temporal changes of 10-min-average seismometer amplitudes at KRMV and KRHV. The red and black arrows indicate the occurrence times of the sub-Plinian and smaller explosive eruptions, respectively.