## 3 Result and Discussion
### Displacement Rate
\begin{table}
\begin{tabular}{c c c c c c c c c c c c c} \hline \hline \multirow{3}{*}{**No.**} & \multirow{3}{*}{
\begin{tabular}{c} **Station** \\ **Name** \\ **(mm)** \\ \end{tabular} } & \multicolumn{6}{c}{**Velocity with Respect to ITRF2014**} & \multicolumn{6}{c}{**Velocity with Respect to Sunda Block**} \\ \cline{3-14}  & & **EW** & **NS** & **UD** & **\(\sigma\)EW** & **\(\sigma\)NS** & **\(\sigma\)UD** & **EW** & **NS** & **UD** & **\(\sigma\)EW** & **\(\sigma\)NS** & **\(\sigma\)UD** \\  & & **(mm)** & **(mm)** & **(mm)** & **(mm)** & **(mm)** & **(mm)** & **(mm)** & **(mm)** & **(mm)** & **(mm)** & **(mm)** & **(mm)** \\ \hline
7 & CSBY & 26.55 & \(-\)10.36 & \(-\)8.00 & 0.20 & 0.19 & 0.56 & 2.43 & \(-\)0.51 & \(-\)8.00 & 0.23 & 0.21 & 0.56 \\ \hline
8 & CSEM & 24.91 & \(-\)10.02 & \(-\)5.34 & 0.18 & 0.18 & 0.57 & 0.51 & \(-\)1.15 & \(-\)5.34 & 0.22 & 0.18 & 0.57 \\ \hline
9 & CSLO & 27.96 & \(-\)7.74 & \(-\)1.21 & 0.20 & 0.17 & 0.65 & 4.01 & 1.27 & \(-\)1.21 & 0.24 & 0.18 & 0.65 \\ \hline
10 & CTBN & 25.19 & \(-\)9.77 & \(-\)2.60 & 0.20 & 0.16 & 0.52 & 0.85 & \(-\)0.24 & \(-\)2.60 & 0.23 & 0.16 & 0.52 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: _Cont._  
Figure 5: (a) Velocity vector and its associated error ellipse referenced to ITRF2014. (**b**) Velocity vector and its associated error ellipse in reference to Sunda block. The velocity visualization concerning the ITRF2014 shows a relatively uniform pattern, with a dominant displacement rate directed southeast. Meanwhile, the velocity visualization about the Sunda block exhibits a more varied pattern. The figure highlights a significant difference in the direction and magnitude of the two velocities [27]. The variation in standard deviation between velocity data referenced to the Sunda block and that referenced to the ITRF2014, as detailed in Table 1, is primarily due to the coordinate transformation applied when reducing velocities to the Sunda block reference frame. In 2023, a notable earthquake with a class magnitude of 7 occurred in the northern region of Java Island at a depth of 597 km, as documented by the USGS National Earthquake Information Center (NEIC). It can be reasonably deduced that this event had the potential for widespread impact. To assess the impact of the earthquake on the observation points, an empirical formula was employed to approximate the earthquake's radius of influence. The formula considers the magnitude of the earthquake [33]. The calculations concluded that the observation points in question were situated outside the radius of influence generated by the earthquake. We compiled the previous velocities across the Eastern Java back--arc thrust, namely from [PERSON] et al. [9] as referred to as velocity of [PERSON] (VK), from [PERSON] et al. [20] as referred to as velocity of [PERSON] (VP), and from [PERSON] et al. [18] as referred to as velocity of [PERSON] (VR), and compared it with our estimated velocities for the horizontal component, particularly as shown in Figure 4. We also summarize the detailed velocities of each study in Table 2. The visualization in Figure 6 shows that in some locations, there is an overlap of observations from various studies that show a general conformity of displacement rate direction. However, there are variations in magnitude and direction in specific locations. The eastern region shows more significant variations between studies, which may indicate the complexity of deformation in the area. \begin{table}
\begin{tabular}{c} **NS \(\pm\)\(\sigma\)** \\ **(mm)** \\ \end{tabular} \\ \hline
1 & C\&R & N/A & N/A & N/A & N/A & \(6.7\pm 0.13\) & \(-0.79\pm 0.10\) & \(-0.83\pm 0.78\) & \(-1.06\pm 0.25\) \\ \hline
2 & C\&MG & \(4.68\pm 0.57\) & \(1.13\pm 0.56\) & \(4.07\pm 0.23\) & \(0.37\pm 0.12\) & \(4.1\pm 0.03\) & \(-0.70\pm 0.03\) & \(2.22\pm 0.25\) & \(0.48\pm 0.18\) \\ \hline
3 & CMAG & \(6.76\pm 0.65\) & \(3.94\pm 1.25\) & \(5.92\pm 0.22\) & \(3.32\pm 0.11\) & \(6.2\pm 0.03\) & \(1.70\pm 0.03\) & \(4.63\pm 0.33\) & \(2.54\pm 0.20\) \\ \hline \hline \end{tabular}
\end{table}