[SGD02-P11] Performance assessment of the GNSS carrier phase to fault slip approach and its feasibility for seismic monitoring
Here we applied the PTS method to the sequence of the 2011 Tohoku-Oki earthquake. In the analysis, we used both precise orbit which is provided by International GNSS Service (IGS) and broadcast orbit submitted from satellite without any network connection. As a result, in the case of IGS orbit, we obtained coseismic slip distribution of the mainshock that well agree with estimation result using conventional positioning analysis time series, such as shown by Iinuma et al. (2011). Although the estimated moment magnitude 8.8 is slight smaller than those by previous studies, calculated displacement field shows good consistency with that derived from positioning analysis. Moreover, we could also detect coseismic slip of subsequent two large aftershocks that occurred in the off Iwate and the off Ibaraki region. These results suggest that we can make use of the PTS method for continuous seismic monitoring in subduction zone. In case of using broadcast orbit, the long-term stability of the estimated slip time series become much worse. However, if we focus on their relative change within 10 minutes after the earthquakes, we can obtain very similar slip behaviors compared to using IGS orbit. Differences between the slip distributions of two cases became just around one meter or less, which is smaller than the estimated standard deviation of fault slip. These results indicate that the PTS method can be useful as a supplementary system of current monitoring system, which does not depend on any external information.
In the presentation, we will describe detail of these results. Additionally, we will also evaluate O-C fitness and accuracy of parameter separation quantitatively in the dimension of carrier phase, which is used as observation in PTS analysis. Then, we will discuss characteristics of the PTS and future works for refined seismic monitoring using this method.