5:15 PM - 6:30 PM
[SCG49-P03] Geometry of the Moho and three-dimensional P-wave velocity structure model in the Japan Sea based on active-source seismic survey data
Keywords:Japan Sea, Moho, Crustal structure, Seismic survey
In the last two decades, data acquisition for crustal structure exploration has advanced owing to the increased accuracy and operational efficiency of ocean bottom seismographs (OBS) and active-source seismic survey systems. As a result, the spatial resolutions of the obtained crustal structures have increased, and discussing the heterogeneity of the structure has become possible. The crustal structural study of the Japan Sea is no exception; it has advanced in recent years. Through several research projects, seismic surveys using OBSs and multichannel seismic reflection (MCS) surveys have been carried out from off the west coast of Hokkaido to off the Sanin region.
In this study, we constructed the geometry of the Moho and developed a three-dimensional P-wave velocity structure model for the southeastern half of the Japan Sea (eastern margin of the Japan Sea to off Sanin) using the active-source seismic survey data. We employed Schlumberger's software (Petrel) to build the model based on the seismic survey data acquired by the “Multidisciplinary research project for the construction of fault model in the high strain rate zone” and the “Integrated Research Project on Seismic and Tsunami Hazards Around the Sea of Japan,” as well as those acquired in the 2000s in the off Chuetsu, Yamato Basin, and off Tottori (Sato et al., 2006; Nakahigashi et al., 2012; Nakahigashi et al., 2013). In addition, the results of the crustal structural surveys conducted prior to 2000 were included in the model when the position and velocity structure of the survey lines could be digitized. First, to study the spatial geometry of Moho, we used the gravity data to spatially connect and correct the Moho based on its depth estimated by seismic data. The Gravity Magnetic Modeling and Inversion toolkit, a plugin for Petrel's gravity inversion (Priezzhev, 2014), was used to utilize the gravity data. The used gravity data was the grid data, including both land and marine areas, from the Gravity Database of Japan (Geological Survey of Japan, 2013), and the density structure was adapted from the functional relationships between velocity and density by Ludwig et al. (1970).
The three-dimensional P-wave velocity structure model was developed as follows. The top surface of the model was set to 3 km above the sea level in the air and the bottom surface to 40 km below the sea level with a grid size of 1 km × 1 km. Furthermore, four surfaces were set in the model: the sea surface (0 km), submarine topography, sediment basement, and Moho, and a constant velocity were input for the atmospheric and seawater layers. The area from the submarine topography to the bottom of the model was calculated based on the P-wave velocity structure analyzed by the active-source seismic survey data.
We present the obtained preliminary results of Moho’s geometry and the 3-D P-wave velocity structure model for the Japan Sea.
In this study, we constructed the geometry of the Moho and developed a three-dimensional P-wave velocity structure model for the southeastern half of the Japan Sea (eastern margin of the Japan Sea to off Sanin) using the active-source seismic survey data. We employed Schlumberger's software (Petrel) to build the model based on the seismic survey data acquired by the “Multidisciplinary research project for the construction of fault model in the high strain rate zone” and the “Integrated Research Project on Seismic and Tsunami Hazards Around the Sea of Japan,” as well as those acquired in the 2000s in the off Chuetsu, Yamato Basin, and off Tottori (Sato et al., 2006; Nakahigashi et al., 2012; Nakahigashi et al., 2013). In addition, the results of the crustal structural surveys conducted prior to 2000 were included in the model when the position and velocity structure of the survey lines could be digitized. First, to study the spatial geometry of Moho, we used the gravity data to spatially connect and correct the Moho based on its depth estimated by seismic data. The Gravity Magnetic Modeling and Inversion toolkit, a plugin for Petrel's gravity inversion (Priezzhev, 2014), was used to utilize the gravity data. The used gravity data was the grid data, including both land and marine areas, from the Gravity Database of Japan (Geological Survey of Japan, 2013), and the density structure was adapted from the functional relationships between velocity and density by Ludwig et al. (1970).
The three-dimensional P-wave velocity structure model was developed as follows. The top surface of the model was set to 3 km above the sea level in the air and the bottom surface to 40 km below the sea level with a grid size of 1 km × 1 km. Furthermore, four surfaces were set in the model: the sea surface (0 km), submarine topography, sediment basement, and Moho, and a constant velocity were input for the atmospheric and seawater layers. The area from the submarine topography to the bottom of the model was calculated based on the P-wave velocity structure analyzed by the active-source seismic survey data.
We present the obtained preliminary results of Moho’s geometry and the 3-D P-wave velocity structure model for the Japan Sea.