4:15 PM - 4:30 PM
[SCG61-10] GNSS strain rate field and factors contributing to topographic evolution of the Tsugaru Strait and its surroundings
Keywords:Strain rate field, Tsugaru Strait, Topographic evolution, GNSS
The Tsugaru Strait is a channel separating Honshu and Hokkaido. The formation of the Tsugaru Strait is considered to be the result of a complex interaction of several factors, including crustal deformation, erosion, and sea level change. However, the extent to which these factors contribute to topographic evolution remains unclear. Recent technological advancements have facilitated the accumulation of geodetic data, particularly high-density and high-precision crustal deformation data, now available through SoftBank's dense GNSS observation network. In this study, we investigate the geodetic factors contributing to the evolution of large- and small-scale topographic features in the Tsugaru Strait and examine their relationship to the strait’s formation processes.
We used GNSS stations of GEONET (operated by Geospatial Information Authority of Japan), International GNSS Service (IGS), and SoftBank Corporation. We used the results of the analysis of the Nevada Geodetic Laboratory for GEONET and IGS. For SoftBank, we used the routine analysis results of Tohoku University. We used stations distributed across the central to northern parts of the Tohoku region and the southwestern part of Hokkaido, covering two years from January 1, 2022, to December 31, 2023. Using these data, we estimated the strain rate field.
The estimated strain rate field indicates a tendency of east-west shortening in the Tohoku region and northwest-southeast shortening in Hokkaido. Notably, significant negative dilatation rates are observed in the Ou Backbone range, the Ishikari lowlands, and the volcanic front extending to the northeast. In contrast, no significant shortening is observed from north of Aomori to southwest Hokkaido, although the area is also on the volcanic front. Moreover, positive dilatation rates are observed around active volcanoes such as Mts. Usu, Tarumae, Komagatake in Hokkaido, and Mt. Iwate indicate the expansion of the volcanic edifices associated with volcanic activity.
The Ou backbone mountains, with elevations ranging from 1,000 to 2,000 m, end near Mt. Hakkoda in Aomori Prefecture, and relatively low hills and lowlands are distributed north of this area. Moreover, the sea area in the lowlands, represented by the Tsugaru Strait, Mutsu Bay, and Uchiura Bay, show clear elevation contrast with the Backbone Range. In our results, the strain rate is lower in these areas, indicating a correspondence between the large-scale topographic trends and the strain rate field. Therefore, the long-term strain accumulation may have played a role in developing large-scale topographic features. On the other hand, the distribution of land and sea areas in lower elevation regions may have been influenced by shorter-wavelength deformation, including active volcanoes, active faults, and active folds.
We would like to study the geomorphological and geological factors that contribute to the area's topographic evolution in the future.
Acknowledgments
GNSS data from the SoftBank observation network were provided by SoftBank Corp. and ALES Corp. to the “Consortium to utilize the SoftBank original reference sites for Earth and Space Science” under the associated contract. Moreover, we used the routine analysis results of Tohoku University for SoftBank stations. We also used the analysis results of the Nevada Geodetic Laboratory analysis for GEONET and IGS. We would like to appreciate these relevant.
We used GNSS stations of GEONET (operated by Geospatial Information Authority of Japan), International GNSS Service (IGS), and SoftBank Corporation. We used the results of the analysis of the Nevada Geodetic Laboratory for GEONET and IGS. For SoftBank, we used the routine analysis results of Tohoku University. We used stations distributed across the central to northern parts of the Tohoku region and the southwestern part of Hokkaido, covering two years from January 1, 2022, to December 31, 2023. Using these data, we estimated the strain rate field.
The estimated strain rate field indicates a tendency of east-west shortening in the Tohoku region and northwest-southeast shortening in Hokkaido. Notably, significant negative dilatation rates are observed in the Ou Backbone range, the Ishikari lowlands, and the volcanic front extending to the northeast. In contrast, no significant shortening is observed from north of Aomori to southwest Hokkaido, although the area is also on the volcanic front. Moreover, positive dilatation rates are observed around active volcanoes such as Mts. Usu, Tarumae, Komagatake in Hokkaido, and Mt. Iwate indicate the expansion of the volcanic edifices associated with volcanic activity.
The Ou backbone mountains, with elevations ranging from 1,000 to 2,000 m, end near Mt. Hakkoda in Aomori Prefecture, and relatively low hills and lowlands are distributed north of this area. Moreover, the sea area in the lowlands, represented by the Tsugaru Strait, Mutsu Bay, and Uchiura Bay, show clear elevation contrast with the Backbone Range. In our results, the strain rate is lower in these areas, indicating a correspondence between the large-scale topographic trends and the strain rate field. Therefore, the long-term strain accumulation may have played a role in developing large-scale topographic features. On the other hand, the distribution of land and sea areas in lower elevation regions may have been influenced by shorter-wavelength deformation, including active volcanoes, active faults, and active folds.
We would like to study the geomorphological and geological factors that contribute to the area's topographic evolution in the future.
Acknowledgments
GNSS data from the SoftBank observation network were provided by SoftBank Corp. and ALES Corp. to the “Consortium to utilize the SoftBank original reference sites for Earth and Space Science” under the associated contract. Moreover, we used the routine analysis results of Tohoku University for SoftBank stations. We also used the analysis results of the Nevada Geodetic Laboratory analysis for GEONET and IGS. We would like to appreciate these relevant.