Mud flow dynamics at gas seeps - Nirano Salse, Italy -

The Nirano Salse, known since the Roman Times, are one of the most beautiful and scenic mud volcanoes areas of Italy
with thousands of visitors every year. In this work, we apply novel (for the context) hydrogeological techniques to characterize
mud levels in the Salse by means of GPS-RTK positioning and continuous level logging within mud conduits. This
is important to quantify the gas–liquid ratio in the conduits and evaluate the potential for dangerous abrupt mud eruptions.
The results presented suggest that different mud levels in mud volcanoes clusters are due to the different gas–liquid ratio in
the conduits and not necessarily exclude interconnection at depth, a hypothesis, on the other hand, that seems strengthened
by mud level time series correlations. The presence of shallow aquifers at a depth of 5 to 30 m is also supported by our field
data and allows us to delineate the boundaries of the shallow mud reservoir—pipes system and its overall shape. The shallow
aquifers may provide a temporary storage for the ascending gas and when fluid pressure in these aquifers exceeds the
tensional strength of the sedimentary rock, leakage of fluids to the surface would occur. In this case, if the gas–liquid ratio
is high, mud volcanoes develop into tall gryphons and tend to have a discontinuous activity with sudden eruptions of mud
after long periods of quiescence. This, together with the knowledge of shallow conduits localization has an important implication
for site safety in proximity to the mud volcanoes. Our inferences based on mud level relationships to mud extrusion
dynamics can be applied to lower risk in other mud volcanoes areas of the world with high geo-tourist visits, such as those
of Trinidad, Azerbaijan, and Colombia.