## 5 Discussion and Conclusions  
Based on the seismic stress triggering theory and elastic dislocation theory, we compute the coulomb stress changes on two inferred rupture planes according to the focal mechanism solutions of each \(M\geq 6\) aftershock. The computation results show that the vast majority of the \(M\geq 6\) aftershocks occurred within areas of coulomb stress increases (>0.1 bar). Based on the focal mechanism solutions from USGS, we also computed the coulomb stress changes in the focal source of each aftershock. These possible coulomb stress changes are greater than the threshold of coulomb stress triggering (0.1 bar). As shown in Table 1, the majority of the coulomb stress calculation results is positive, except for the result for the \(M\) 6.9 aftershock on the nodal plane: 183,76,85. For the other five \(M\geq 6\) aftershocks, the coulomb stress changes on both fault planes increased at varying degrees. Among them, the maximum increase reached 7.564 bar and the minimum increase was 0.159 bar. Thus, the \(M\geq 6\) aftershock distribution is well explained by the seismic coulomb stress changes caused by the Ecuador \(M\) 7.8 mainshock. In this study, the coulomb stress triggering among the Ecuador \(M\) 7.8 mainshock and subsequent \(M\geq 6\) aftershocks was investigated. It should be noted that there is much randomness and uncertainty as regards the time and location of an earthquake. Data and model uncertainties are still the biggest obstacle in determining quantitatively whether coulomb stress triggered the subsequent aftershocks. These uncertainties include the finite fault model, earthquake distribution, focal depth, and focal mechanism solutions. The nodal plane uncertainties add random noise to the stress change estimates \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Date**} & \multirow{2}{*}{**Aftershock**} & **Latitude** & **Depth** & **Strike Dip** & \multicolumn{2}{c}{**Stress Change (Bar)**} \\  & & **Longitude** & **(Gm)** & **Rake (\({}^{\circ}\))** & **Shear** & **Normal** & **Coulomb** \\ \hline
20 April & \(M\) 6.2 & \(0.639\) & \(11.5\) & \(181,79,82\) & \(6.458\) & \(2.766\) & \(7.564\) \\  & & \(80.210\) & \(38,13,127\) & \(6.477\) & \(-0.260\) & \(6.373\) \\ \hline
20 April & \(M\) 6.0 & \(0.708\) & \(11.0\) & \(199,79,97\) & \(3.006\) & \(-2.104\) & \(2.164\) \\  & & \(80.035\) & \(346,13,58\) & \(3.015\) & \(0.119\) & \(3.062\) \\ \hline
22 April & \(M\) 6.0 & \(0.292\) & \(11.5\) & \(187,74,86\) & \(2.022\) & \(3.688\) & \(3.497\) \\  & & \(80.504\) & \(11.5\) & \(22,16,104\) & \(2.011\) & \(-0.485\) & \(1.847\) \\ \hline
18 May & \(M\) 6.7 & \(0.426\) & \(16.0\) & \(168,77,79\) & \(-2.249\) & \(13.871\) & \(3.299\) \\  & & \(79.790\) & \(29,16,130\) & \(-2.175\) & \(5.837\) & \(0.159\) \\ \hline
18 May & \(M\) 6.9 & \(0.495\) & \(35.5\) & \(183,76,85\) & \(-1.711\) & \(-1.149\) & \(-2.170\) \\  & & \(79.616\) & \(23,15,110\) & \(-1.739\) & \(6.251\) & \(0.762\) \\ \hline
11 July & \(M\) 6.3 & \(0.581\) & \(25.5\) & \(178,71,79\) & \(-1.465\) & \(1.030\) & \(1.053\) \\  & & \(79.638\) & \(25.5\) & \(29,22,119\) & \(-1.449\) & \(-1.123\) & \(1.898\) \\ \hline \hline \end{tabular}
\end{table} 
Table 1: The basic parameters of the \(M\geq 6\) aftershocks and stress change calculation results. and systematically reduce a potentially large coulomb index [11]. It is difficult to perfectly explain the complex geological phenomenon by only the coulomb stress triggering hypothesis. The original aim of this study is to provide a more reliable seismic hazard assessment in the Ecuador earthquake zone by considering the interaction of the earthquake sequences. In this paper, it should be noted that we only adopted one finite fault model inverted from GSN broadband waveforms to compute the coulomb stress changes. However, the source model has much inherent uncertainty due to input data errors, model assumptions, and model estimation procedures [40].