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[SVC38-23] Inflation Event of Zao Volcano in 2015
Keywords:Volcano, deformation, Pressure source
Figure 1 demonstrate the horizontal and vertical movement around Zao, respectively, from Jan. to Jun. of 2015. The black arrows show the observed ground movement. The radial pattern of movement around the summit of the volcano is clearly seen and the upheaval indicated by the black bars also centered around the summit. These characteristics of deformation can be modeled by a infinitesimal pressure source underground (so called Mogi model). We tried inversion analyses to find its location and magnitude. It is located about 0.8 km east of the crater lake with depth of about 5.6 km, and the volumetric change equivalent to the pressure change is 3.8 x 106m3. The calculated displacements are shown in the figure by white arrows and bars.
Comparing the hypocenter map, the pressure source is located just above the deep low frequency earthquakes cluster. This suggests that the pressure source might be activated by geothermal heat supplied by magma or fluid. Ogawa et al. (2014) found a conductive zone beneath Zao volcano deeper than about 5km and this may support our result.