# An Internet of Things (IoT) Application on Volcano Monitoring
## 5 Conclusions  
This article describes the development of the first reliable, robust, low-power, and low-cost scalable wireless network based on IoT that can be used for monitoring thermal anomalies in volcanic areas in real-time. Taking advantage of LoRa communication protocol, the designed network of portable thermometers (eight in total) allows continuously monitoring the temperature values on different points in the desired areas, showing the acquired values to remote users through a user-friendly web dashboard. Besides the temperature values, users can also visualize parameters related to the network operation such as RSSI, the battery levels of each thermometer, and the percentage of error in the transmission of the packages.  
The main advantage of the network presented here is its extremely low power consumption, which ensures a long battery life. A theoretical continuous operation of 2.14 years (Section 3.3 and 4.3) was estimated for each thermometer powered by a 3.7-V single battery and transmitting data every 10 min. This result assures both a proper sampling for soil temperature and long time period with no maintenance, which is vitally important in volcano monitoring, since these areas are usually remote and inaccessible.  
A low cost was achieved since the total price for the network is 384.75 \(\upmu\), with the gateway being the most expensive device (Table 7). Each thermometer had an estimated cost of 37.01 \(\upmu\) and they were designed with a suitable shape to facilitate the transport and installation. In this way, a reliable network can be quickly deployed with the proper number of thermometers and with an affordable  
Figure 18: Estimation of errors. (**a**) Percentages of total error in transmitted packets applying Equation (1); (**b**) 24-hour mean transmission error \(\pm\) standard deviation.  
price. In addition, and if it is needed, after the initial deployment, the network can be easily enlarged by adding new thermometers simply by modifying one parameter on the gateway side.  
The network was installed on 20 November 2018 in Las Canadas del Teide in Tenerife (Spain) and continues to work. The temperature values recorded (Figure 13 and Table 8) matched with previous data reported by the MultiTeide project. Thus, proper temperature monitoring is guaranteed by the developed wireless network.  
Regarding the RSSI levels (Figure 17), LoRa has showed a very good performance, confirming that it was the right choice among different transmission options. When weather conditions were not adverse, RSSI values remained higher than the sensitivity level in all thermometers. As a consequence, the network was operable the majority of the time, reaching a very low percentage error in the packages transmission: less than 2% in 24 h (Figure 18).  
Therefore, all these results confirm that the developed wireless network designed for monitoring the soil temperature in volcanic areas has accomplished the initial requirements of low power, low cost, scalable network, robust operation, and real-time communication. With minimum changes and improvements, this wireless network could be deployed in other volcanic areas to strengthen the volcano monitoring programs.  
Conceptualization, S.A., D.M., and P.T.-G.; Investigation, S.A., D.M., and P.T.-G.; Methodology, S.A., D.M., and P.T.-G.; Software, S.A. and D.M.; Supervision, D.M. and P.T.-G.; Validation, S.A., D.M., and P.T.-G.; Writing--original draft, S.A., D.M., and P.T.-G.; Writing--review and editing, S.A. and P.T.-G.  
This research was funded by the Spanish Instituto Geografico Nacional (Ministerio de Fomento). The publication was funded by CGL2014-53044-R (MULTITEIDE).  
The authors declare no conflict of interest.