11:00 AM - 1:00 PM
[SGD01-P02] Spatiotemporal variation in interplate coupling of the Nankai trough revealed by GNSS-A observation
Keywords:GNSS-A, Seafloor geodesy, Nankai trough earthquake
The Japan Coast Guard (JCG) has been conducting regular observations of seafloor crustal movement using GNSS-A technique to collect data for monitorting the interplate coupling condition along the Japan Trench and the Nankai Trough.
At the plate boundary, various slow earthquakes have been detected by various seismic and geodetic observation networks. To mitigate future earthquake disasters, it is important to understand their spatiotemporal characteristics. When anomalous geophysical phenomena are observed in the Nankai Trough region, the Japan Meteorological Agency will issue the Nankai Trough earthquake information to prepare the disaster. Therefore, monitoring the condition of interplate coupling is an important key to earthquake disaster prevention. GNSS-A observation provides important data for monitoring the interplate coupling condition, by directly measuring crustal movement of the seafloor just above the source region of megathrust earthquakes.
The present GNSS-A observations operated by JCG are carried out by campaign observations by manned vessels. Therefore, annual frequency of the observations is 4-6 times which is difficult to detect short-term phenomena such as slow slip events. However, the accumulation of observation data over the past 10 years has enabled us to detect the temporal variation of the interplate coupling, and to reveal the spatial distribution of slow earthquakes and srtong coupling region. In this presentation, we will report on the results of estimating the temporal variation in the interplate coupling obtained from GNSS-A observation time series.
To estimate the interplate slip, simple calculations in elastic half-space homogeneous have been widely used. This approximation is good for estimating a narrow region. However, the data distribution is spread over a wide region from land to the seafloor when using the seafloor data obtained by GNSS-A observations. In this case, a more realistic earth model is needed for accurate estimation. Recently, Hori et al. (2021) released a library for the Green's functions based on a numerical model that reflects realistic topography and subsurface structure of the Earth. In this presentation, we will also report on the results using this Green's functions.
At the plate boundary, various slow earthquakes have been detected by various seismic and geodetic observation networks. To mitigate future earthquake disasters, it is important to understand their spatiotemporal characteristics. When anomalous geophysical phenomena are observed in the Nankai Trough region, the Japan Meteorological Agency will issue the Nankai Trough earthquake information to prepare the disaster. Therefore, monitoring the condition of interplate coupling is an important key to earthquake disaster prevention. GNSS-A observation provides important data for monitoring the interplate coupling condition, by directly measuring crustal movement of the seafloor just above the source region of megathrust earthquakes.
The present GNSS-A observations operated by JCG are carried out by campaign observations by manned vessels. Therefore, annual frequency of the observations is 4-6 times which is difficult to detect short-term phenomena such as slow slip events. However, the accumulation of observation data over the past 10 years has enabled us to detect the temporal variation of the interplate coupling, and to reveal the spatial distribution of slow earthquakes and srtong coupling region. In this presentation, we will report on the results of estimating the temporal variation in the interplate coupling obtained from GNSS-A observation time series.
To estimate the interplate slip, simple calculations in elastic half-space homogeneous have been widely used. This approximation is good for estimating a narrow region. However, the data distribution is spread over a wide region from land to the seafloor when using the seafloor data obtained by GNSS-A observations. In this case, a more realistic earth model is needed for accurate estimation. Recently, Hori et al. (2021) released a library for the Green's functions based on a numerical model that reflects realistic topography and subsurface structure of the Earth. In this presentation, we will also report on the results using this Green's functions.