# An Internet of Things (IoT) Application on Volcano Monitoring
## 4 Results and Discussion
### Data Records  
The sampling frequency is 10 min to ensure a proper recording of soil temperature, although different time intervals can be programmed via Secure Shell (SSH) and modifying the corresponding file. The temperature wireless network has been operating for over three months, allowing the verification of the robustness of both the network operation and each individual device, and the quality of temperature recordings. Up to the date of sending this article, it is still continuing to work. Table 8 summarizes the data collected by the network since it was installed. Under normal conditions, the operation of the network is quite stable, and the temperature measurements of each thermometer match the expected values according to MultiTeide campaigns (Table 8, Figures 12 and 13). Variations in the temperature values are associated with changes in meteorological conditions and/or volcanic activity [92]. However, during this period of time, there were some issues that affected the normal function of the network. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & **Samples** & & **T (°C)** & **RSSI (dBm)** & **BAT (V)** \\ \hline \multirow{3}{*}{**T1**} & \multirow{3}{*}{14522} & MIN & 31.87 & –101 & 3.27 \\ \cline{3-6}  & & MED & 36.95 & –92 & 3.55 \\ \cline{3-6}  & & MAX & 40.18 & –89 & 3.58 \\ \hline \multirow{3}{*}{T2} & \multirow{3}{*}{13005} & MIN & 61.91 & –107 & 2.57 \\ \cline{3-6}  & & MED & 82.82 & –95 & 3.56 \\ \cline{3-6}  & & MAX & 83.88 & –92 & 3.64 \\ \hline \multirow{3}{*}{**T3**} & \multirow{3}{*}{14480} & MIN & 50.52 & –123 & 3.54 \\ \cline{3-6}  & & MED & 63.17 & –89 & 3.57 \\ \cline{3-6}  & & MAX & 68.31 & –84 & 3.59 \\ \hline \multirow{3}{*}{T4} & \multirow{3}{*}{14445} & MIN & 13.04 & –102 & 3.98 \\ \cline{3-6}  & & MED & 15.95 & –92 & 4.06 \\ \cline{3-6}  & & MAX & 18.00 & –89 & 4.10 \\ \hline \multirow{3}{*}{T5} & \multirow{3}{*}{14466} & MIN & 58.89 & –114 & 3.61 \\ \cline{3-6}  & & MED & 68.70 & –101 & 3.87 \\ \cline{3-6}  & & MAX & 81.09 & –95 & 4.10 \\ \hline \multirow{3}{*}{T6} & \multirow{3}{*}{14445} & MIN & 28.68 & –115 & 3.40 \\ \cline{3-6}  & & MED & 41.08 & –103 & 3.47 \\ \cline{3-6}  & & MAX & 77.77 & –99 & 3.59 \\ \hline \multirow{3}{*}{**T7**} & \multirow{3}{*}{14551} & MIN & 14.75 & –116 & 3.92 \\ \cline{3-6}  & & MED & 16.90 & –103 & 3.99 \\ \cline{3-6}  & & MAX & 18.75 & –94 & 4.08 \\ \hline \multirow{3}{*}{T8} & \multirow{3}{*}{9565} & MIN & 79.29 & –104 & 3.43 \\ \cline{3-6}  & & MED & 82.43 & –90 & 3.56 \\ \cline{3-6}  & & MAX & 83.41 & –86 & 4.10 \\ \hline \hline \end{tabular}
\end{table} 
Table 8: Descriptive statistics of the data recorded by the network. After the network deployment, there were some periods when the weather conditions in Las Canadas del Teide worsened notably, especially in the Teide crater, where rains and snowfalls took place and a layer of thick clouds was permanently established. Therefore, the network robustness was able to be tested under adverse weather conditions. Due to the layer of snow that covered both the repeater and the thermometers, the RSSI of all these elements decreased. In addition, the layer of clouds that settled frequently on the summit part of Teide volcano interrupted the gateway-repeater link. This was mainly because the gateway antenna has low gain, so the gateway-repeater link was the weaker one when extreme adverse weather conditions took place (therefore, one possible improvement would be to use a higher gain antenna). Consequently, temperature measurements were not acquired (grey dashed rectangles in Figures 13 and 14) during these periods. Once the weather conditions became more favorable, the snow melted and the network returned to operation again (Figures 13 and 14). When a transmission error occurred, no temperature registration value was available for that thermometer in that sample, which translated into a gap (Figure 13). Figure 15 and Table 8 display the battery records of each thermometer.