onshore-offshore Campi Flegrei Drilling

The MTU working group became involved in potential plans for scientific drilling in 2006.

This was initiated by an ICDP workshop held in May 2006 in Naples, where land drillling plans had been discussed. As an outcome of this workshop, an ICDP drilling proposal was submitted and eventually led into the drilling project CFDDP. 

At this workshop, also ideas developed that our working group might contribute to surveying the marine sector of the caldera, which then may eventually become a target of an IODP drilling proposal .

This had then been discussed on a Magellan Workshop in Naples in November 2006 in further detail,  where marine targets for drilling were considered. At this stage we agreed to apply for funding for a site survey cruise, first through a Euromarc proposal (EU funding), which had not been considered, and then through funding sources from Italy and from the German DFG ICDP program. 

Another outcome of the workshop had been the submission of pre-proposal 671-pre to the IODP program.

After approval in 2007, a cruise with R/V Urania was planned for January 2008 to collect high-resolution multichannel seismic data . A shallow water streamer was used with single hydrophone, providing optimum resolution in very shallow water. As a source, a very small airung (2 x 0.1 L) was used to maximize the frequency range in parallel to providing several hundred meters of signal penetration.

Most importantly, we carried our the first shallow water 3D seismic data acquisition with a single streamer, comprising a line spacing of 25 meters, covering in total an area of x by y km. This was important since the internal structure of the sediment fill was likely threedimensional and would be difficult to reconstruct, if only 2D seismic lines would be available.

These site survey data have been subsequently worked up in a DFG ICDP project by Lena Steinmann (Steinmann et al., 2016, 2018), improving the understanding of the shallow caldera, its deformation history and interplay with sealevel changes and the sediment fill history and spatial depositional patterns. Thus providing a good stratigrphic reference for a drilling proposal.

While the results had been very promising to support marine drilling, the signal penetration was not good enough to reach the depth target of ICDP drilling of 2-3 km. The reason was the small airgun volume, but also the towingg configuration of <1 m below water surface, which attenuates lower frequencies.