[S-VC28] Active Volcanism

[SVC28-P20] Estimate of magma supply beneath Aira caldera during the last 10 years based on ground deformation observation and amount of volcanic ejecta

*Daisuke Miki¹, Tomoki Tsutsui¹, Masato Iguchi¹ (1.Sakurajima Volcano Research Center, Disaster Prevention Research Institute, Kyoto University)

Keywords:Aira caldera, ground deformation, magma supply

We applied a composite analysis of spherical pressure source at around Aira caldera, Kyushu Japan. Horizontal displacements obtained from GNSS observations and vertical displacements from leveling survey, during 2017 to 2019, were used for the analysis. A volume increase source of 15.2 × 10⁶ m³ was estimated at a depth of 11.2 km near the central part of Aira Caldera. The volume change during the last 10 years was calculated based on the estimated location of the pressure source beneath Aira caldera and change in horizontal distance between MAKI and YOSI, which crosses the central part of Aira caldera from east to west. The amount of magma supplied to Aira caldera was estimated by adding the amount of volcanic ash ejected from Sakurajima volcano, to volume change of pressure source. Estimated magma supply during the last 10 years are 70 × 10⁶ m³ and 93 × 10⁶ m³, respectively, assuming equivalent densities of 2500 kg/m³ and 1000 kg/m³. The average magma supply rate is close to the 10 × 10⁶ m³/yr obtained in previous studies.