5:15 PM - 6:30 PM
[STT36-P03] Observing Crustal Deformation Using Interferometric Synthesis Aperture Rader and Estimating Magma Chamber Associating with the 2018 Eruption of Shinmoedake of Kirishima Volcanoes, Japan.
Keywords:Shinmoedake of Kirishima Volcanoes, InSAR, Mogi Model
Shinmoedake of Kirishima Volcanoes in Southern Kyushu, Japan is reported to be eruptive around March 2018. We investigated crustal deformations before (17th Oct. 2017 – 8th Feb. 2018), while (8th Feb. 2018 – 8th Mar. 2018) and after (8th Mar. 2018 – 7th Feb. 2019) of this eruption using Interferometric Synthetic Aperture Rader (InSAR). We also applied a spherical source deposited in a half-space model, called Mogi Model (Mogi, 1958), to presume the pressure source that caused eruptions as well as its latitude, longitude, depth and volume changes. To obtain fitting parameters, we considered Pearson’s X2 test and assumed the smallest magnitude would be valid. We used grid searching as hyperparameter optimisation when finding them.
The InSAR observations revealed that LOS were 2.41 [cm] in pre-eruptive, -3.75 [cm] in syn-eruptive and 3.93 [cm] in post-eruptive periods. These results were harmonic to baseline estimations of GNSS performed by JMA (2019) and GSI (2019).
Estimated volume changes were 0.37 [m3] in charging, -0.69 [m3] in discharging and 0.79 [m3] in re-charging process. We assumed the magma chamber that caused crustal deformations was located at the depth of 7.5 km at approximately 6 km away from the summit of Shinmoedake. These values are equivalent to JMA (2019), who obtained -0.66×107 [m3] (1st Mar. – 10th Mar. 2018), which applied Mogi Model to GNSS dataset. Since Shinmoedake is characteristic of its relatively spacious crater, NIED (2018) carried out SAR observations from 6th Mar. to 9th Mar. 2018 and determined the volume of accumulated ejecta was 1.32×107 [m3]. All the values were on the same order (107 [m3]).
Based on our analysis, we conclude that the 2011 events’ magma chamber (e.g. Kobayashi et al., 2011; Miyagi, Ozawa, and Kohno, 2013) could be attributed to 2018 events.
Acknowledgement
PALSAR level 1.0 data are shared amongst PIXEL and provided by JAXA under a cooperative research contract with ERI, Univ. of Tokyo. The ownership of PALSAR belongs to METI and JAXA.
References
GSI, Rep. Coordinating Comm. Prediction Volcan. Erupt., 132, 338-351, 2019. (in Japanese)
JMA, Doc. Coordinating Comm. Prediction Volcan. Erupt., 144, 89-101, 2019. (in Japanese)
Kobayashi, T. et al., Bull. GSI, 121, 195-201, 2011. (in Japanese)
Miyagi, Y., Ozawa, T. and Kohno, Y., Kazan (Bull. Volcanol. Soc. Japan), 58(2),341-351, 2013. (in Japanese)
Mogi, K., Bull. Earthq. Res. Inst. Univ. Tokyo, 36, 99-134, 1958.
NIED, https://www.bosai.go.jp/info/saigai/2017/pdf/20180309_01.pdf, 2018. (in Japanese)
The InSAR observations revealed that LOS were 2.41 [cm] in pre-eruptive, -3.75 [cm] in syn-eruptive and 3.93 [cm] in post-eruptive periods. These results were harmonic to baseline estimations of GNSS performed by JMA (2019) and GSI (2019).
Estimated volume changes were 0.37 [m3] in charging, -0.69 [m3] in discharging and 0.79 [m3] in re-charging process. We assumed the magma chamber that caused crustal deformations was located at the depth of 7.5 km at approximately 6 km away from the summit of Shinmoedake. These values are equivalent to JMA (2019), who obtained -0.66×107 [m3] (1st Mar. – 10th Mar. 2018), which applied Mogi Model to GNSS dataset. Since Shinmoedake is characteristic of its relatively spacious crater, NIED (2018) carried out SAR observations from 6th Mar. to 9th Mar. 2018 and determined the volume of accumulated ejecta was 1.32×107 [m3]. All the values were on the same order (107 [m3]).
Based on our analysis, we conclude that the 2011 events’ magma chamber (e.g. Kobayashi et al., 2011; Miyagi, Ozawa, and Kohno, 2013) could be attributed to 2018 events.
Acknowledgement
PALSAR level 1.0 data are shared amongst PIXEL and provided by JAXA under a cooperative research contract with ERI, Univ. of Tokyo. The ownership of PALSAR belongs to METI and JAXA.
References
GSI, Rep. Coordinating Comm. Prediction Volcan. Erupt., 132, 338-351, 2019. (in Japanese)
JMA, Doc. Coordinating Comm. Prediction Volcan. Erupt., 144, 89-101, 2019. (in Japanese)
Kobayashi, T. et al., Bull. GSI, 121, 195-201, 2011. (in Japanese)
Miyagi, Y., Ozawa, T. and Kohno, Y., Kazan (Bull. Volcanol. Soc. Japan), 58(2),341-351, 2013. (in Japanese)
Mogi, K., Bull. Earthq. Res. Inst. Univ. Tokyo, 36, 99-134, 1958.
NIED, https://www.bosai.go.jp/info/saigai/2017/pdf/20180309_01.pdf, 2018. (in Japanese)