The BENTO Box: Development and field-testing of a new satellite-linked data collection system for multiparameter volcano monitoring

Abstract:

Predicting volcanic activity requires continuous monitoring for signals of magmatic unrest in harsh, often remote environments. BENTO is a next-generation monitoring system, currently in prototype testing, that is highly portable, low-cost, rapidly deployable, and entirely autonomous. Such a system could be used to provide critical monitoring and data collection capabilities during rapid-onset eruptions, or to provide a crude baseline monitor at large numbers of remote volcanoes to 'flag' the onset of unrest so that costlier resources such as specialized instrumentation can be deployed in the appropriate place at the appropriate time. The BENTO 1 (low-rate data) prototype currently comprises off-the-shelf volcanic gas sensors (SO₂, CO₂, Fl, Cl, and Br), a weather station (temperature, wind speed, wind direction, rainfall, humidity, pressure), and telemetry via Iridium modem. In baseline mode, BENTO 1 takes a measurement from all of its sensors every two hours and automatically sends the measurements through Iridium to a server that posts them to a dedicated and customizable web page. The measurement interval and other sensor parameters (pumping time, sensor constants) can be adjusted directly or remotely (through the Iridium network) as needed. Currently, BENTO 1 is deployed at Mt. Etna, Italy; Telica Volcano, Nicaragua, Hengill Volcano, Iceland; and Hekla Volcano, Iceland. The BENTO 2 (high-rate) system is motivated by a need to avoid having to telemeter raw seismic data, which at 20-100 Hz/channel is far too voluminous for cost- and power-effective transmission through satellite networks such as Iridium. Our solution is to regularly transmit only state-of-health information and descriptions of the seismic data (e.g., 'triggered' seismic event rates and amplitudes), rather than the data itself. The latter can be accomplished through on-board data analysis and reduction at the installation site. Currently, it is possible to request specific time segments of raw seismic data from a BENTO 2 through the Iridium network, based on regularly transmitted lists of automated trigger times, allowing verification of any apparent changes in seismic event rate. BENTO 2 prototypes have recently been deployed at Telica Volcano, Nicaragua; and Hekla Volcano, Iceland.