10:45 AM - 12:15 PM
[SGD02-P06] Spatio-temporal evolution of interplate slip in southwestern Japan since 2018
Keywords:long-term slow slip, Hyuga-nada Sea, Kii-channel
Abstract
Interplate slip along the Nankai Trough since 2018 was estimated using GNSS data in southwestern Japan. As a result, it is estimated that the SSE occurred in the northern Hyuga-nada around July 2018, and that the SSE area spread to the Bungo Channel from October 2018 to mid-2019. Mw is estimated to be around 7.0. From around the end of 2018 to the beginning of 2019, an SSE occurred in southern Hyuga-nada with about Mw6.0. An SSE occurred in central Shikoku from early 2019 and continues until December 2022. An energy of about Mw 6.5 is estimated. The long-term SSE in central Shikoku appears to be synchronized with the short-term SSE in northwestern Shikoku. An SSE occurred in the Kii Channel from around April 2019 and ended in 2022. Mw was estimated to be about 6.3. From mid-2020 to mid-2021, an SSE occurred in the southern Hyuga-nada, releasing energy of about Mw6.5. Off the coast of Tanegashima, an afterslip occurred after the 2019 Tanegashima earthquake, releasing energy of about Mw6.6.
Introduction
Since 2018, transient crustal deformation has been detected in the area from Shikoku to Kyushu along the Nankai Trough. Previous studies did not consider the postseismic deformation after the 2011 Tohoku earthquake and the 2016 Kumamoto earthquake. In this study, the effects of the 2011 Tohoku earthquake and the 2016 Kumamoto earthquake were corrected as viscoelastic deformation.
Analysis method
The viscoelastic deformations of the 2011 Tohoku earthquake and the 2016 Kumamoto earthquake are corrected from the results of Suito (2017a) and Suito (2017b), and the trend for 2006-2009 is removed from the original data. The east-west, north-south, and top-bottom components of 240 GPS stations were used for time-dependent inversion. The plate shape is represented by triangular elements based on Hirose (2008). The analysis period was from January 2018 to December 2022.
Conclusion
Regarding the slippage of the Bungo Channel, the results are consistent with previous studies. The SSE in central Shikoku began around 2019 and is still ongoing as of 2023. It is estimated that the long-term SSE in central Shikoku is synchronized with the occurrence of short-term SSE in northwest Shikoku. The estimated moment was estimated to be about Mw6.5. The Kii Channel SSE begin around 2019 and ended in 2022. Mw was estimated to be around 6.3. From mid-2020 to mid-2021, the SSE in the southern Hyuga-nada released an energy of about Mw6.5. After the 2019 Tanegashima earthquake (Mw6.4), two short-term SSE occurred off the coast of Tanegashima, and a total of about Mw6.6 energy was released.
Interplate slip along the Nankai Trough since 2018 was estimated using GNSS data in southwestern Japan. As a result, it is estimated that the SSE occurred in the northern Hyuga-nada around July 2018, and that the SSE area spread to the Bungo Channel from October 2018 to mid-2019. Mw is estimated to be around 7.0. From around the end of 2018 to the beginning of 2019, an SSE occurred in southern Hyuga-nada with about Mw6.0. An SSE occurred in central Shikoku from early 2019 and continues until December 2022. An energy of about Mw 6.5 is estimated. The long-term SSE in central Shikoku appears to be synchronized with the short-term SSE in northwestern Shikoku. An SSE occurred in the Kii Channel from around April 2019 and ended in 2022. Mw was estimated to be about 6.3. From mid-2020 to mid-2021, an SSE occurred in the southern Hyuga-nada, releasing energy of about Mw6.5. Off the coast of Tanegashima, an afterslip occurred after the 2019 Tanegashima earthquake, releasing energy of about Mw6.6.
Introduction
Since 2018, transient crustal deformation has been detected in the area from Shikoku to Kyushu along the Nankai Trough. Previous studies did not consider the postseismic deformation after the 2011 Tohoku earthquake and the 2016 Kumamoto earthquake. In this study, the effects of the 2011 Tohoku earthquake and the 2016 Kumamoto earthquake were corrected as viscoelastic deformation.
Analysis method
The viscoelastic deformations of the 2011 Tohoku earthquake and the 2016 Kumamoto earthquake are corrected from the results of Suito (2017a) and Suito (2017b), and the trend for 2006-2009 is removed from the original data. The east-west, north-south, and top-bottom components of 240 GPS stations were used for time-dependent inversion. The plate shape is represented by triangular elements based on Hirose (2008). The analysis period was from January 2018 to December 2022.
Conclusion
Regarding the slippage of the Bungo Channel, the results are consistent with previous studies. The SSE in central Shikoku began around 2019 and is still ongoing as of 2023. It is estimated that the long-term SSE in central Shikoku is synchronized with the occurrence of short-term SSE in northwest Shikoku. The estimated moment was estimated to be about Mw6.5. The Kii Channel SSE begin around 2019 and ended in 2022. Mw was estimated to be around 6.3. From mid-2020 to mid-2021, the SSE in the southern Hyuga-nada released an energy of about Mw6.5. After the 2019 Tanegashima earthquake (Mw6.4), two short-term SSE occurred off the coast of Tanegashima, and a total of about Mw6.6 energy was released.