Figure - Campi Flegrei multiparameter monitoring networks
INGV-OV researchers at work at the crater of La Solfatara in Pozzuoli for gas sampling at the “Bocca Grande” fumarole (Photo by INGV section of Naples Vesuvius Observatory).
SEISMIC MONITORING
Seismic monitoring of Campi Flegrei is carried out through the joint use of a Permanent Seismic Network and a Mobile Seismic Network, managed by the Vesuvius Observatory section of Naples. These networks make it possible to identify and classify seismic signals linked to earthquakes or other natural and artificial phenomena; in the Solfatara area the average amplitude of seismic noise is also studied. The ARF seismic array also allows to characterize the entire wave field in order to identify possible persistent and correlated seismic sources (eg volcanic tremor). The seismic events detected and localized are then archived in specific catalogues, which can also be consulted online (see Databases).
Permanent Seismic Network
The Campi Flegrei Permanent Seismic Monitoring Network has 27 land and sea installation sites. Different types of stations and sensors can be set up at each site. Overall, the network is made up of 5 analog stations with 1Hz sensors and 22 broadband digital stations. The digital terrestrial seismic stations are based on the GILDA data logger, designed and manufactured at the INGV Osservatorio Vesuviano; the marine ones are based on Guralp DM24 and Quanterra Q330 dataloggers. The seismic network sensors are joined by 5 Infracyrus infrasonic microphones, designed and produced by INGV Osservatorio Vesuviano, and an infrasonic array consisting of 4 elements. All the signals detected by the indicated sensors are transmitted in real time to the Monitoring Room of the INGV Vesuviano Observatory in Naples, where they are analyzed and processed.
Mobile Seismic Network
In the Campi Flegrei area, 17 stand-alone seismic stations are operational, equipped with broadband seismic sensors, 4 of which are also equipped with an accelerometer, an accelerometer station, a short-period station and a tiltmeter. There is also an array of 10 short period stations (ARF). This instrumentation works in local acquisition mode.
GEODETIC MONITORING
The monitoring of ground deformations in the Campi Flegrei is based on an integrated approach of continuous measurements and periodic campaigns, carried out with instrumental networks relating to various parameters, managed by the Naples Vesuvius Observatory section. The measurement and observation techniques used are GPS, tidemetry, tiltmetry, gravimetry, dilatometry, SAR interferometry and precision geometric levelling. Fixed GPS, tidal and tiltmetric networks are installed. On the other hand, precision leveling campaigns are periodically carried out on an altimetric network made up of about 370 benchmarks, and gravimetric measurement campaigns on a network made up of 38 benchmarks. 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 25 permanent GPS stations operating in the Campi Flegrei area, of which 21 located in terrestrial sites and 4 in marine sites, equipped with various types of Leica GPS receivers. 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 Vesuvius Observatory's Wi-Fi network, ADSL and UMTS/4G lines. Most of these stations are powered by the mains, and buffer battery, to ensure continuity of operation in the event of a power blackout. Other sites including the four beacons in the Gulf of Pozzuoli are powered by solar panels. The management and data transmission system is based on specific software.
Mareometric network
The Mareographic Network of Campi Flegrei consists of 4 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 in a marine environment considerably affects the accommodation facilities, therefore frequent maintenance is essential. Cornerstones of the leveling network of the Vesuvius Observatory are also located near the tide gauge stations.
Tiltmetric network
The Tiltmetric Network of Campi Flegrei consists of 10 stations, 4 of which are equipped with surface analogue sensors, mod. 702 (Applied Geomechanics Instruments), 3 equipped with analog well sensors mod. 722 (Applied Geomechanics Instruments) and 3 equipped with digital well sensors mod. Lily (Jewel Instruments). The stations transmit the recorded data files daily to the Monitoring Room of the Vesuvius Observatory.
Dilatometer network
The Campi Flegrei Dilatometric Network consists of 4 stations, equipped with Sacks-Evertson dilatometers and co-installed with stations of the Permanent Seismic Network. Of these, two stations are operational.
Gravimetric network
The Gravimetric Network of Campi Flegrei is made up of 38 relative measurement stations and 24 absolute measurement stations.
The interferometric monitoring of the deformations of the Campi Flegrei exploits the Synthetic Aperture Radar (SAR) data acquired by the main satellite constellations currently in operation: TerraSAR-X (TSX) of the German Space Agency, COSMO-SkyMed (CSK) of the Italian Space Agency ( ASI) and Sentinel-1 (S1) of the European Copernicus programme, managed by the European Space Agency (ESA). The Vesuvius Observatory Naples section carries out the analysis of TerraSAR-X (TSX) data. The data acquired from the other constellations are used by other research institutes.
GEOCHEMICAL MONITORING
The geochemical monitoring activities of the Campi Flegrei area consist in the continuous acquisition of the measurement of the flow of CO2 from the soil, the temperature of the fumaroles and the soil, the thermal gradient of the soil and the main environmental parameters which have an effect on the process of degassing of the Solfatara di Pozzuoli crater area and the Pisciarelli area, as well as in the collection and chemical and isotopic analysis of gas samples during periodic measurement campaigns. These activities are carried out by the Vesuvius Observatory Section of Naples. The Roma1 Section continuously acquires the soil temperatures along vertical profiles through stations installed in the Solfatara and Pisciarelli areas. The study of the chemical-physical variations of the fluids in these areas provides important information on the circulation of fluids and on the magmatic dynamics taking place in the volcanic system.
Geochemical networks
The Campi Flegrei Geochemical Network of the Vesuvius Observatory consists of four automatic multi-parameter stations in continuous recording: FLXOV1, GTS1 and FLXOV5 installed in the Solfatara area and FLXOV3 in the Pisciarelli area. A new GEMMA type station in the Pisciarelli area was also installed and is currently being tested, which will replace the FLXOV3 station. The stations send the data collected in real time to the Monitoring Center of the Vesuvius Observatory with wi-fi connection. On pre-established fixed points (about 60 points in the Solfatara crater area and 28 points in the Pisciarelli area) CO2 flux and soil temperature measurements are carried out. Periodic samplings are also carried out of the gases emitted by the fumaroles present in the Solfatara and Pisciarelli craters.
The continuous geochemical network of soil temperatures in the Rome 1 section consists of two stations (PSC and SLF) for measuring temperatures on vertical profiles in the soil (from 10 to 70 cm).
VOLCANOLOGICAL 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 as its main objective the identification of 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
The TIRNet (Thermal InfraRed Network) network for continuous long-term volcanic surveillance of the Campi Flegrei through the acquisition of thermal infrared images is currently made up of 5 permanent stations, two of which are located inside the Solfatara crater (SF1, SF2 ), one in Pisciarelli (PS1), the fourth (OBN) is located at the base of the SE slope of the lava dome of Mount Olibano and the fifth (IR-SOB) is located on the south-eastern edge of the Solfatara crater. These stations are equipped with FLIR thermal imaging cameras. The thermal images are transmitted via wi-fi and UMTS connection and 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 16 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.
Deepening