the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Fluid Conduits and Shallow Reservoir Structure Defined by Geoelectrical Tomography at the Nirano Salse (Italy)
Gerardo Romano
Marco Antonellini
Domenico Patella
Agata Siniscalchi
Andrea Tallarico
Simona Tripaldi
Antonello Piombo
Abstract. Mud volcanoes are fluid escape structures allowing for surface venting of hydrocarbons (mostly gas but also liquid condensates and oils) and water/sediment slurries. For a better understanding of Mud volcanoes dynamics, the characterization of the fluid dynamics within mud volcanoes conduits, the presence, extent, and depth of the fluid reservoirs as well as the connection among aquifers, conduits, and mud reservoirs play a key role. To this aim, we performed a geoelectrical survey in the Regional Nature Reserve of the Nirano Salse, located at the edge of the Northern Apennines (Fiorano Modenese, Italy), an area characterized by several active mud fluid vents. This study, for the first time, images the resistivity structure of the subsoil along two perpendicular cross sections down to a depth of 250 m. The electrical models show a clear difference between the Northern and Southern sectors of the area, where the last hosts the main discontinuities. Shallow reservoirs, where fluids muds accumulate are spatially associate to the main fault/fracture controlling the migration routes associated with surface venting and converge at depth towards a common clayey horizon. There is no evidence of a shallow mud caldera below the Nirano area. These findings represent a step forward in the comprehension of the Nirano Salse plumbing system and in pinpointing local site hazards, which promotes safer tourist access to the area along restricted routes.
Gerardo Romano et al.
Status: open (extended)
-
RC1: 'Comment on egusphere-2023-38', Anonymous Referee #1, 08 Mar 2023
reply
General comments
This manuscript describes the application of 2D electrical resistivity surveys for the deeper characterization of an area where several active mud volcanoes are presents (Nirano Salse, Northern Apennines, Italy). The main goal is to individuate fluid reservoirs as well as their connection among aquifers, conduits, and mud reservoirs. This information is fundamental for the understanding of Mud volcanoes dynamics and the assessment of local site hazards for a safer tourist access to the area. Finally, the methodology is potentially applicable to other mud volcanoes areas around the world.
In general, the paper is clear and well written, however some paragraphs could be improved.
Specific comments
- Section 2 Geological introduction to the area and section 3.1 Previous geophysical data.
I suggest the authors add a figure summarizing geological information and previous geophysical investigations.
- Section 3.2.1.1 Dipole-Dipole data inversion
Line 233: 40% of reciprocal error is a quite high threshold. Please, explain how the authors Please, explain how the authors established as effective this threshold and why they didn’t consider lower values of reciprocal error for data filtering.
Line 237: respect the reciprocal error filtering, how many data were filtered using the stacking error method? what is the percentage of stacking error considered?
- Section 3.2.1.2 Wenner-Schlumberger and Pole-Dipole data inversion
How many data were filtered for WS and PD surveys using the stacking error method?
- Section 4.1 SW-NE ERT1 section
Lines 399-400: the “common deep conductor” needs to be better highlighted in figure 9.
Technical corrections
- Line 106: “deep electric geoelectric tomography surveys”. There is an unnecessary repetition.
- The text in figure 1 is too small.
- Line 259: change “resistivity” with “Resistivity”.
- Figure 5: check the order of the panels as described in the caption.
- Figure 8: the quality of the image must be improved.
- Line 414: change “Ne-SW” with “NE-SW”.
Citation: https://doi.org/10.5194/egusphere-2023-38-RC1 -
AC1: 'Reply on RC1', Agata Siniscalchi, 21 Mar 2023
reply
We thank the Referee for her/his useful comments.
As regards the “specific comments”:
- We modified the figure 1 in order to include geological information and the location of the previous geophysical studies performed in Nirano area.
- We modified the main text to better explaining the dataset filtering procedure. In detail, we explained that the 40% threshold of reciprocal error was used only preliminarily. An additional dataset reduction, based on outliers discarding in the apparent resistivity pseudosection, was carried out. The final mean reciprocal error percentage was 6%.
- We added the required information on the WS and P-DD data inversion
- We modified figure 9 in order to better highlight the “common deep conductor”.
We also performed all the suggested technical corrections.
Citation: https://doi.org/10.5194/egusphere-2023-38-AC1
-
AC1: 'Reply on RC1', Agata Siniscalchi, 21 Mar 2023
reply
Gerardo Romano et al.
Gerardo Romano et al.
Viewed
HTML | XML | Total | BibTeX | EndNote | |
---|---|---|---|---|---|
174 | 39 | 11 | 224 | 2 | 2 |
- HTML: 174
- PDF: 39
- XML: 11
- Total: 224
- BibTeX: 2
- EndNote: 2
Viewed (geographical distribution)
Country | # | Views | % |
---|
Total: | 0 |
HTML: | 0 |
PDF: | 0 |
XML: | 0 |
- 1