# Exploring the Dynamics of Global Plate Motion Based on the Granger Causality Test
## 4 Discussion
However, some people hold opposing views about this process [35; 62; 63]; they think the subduction force may be overestimated and the force is similar in magnitude to the ridge-push force. The results obtained from the perspective of statistical physics in the current research are generally in agreement with previous studies, and further point out the plates where this conclusion applies [32; 33; 34]. However, the conclusion does not apply to certain plates, such as the SO and IN plates, which requires further study. Mechanically, the faulting events occurring in mid-ocean ridges usually represent normal faulting due to separating plates, causing less differential stress tensional regimes. In contrast, in collision zones and subduction zones, high stress is generated due to the compressive regime, which usually causes thrust faulting. In addition to revealing the relationship between a subduction zone and a mid-ocean ridge, this research also found a causality relationship between continental plate boundaries. Boundaries of the Eurasian plate also have causality relationships. Unidirectional Granger causality running from PS-EU to AF-EU and from PS-EU to IN-EU can be distinguished (yellow marks in Figure 4). At the same time, there is a causality relationship between the two boundaries of the Philippine sea plate running from PS-EU to PA-PS. This direction is also opposite to the global plate motion field. In other words, it is consistent with the previous conclusions that the slab pull force provides the main driving force for plate motion in the Eurasian plate and the Philippine sea plate. Due to the great destructive power of earthquakes and large risks to personal safety, earthquake prediction is a very important job. Even though it has motivated an international effort and achieved certain results, our ability to forecast earthquakes remains weak. In the present paper, the causality relationship between energy release and earthquake events at plate boundaries provides another point of view to forecasting earthquakes. An earthquake can Granger cause an earthquake at another plate boundary after a certain period of time. In addition, the period, the optimal lag length, and the rupture size were estimated with the Granger causality test. Here, we do not directly analyze the geological characteristics of a region, such as fault geometry, geodetic strain rates, past earthquakes, and a slip rates, to forecast earthquakes. Instead, we consider the transfer relationship of energy between seismic fault zones. Although the validity of the conclusions of the study remains to be verified, it is a meaningful attempt to forecast earthquakes from the perspective of statistical physics. By analyzing the earthquake catalog dataset, the paper studied the relationship and interaction between energy release and plate boundaries from the perspective of statistical physics. The analysis yields various results that can provide a new way to understand the geodynamic mechanism and seismic energy transfer relationship, and even earthquake prediction. However, there are certain limitations in this study that need to be considered in the future. (1) The use of statistical physics methods requires high-quality data. Although the completeness of the earthquake catalog has been evaluated using the Gutenberg-Richter law (states that earthquake magnitudes are distributed exponentially [51] as \(Log\ 10N(\text{m})=a-bm\), where \(N(\text{m})\) is the number of earthquakes with magnitude larger or equal to m, \(b\) is a scaling parameter, and \(a\) is a constant), the study has been limited to some extent due to the short time range of earthquake record data. Therefore, it is still necessary to build earthquake datasets with longer observation times and higher precision. (2) Energy release at subduction zones and collision zones Granger causes energy release at mid-ocean ridges. Therefore, this method may provide a reference for earthquake prediction at mid-ocean ridges.