Feasibility of the GNSS carrier phase to fault slip approach for estimation of coseismic and postseismic slip phenomena: a case study of the 2011 Tohoku-Oki sequence
Abstract
Deformation monitoring method with broadband sensitivity is essential for understanding total process of earthquake cycle. However, current GNSS analysis show pretty low precision for the time scale around hour to half a day due to difficulty about separation of unknown parameters. Additionally, positioning analysis requires large computational cost. Here we show the possibility of deformation monitoring using another approach, GNSS carrier phase to fault slip approach. This method, which we call PTS (Phase To Slip) inverts fault slip directly from GNSS carrier phase change via Green's function without positioning. Thus we can handle error of fault slip and other unknown like tropospheric delay in parallel and consider their precise separation more reasonably. Moreover, we can reduce computational costs for analysis dramatically.
In this study, first we examined capability of PTS for coseismic event. We applied PTS to the sequence of 2011 Tohoku-Oki earthquake including its mainshock and two large aftershocks. As a result, PTS estimated large thrust slip around off Miyagi region just after the time of mainshock. After that, PTS could also detect coseismic slip of the largest aftershock in off Ibaraki region. Obtained slip distribution and magnitude is generally consistent with results using conventional GNSS analysis such as Iinuma et al. (EPS, 2011). Our results indicate that PTS can detect coseismic slip phenomena occur in subduction zone to some extent. On the other hand, we also revealed that it is difficult to detect both seismic and aseismic phenomena with same structure of observation equation, and hyperparameter controlling inversion. If we use PTS for longer time scale, we need further consideration about its model setting and control parameter. In the presentation, we will describe advanced results of our research including application of PTS for early afterslip process and detailed discussion about how to improve precision and stability of parameter estimation using PTS.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.T11A..03T
- Keywords:
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- 1209 Tectonic deformation;
- GEODESY AND GRAVITY;
- 1294 Instruments and techniques;
- GEODESY AND GRAVITY;
- 8118 Dynamics and mechanics of faulting;
- TECTONOPHYSICS;
- 8120 Dynamics of lithosphere and mantle: general;
- TECTONOPHYSICS