Figure - Multi-parameter monitoring networks of the Somma-Vesuvius
Hypocentral locations to Vesuvius over the course of 12 months: from November 2017 to November 2018. The size of the symbols is proportional to the magnitude, as indicated in the lower right box (modified from Surveillance Bulletin INGV/OV – VESUVIO NOVEMBER 2018).
SEISMIC MONITORING
The monitoring of the seismic activity of Vesuvius is carried out through the joint use of a Permanent Seismic Network and a Mobile Seismic Network, managed by the INGV section of Naples Vesuvius Observatory (OV). These networks make it possible to identify and classify seismic signals linked to earthquakes or other natural and artificial phenomena. The seismic events detected and localized are then archived in specific catalogues, which can also be consulted online (see Databases).
Permanent Seismic Network
The Vesuvius Permanent Seismic Monitoring Network has 19 installation sites. Different types of stations and sensors can be set up at each site. Overall, the network consists of 7 analog stations with 1Hz sensors and 13 broadband digital stations based on the GILDA data acquisition system, designed and manufactured at the INGV Vesuviano Observatory. At the OVO site, located near the historic headquarters of the Vesuvius Observatory, there are two different seismic stations, one of which is in a well. The seismic network sensors are joined by 6 Infracyrus infrasonic microphones, designed and produced by INGV-OV, a broadband microphone and an accelerometer. All the signals detected by the indicated sensors are transmitted in real time to the INGV-OV Monitoring Room in Naples, where they are analyzed and processed.
Mobile Seismic Network
In the Vesuvius area, 7 stand-alone seismic stations are operational, equipped with broadband seismic sensors, an accelerometer and a tiltmeter. This instrumentation works in local acquisition mode.
GEODETIC MONITORING
The monitoring of Vesuvius soil deformations is based on an integrated approach of continuous measurements and periodic campaigns, carried out with instrumental networks managed by the OV, which measure various parameters. The measurement techniques used are GPS, tidemetry, tiltmetry – equipped with fixed networks – as well as gravimetry and precision geometric levelling. For the latter, the measurement campaigns are periodically carried out on networks made up of 37 cornerstones for gravimetry and about 350 cornerstones for precision levelling. The analysis of the acquired data is carried out separately for the signals of the various networks and subsequently integrated into a single database.
GPS network
There are 11 permanent GPS stations operating in the Vesuvius area, with GPS receivers of the GRX1200PRO series. The collected data is transmitted to the operational headquarters of the INGV Osservatorio Vesuviano with various technologies, according to the logistics of the site. The transmission systems currently in use use the OV Wi-Fi network, ADSL and GSM lines. Three sites are equipped with 100W photovoltaic panels and powered by solar energy. For the other sites, connected to the electricity grid, buffer batteries are available to extend their operation in the event of a blackout. The management and data transmission system is based on ad hoc software and on Leica Geosystem Spider software.
Mareometric network
The Vesuvius Mareographic Network consists of 5 stations. The monitoring of the tidal level is carried out by means of float sensors (in still-pipe) connected to a digital encoder. The signals, sampled every minute, are acquired and transmitted via GSM modem. The power supply is of the solar type with photovoltaic panels. The stations are installed in metal cabins and fiberglass containers. The location of the sensors in the marine environment greatly affects the accommodation facilities and therefore frequent maintenance is essential. Cornerstones of the OV leveling network are also located near these stations.
Tiltmetric network
The Vesuvius Tiltmetric Network consists of 7 stations, 3 of which are equipped with analog surface sensors, mod. 702 (Applied Geomechanics Instruments) and 4 equipped with digital well sensors, mod. Lily (Jewel Instrument). Six stations transmit data files daily to the Monitoring Room of the Vesuvius Observatory. For the Trecase station, destroyed by the fires of July 2017, the local acquisition and periodic download of data is provided.
GEOCHEMICAL MONITORING
The geochemical monitoring activities at Vesuvius consist in the continuous acquisition of data on the flow of CO2 from the ground, the temperature and the temperature gradient of the ground in the fumarolic fields present both in the crater rim area and on the crater floor; in carrying out periodic campaigns to measure the CO2 flux and the soil temperature at a depth of 10 cm, on a mesh of 40 fixed points located in the crater floor area; in sampling and chemical and isotopic analysis of gas samples from crater floor and crater rim fumaroles. Furthermore, periodic measurements of the CO2 flux and of the soil temperature are carried out at fixed points in the crater area. These activities are carried out by the Vesuvius Observatory. The INGV Section of Palermo carries out periodic sampling of the water from some wells and springs, mostly on the south-western flank of the volcano, and continuous measurements of the temperature of the aquifer.
Geochemical networks
The Vesuvius Geochemical Network of the Vesuvius Observatory consists of two automatic multi-parameter stations in continuous recording: FLXOV6, installed in the crater edge area (SW sector) and FLXOV7 installed in the crater floor area, both for the continuous measurement of the CO2 flow from the ground, the temperature of the main fumarole and the temperature gradient of the ground. The stations send the data collected in real time to the Monitoring Center of the Vesuvius Observatory with wi-fi connection. At pre-established fixed points, discrete measurements of the CO2 flow and temperature and gas sampling are carried out.
For the geochemical monitoring of the waters, the Palermo Section makes use of a network consisting of two stations, relating to the measurement of the temperature of the underground aquifers, installed in a well and in a spring, with local data recording. To these are added another 5 sites where periodic sampling campaigns of the aquifer are carried out, for a total of 7 sites.
VOLCANIC MONITORING
Volcanological monitoring activities are carried out by the Naples Vesuvius Observatory Section with a Permanent Network of Thermal Cameras and with measurement campaigns carried out with a Mobile Thermal Camera and Thermocouple. Monitoring with thermal cameras has the main objective of identifying any variations in time and space of the temperature values measured on the ground in significant points of the crater area.
Permanent Network Image Thermal Monitoring
On the edge of the crater of Vesuvius there is a permanent station for the acquisition of thermal infrared images. This station is equipped with a FLIR thermal imaging camera and frames the internal south-western slope of the Vesuvius crater. The thermal images, transmitted via wi-fi connection, are available in the Monitoring Room of the Vesuvius Observatory.
Discreet Monitoring with Mobile Thermal Cameras (TTM) and Thermocouple
The surveys are carried out on two fixed points on a monthly basis, at night and in any case in conditions of no solar radiation, using a high resolution and sensitivity FLIR SC640 portable thermal imaging camera. The thermocouple used is type K. The measurements obtained with the thermocamera are compared, when possible, with those performed with a rigid thermocouple.