## 3 Results
### Strain Tensor Analysis and Spatial Characterization of Deformation  
Each method serves a specific interpretive purpose. Density maps highlight where most of the coordinate differences are concentrated, offering insight into central tendencies and outlier structures. Scatter plots help reveal the dispersion and clustering behavior, while polar histograms provide information on azimuthal directionality that may be related to network geometry, processing strategy, or localized effects. A total of six primary deformation parameters were derived from the strain tensor for each triangular element. These include the principal strain rates (\(\epsilon_{1}\), \(\epsilon_{2}\)), principal axis orientation (\(\theta_{\rm p}\)), maximum shear strain rate (\(\gamma_{\rm max}\)), its orientation (\(\theta\_{\rm ymax}\)), and areal strain rate (\(\Delta\)). These values serve as key indicators for quantifying local contraction, extension, rotation, and shear deformation within each triangular cell. Table 1 summarizes the primary deformation parameters estimated for 32 triangular elements based on strain tensor analysis. For each triangle, six key indicators were computed: the first and second principal strain rates (\(\epsilon_{1}\) and \(\epsilon_{2}\)), the orientation of the principal axis (\(\theta_{\rm p}\)), the maximum shear strain rate (\(\gamma_{\rm max}\)), the orientation of maximum shear (\(\theta\_{\rm ymax}\)), and the areal strain rate (\(\Delta\)). These parameters provide a quantitative assessment  
This triangle shows a very high principal strain value and dilatation, suggesting a region of concentrated tectonic deformation. The shear strain is also significantly elevated, which could be indicative of active faulting along or near the Yangsan Fault. * Triangle 10:
* Maximum Shear Strain: 2.984 \(\upmu\)strain/yr
* Shear Stress Direction: 18.84\({}^{\circ}\)
* Principal Strain: 2.367 \(\upmu\)strain/yr and \(-\)0.617 \(\upmu\)strain/yr
* Principal Axis Orientation: 68.30\({}^{\circ}\)
* Dilatation: 1.750 \(\upmu\)strain/yr  
Triangle 10 also demonstrates high shear strain, highlighting a region with intense deformation, likely linked to active fault movement along the fault system. * Triangle 11:
* Maximum Shear Strain: 1.105 \(\upmu\)strain/yr
* Shear Stress Direction: 21.24\({}^{\circ}\)
* Principal Strain: \(-\)2.241 \(\upmu\)strain/yr and \(-\)3.346 \(\upmu\)strain/yr
* Principal Axis Orientation: 72.30\({}^{\circ}\)
* Dilatation: \(-\)5.588 \(\upmu\)strain/yr  
This triangle has negative strain values, which suggest contraction or compression in the region. The high dilatation rate of \(-\)5.588 \(\upmu\)strain/yr could reflect a potential region of significant fault activity or localized compressive stress buildup. * Triangle 45:
* Maximum Shear Strain: 1.442 \(\upmu\)strain/yr
* Shear Stress Direction: 89.25\({}^{\circ}\)
* Principal Strain: 1.906 \(\upmu\)strain/yr and 0.464 \(\upmu\)strain/yr
* Principal Axis Orientation: 125.89\({}^{\circ}\)
* Dilatation: 2.370 \(\upmu\)strain/yr  
This triangle shows a balanced strain pattern, with noticeable contraction and extension. The high dilatation suggests that this region might be experiencing localized extension, which could indicate evolving fault dynamics in this section. These high-strain values in specific triangles point to areas with notable deformation, likely indicative of ongoing tectonic processes or active faulting. Notably, triangles with larger shear strain values, such as Triangle 6 and Triangle 10, highlight areas with heightened seismic potential. These zones are critical for further monitoring, as they may represent concentrated stress accumulation or potential rupture sites along the Yangsan Fault or its adjacent segments. The regions identified through this analysis are critical to understanding the active tectonic processes in southeastern Korea. High-resolution monitoring in these areas is recommended for more detailed seismic hazard assessment.