Geophysical surveys

The fieldwork

Two geophysical campaigns were carried out from July to September 2022 for a total of 38 days and 6 researchers on the field. The geophysical measurements were aimed at imaging the permafrost, the active layer and the subsurface aquifers with different degrees of resolution and depth of investigation. Magnetotellurics (MT and CSAMT), Electrical Resistivity Tomographies (ERT) and Ground Penetrating Radar (GPR) geophysical methodologies were adopted in the field. Great effort went into the organization of the shipment of the equipment (14 boxes and > 450 kg) with the help of the ICETOFLUX project leader, WP1 leader and the Dirigibile Italia station leaders and managers.

Acquisition of Electrical Resistivity Tomographies (ERT)

Three sectors have been surveyed: the Bayelva basin, the Mines area and the I2F piezometers area. A Syscal (IRIS) device was used with 48 electrodes, 1-2-10 meters inter-electrode spacing, roll-along layout and various electrodes arrays. A cumulative length of 7,87 km has been surveyed along 9 deep ERTs and 9 shallow ERTs. A maximum depth of investigation of about 90-100 meters was reached.

In the area close to the I2F piezometers and the Climate Change Tower, deep and shallow surveys were carried out and the data were jointly processed with GPR data. In the area of the Bayelva river, deep ERTs investigated the spatial distribution of permafrost and sub- permafrost aquifers. Near the Ester mine, next to a spring, deep and shallow ERTs investigated the permafrost and the possible sub-permafrost aquifer.

The electromagnetic data acquisition

Georadar (GPR) lines were acquired in the area where the I2F piezometers were installed. A GSSI Sir 3000 system coupled with two antennas at 40 MHz and 400 MHz was used. The 400 MHz antenna was used for very shallow investigation targeting the interface between the active layer and the permafrost. The 40 MHz antenna was used for deeper investigation. Magnetotelluric (MT) and Controlled Source Audio MT (CSAMT) soundings were acquired in the mine areas and the Bayelva basin. The Zonge and the StrataGem systems were used.