5:15 PM - 6:45 PM
[SGD02-P05] 2023 Boso SSE
Keywords:SSE, Boso
Abstract
Transitional crustal movements were detected off the coast of the Boso Peninsula over several days from the end of November 2023. When the slip on the Philippine Sea plate was estimated by time-dependent inversion, an interplate slip of about 2 cm was estimated in the area of the conventional SSE off the coast of Boso. The estimated Mw is small at 6.2, which may be different from the SSE that has traditionally occurred every 5-6 years, and there is a possibility that SSEs of conventional scale occur in the future.
Introduction
In the Boso area, SSEs have occurred at intervals of about 5 to 6 years. Five years have passed since the 2018 SSE, and the next SSE was expected to occur. Under such circumstances, transitional crustal movements occurred over several days in November 2023. In this study, we estimated the slip on the Philippine Sea plate boundary based on the transitional crustal deformation in November 2023.
analysis method
The primary trend and periodicity for 2020-2022 were estimated and removed from the original data. The east-west, north-south, and vertical components of the 40 GNSS observation points were used for time-dependent inversion. The plate shape of the Philippine Sea Plate is expressed by a rectangular element that is a combination of two triangular elements based on Hirose (2008). The analysis period was from September 2023 to December 2023. The slip angle was not fixed, but estimated in the range of 10-70 degrees clockwise from the east. The spatiotemporal hyperparameters are estimated using the maximum likelihood method. The analysis was performed taking into account the common mode errors, and the influence of fixed points is considered to be relatively small.
conclusion
From the time-series data, transitional crustal deformation in the east-southeast direction of approximately 5 mm was detected at several points on the Boso Peninsula. The time-dependent inversion results estimate a slip of about 2 cm in the conventional slip area of the Boso Peninsula SSE. The estimated Mw is 6.2, which is a much smaller value than the conventional Boso SSE, which is around 6.6-6.8. When the slip angle is estimated under east and south conditions, the slip area is estimated to have peaks in two areas, east and south of the Boso Peninsula. Since the scale is much smaller than previous SSEs, there is a possibility that it is a different type of event from the Boso SSE, which has a 5-6 year cycle, and this event is not the end, and there is a possibility that SSEs of conventional scale will occur in the future.
Transitional crustal movements were detected off the coast of the Boso Peninsula over several days from the end of November 2023. When the slip on the Philippine Sea plate was estimated by time-dependent inversion, an interplate slip of about 2 cm was estimated in the area of the conventional SSE off the coast of Boso. The estimated Mw is small at 6.2, which may be different from the SSE that has traditionally occurred every 5-6 years, and there is a possibility that SSEs of conventional scale occur in the future.
Introduction
In the Boso area, SSEs have occurred at intervals of about 5 to 6 years. Five years have passed since the 2018 SSE, and the next SSE was expected to occur. Under such circumstances, transitional crustal movements occurred over several days in November 2023. In this study, we estimated the slip on the Philippine Sea plate boundary based on the transitional crustal deformation in November 2023.
analysis method
The primary trend and periodicity for 2020-2022 were estimated and removed from the original data. The east-west, north-south, and vertical components of the 40 GNSS observation points were used for time-dependent inversion. The plate shape of the Philippine Sea Plate is expressed by a rectangular element that is a combination of two triangular elements based on Hirose (2008). The analysis period was from September 2023 to December 2023. The slip angle was not fixed, but estimated in the range of 10-70 degrees clockwise from the east. The spatiotemporal hyperparameters are estimated using the maximum likelihood method. The analysis was performed taking into account the common mode errors, and the influence of fixed points is considered to be relatively small.
conclusion
From the time-series data, transitional crustal deformation in the east-southeast direction of approximately 5 mm was detected at several points on the Boso Peninsula. The time-dependent inversion results estimate a slip of about 2 cm in the conventional slip area of the Boso Peninsula SSE. The estimated Mw is 6.2, which is a much smaller value than the conventional Boso SSE, which is around 6.6-6.8. When the slip angle is estimated under east and south conditions, the slip area is estimated to have peaks in two areas, east and south of the Boso Peninsula. Since the scale is much smaller than previous SSEs, there is a possibility that it is a different type of event from the Boso SSE, which has a 5-6 year cycle, and this event is not the end, and there is a possibility that SSEs of conventional scale will occur in the future.