On 10 October 2011, a submarine volcanic eruption started 2 km south from El Hierro Island (Spain). Since July 2011 a dense multiparametric monitoring network was deployed all over the island by Instituto Geográfico Nacional (IGN). By the time the eruption started, almost 10000 earthquakes had been located and the deformation analyses showed a maximum deformation of more than 5 cm. Earthquake migration from the north to the south of the island and acceleration of seismicity are in good correlation with changes in the deformation pattern as well as with some anomalies in geochemical and geomagnetic parameters. An earthquake of local magnitude 4.3 at 12 km depth (8 October 2011) and shallower seismicity a day after, preceded the onset of the eruption. This is the first time that a volcanic eruption is fully monitored in the Canary Islands. Data recorded during this unrest episode at El Hierro will contribute to understand reawakening of volcanic activity in this region and others of similar characteristics.

In the last few years, there has been a huge interest in the Internet of Things (hereinafter IoT) field. Among the large number of IoT technologies, the low-power wide-area network (hereinafter LPWAN) has emerged providing low power, low data-rate communication over long distances, enabling battery-operated devices to operate for long time periods. This paper introduces an application of long-range (hereinafter LoRa) technology, one of the most popular LPWANs, to volcanic surveillance. The first low-power and low-cost wireless network based on LoRa to monitor the soil temperature in thermal anomaly zones in volcanic areas has been developed. A total of eight thermometers (end devices) have been deployed on a Teide volcano in Tenerife (Canary Islands). In addition, a repeater device was developed to extend the network range when the gateway did not have a line of sight connection with the thermometers. Combining LoRa communication capabilities with microchip microcontrollers (end devices and repeater) and a Raspberry Pi board (gateway), three main milestones have been achieved: (i) extreme low-power consumption, (ii) real-time and proper temperature acquisition, and (iii) a reliable network operation. The first results are shown. These results provide enough quality for a proper volcanic surveillance.

This paper describes the development of a low-cost multiparameter acquisition system for volcanic monitoring that is applicable to gravimetry and geodesy, as well as to the visual monitoring of volcanic activity. The acquisition system was developed using a System on a Chip (SoC) Broadcom BCM2835 Linux operating system (based on DebianTM) that allows for the construction of a complete monitoring system offering multiple possibilities for storage, data-processing, configuration, and the real-time monitoring of volcanic activity. This multiparametric acquisition system was developed with a software environment, as well as with different hardware modules designed for each parameter to be monitored. The device presented here has been used and validated under different scenarios for monitoring ocean tides, ground deformation, and gravity, as well as for monitoring with images the island of Tenerife and ground deformation on the island of El Hierro.

In this paper we present low-power seismic acquisition equipment for long-range telemetry, developed as a compact system for easy transportation. This acquisition system has been developed to detect the seismic activity of volcanoes, and represents the achievement of joint work from different scientific and technological disciplines such as geophysics, electronics, communications, mechanics, and information technology. The paper includes the laboratory validation results by means of automated measuring systems and calibration procedures, and the final validation results of different measurement campaigns on the El Hierro and Tenerife islands (Canary Islands). The seismic acquisition equipment includes an on board signal processing system developed to reduce the size of seismic data transmitted and to increase the autonomy of the equipment. Moreover, the seismic acquisition equipment has been designed based on a low cost electromagnetic sensor, which has been conditioned to achieve our goals. In a volcanic seismic survey, a series of seismic acquisition systems are placed near the area under study, where they record the natural seismic activity of volcanoes.Peer ReviewedPostprint (author's final draft