The drillings of the ICDP-DIVE project located in the Central part of the Ivrea-Verbano Zone at the Linea Cadorna in Migiandone near Ornavasso were accompanied by On-Line Gas Monitoring. During the drilling of both boreholes 5071_1_A (IGSN ICDP5071EH10001) and 5071_1_B (IGSN ICDP5071EH30001) O2, N2, 40Ar, 38Ar, 36Ar, CO2, CH4, H2, He and 222Rn were measured. The dataset contain for each species its concentration over time and depth. Gases were continuously recovered by degassing the drilling mud and quantified using two quadrupole mass spectrometers (QMS): an Omnistar GSD 300 (Pfeiffer Vacuum®, Germany) and a miniRUEDI (Gasometrix®, Switzerland) and an AlphaGUARD radon monitor (Bertin Technologies®, France). Baselines were corrected using the asymmetric least squares smoothing method from Eilers and Boelens (2005) resulting in an uncertainty not exceeding 3% for all the concentrations. All data provided are lag-time (and lag-depth) corrected with an error of less than 1 m.
For the determination of the exact location and drilling geometry of the ICDP expedition 5071 DIVE (Drilling the Ivrea-Verbano zonE) phase 1 boreholes, we have carried out a series of active seismic experiments to image the subsurface at high resolution (Greenwood et al., 2024). The two drilling sites of DIVE phase 1 are located in the Ossola valley (Figure 1) in the Central part of the Ivrea-Verbano zone, one in Megolo di Mezzo (5071_1_A: IGSN ICDP5071EH10001, Münthener, 2024a) and the other near Ornavasso (5071_1_B: IGSN ICDP5071EH30001, Münthener, 2024a). A total of 4 seismic reflection surveys, one in Megolo, two in Ornavasso (Ornavasso primary and Or-navasso secondary), and a transect crossing from Premosello-Chiovenda south towards Megolo, make up the MicrO-SEIZE (MOS) data base.
The MOS surveys were conducted over a period of 12 days mid to late June 2019, utilizing a 26,000 lb (12,247 kg) EnviroVibe2™ vibrator source. Survey planning utilised existing roads, pathways, and open grass fields to cover as much area as possible around the borehole sites, to reduce the envi-ronmental impact on cultivation, and to ease operation logistics. A full description of the data can be found in Greenwood et al. (2024) and the data description file accessible via the data download link.