# Precise Positioning of BDS, BDS/GPS: Implications for Tsunami Early Warning in South China Sea
## 2 Real-Time Kinematic Precise Positioning Performance of BDS in South-East Asia
This rupture scenario was selected due to its highest impact potential for the south Chinese coast. The accepted source model has a magnitude of Mw = 8.0 with the central point located at 119.8\({}^{\circ}\) E/18.7\({}^{\circ}\) N. The length is 180 km, the width 35 km, and the strike and the dip angles of the rupture plane are fixed to 35 and 20 degrees. The only difference with the original E2 rupture model is in slip distribution: we use a bell-shaped distribution rather than a uniform slip. The rupture plane consists of 75 sub-faults with a symmetry maximum at the slip center, and with the rake angles varying between 80 and 100 degrees. We use code QSSP developed by [PERSON] [42] to calculate synthetic displacement waveforms at stations of our virtual GNSS-array. With respect to the Earth model, in this study, the average global 1-D reference earth model AK135Q [43] is adopted. Figure 3 demonstrates simulated displacement waveforms at the selected station B1 (see virtual array in Figure 4a). To make our test even more realistic, we contaminate synthetic co-seismic displacements with a typical real-time BDS and BDS/GPS processing noises derived from a random segment of the GMSD (or SIN1) residual displacement time series, and the corresponding \"noisy\" displacements are also shown at Figure 3. These \"noisy\" displacements will be used for source inversion. Figure 4a presents an overview of our forward rupture model: It shows assumed slip distribution together with the corresponding co-seismic vertical deformation as well as horizontal static offsets at the virtual BDS/GPS network. Figure 2: TPP solutions of BDS, GPS and BDS/GPS at stationary station GMSD on 30 December 2013. Additionally shown is the corresponding PDOP, which specifies the effect of navigation satellite constellation geometry on positional precision. Note that, since the station did not move, the above graphs can be used to evaluate the expected uncertainty of TPP displacements. Figure 4: _Cont._  
Figure 3: Simulated displacement waveforms in forward-model scenario (rupture E2, see text for description). Waveforms are shown at one selected virtual GNSS-station placed at the Luzon Island (contoured triangle on Figure 4a). Black lines represent original kinematic simulations; colored lines represent the simulations after an addition of typical TPP processing noise (Section 2). “Noisy” displacements will be used for source inversion. Based on the suggested rupture, the corresponding tsunami scenario was simulated (Figure 5) using the _easyWave_ wave propagation code [20]. _easyWave_ follows the numerical algorithm by [PERSON] _et al._[44] for the simulation of linear long-wave propagation in spherical coordinates. Tsunami propagation was computed on the 1 arc minute GEBCO (General Bathymetric Chart of the Oceans) bathymmetric grid [45], and the sea-level heights at offshore positions were projected to the  
Figure 4: (**a**) Assumed slip distribution (colored dots) and correspondent co-seismic surface deformation for an event with a magnitude of Mw = 8.0 rupturing along the Northern Manila mega-thrust: our forward-model scenario. Red arrows show horizontal displacements computed at the virtual BDS/GPS network (black triangles). The yellow triangle (B1) marks the station from Figure 3; (**b**) Colored dots represent slip distribution as inverted from the simulated BDS-displacements (note, synthetic BDS-displacements include real-time processing noise). Additionally shown is the resulting vertical deformation; (**c**) Same as (**b**), but for the inversion of the joint BDS/GPS displacements. coast using [PERSON]'s amplification law [46]. As expected, due to the predominantly SW-NE orientation of the rupture, main tsunami energy is radiated towards the southeastern coast of China, between the cities of Hong Kong and Shantou (Figure 5). Expected maximum tsunami wave heights may reach up to 10 m at the west coast of the Luzon Island.