1:45 PM - 2:00 PM
[SSS06-01] Geoscientific information about plate boundary along the Nankai Trough provided by the GNSS-A
Keywords:GNSS-A, Nankai Trough, SSE, plate boundary, coupling condition
After 2015, more important geoscientific suggestions were obtained from monitoring in the Nankai Trough. Yokota et al. [2016, Nature] showed undersea interseismic coupling condition. This observation result has been broadly applied to various geophysical studies while being modified [e.g., Nishimura et al., 2018, Gesphere; Noda et al., 2018, JGR] and constrains earthquake prediction research including numerical simulation and submarine drilling research.
In addition, recently, we improved the GNSS-A technology and upgraded observation frequency and precision [Yokota et al., 2017, Rep. Hydro. Ocean. Res; Yokota et al., 2018, MGR]. With the present observation ability, yearly time change of the amount of undersea crustal deformation was newly unclosed. This new version data suggests that there were longer-term sequences of slow slip events (SSEs) around strong coupling regions [Yokota and Ishikawa, this JpGU meeting].
These results provide several suggestions about property and condition on the plate boundary. The simple and biggest question is what is the reason for separating strong coupling and SSE conditions. Since the difference between the generation patterns of SSE and other slow earthquakes is also considered to be due to physical properties, some dominant factor can be assumed. Differences and similarities between deep and shallow SSEs are also important. What physical properties control the behaviors of deep and shallow SSEs?
For answering these questions, additional experiments and observations from many different viewpoints will be necessary. At the same time, continuous GNSS-A monitoring and upgrading its density and accuracy are required for understanding shallow coupling conditions and SSEs.