The Role of Creeping Mud Flows and the Hidden Dynamics of Mud Volcanism. Examples from Azerbaijan

Mud volcanoes are large geological phenomena that can exhibit spectacular mud flows extending for kilometres in length. Traditionally, these flows have been linked to major eruptive events with extensive mud extrusions. Recently it has been suggested that a significant number of such flows are instead formed by creeping flow processes, a mechanism similar to what is observed at warm-based glaciers. The proposed model suggests that the creeping is promoted/accelerated by two main factors: (1) episodic mud effusion that increases gravitational loading and periodically reactivates the mud flow for several months after an eruptions; and (2) a fluid-rich basal layer that lubricates the movement of the whole flow.

Azerbaijan hosts the highest concentration of large-scale mud volcanoes on Earth. To determine the dynamics of the creeping phenomena and their characteristics, we selected 47 large mud volcanoes across onshore Azerbaijan. For each one, we analysed historical satellite imagery from Google Earth and integrated field observations at four different structures.

Our study reveals that 19 of the 47 mud volcanoes show measurable creeping displacements of preexisting and paleo-mud flows. Rates range from a few metres to tens of metres per decade with movements associated with kilometre-sized mud flows. The rate and extent of this movement vary among individual structures and appear to be induced by factors such as eruption frequency, slope gradient, and/or subsurface fluid availability.

Our observations indicate that the most important deformations are prompted by eruptive events, with a substantial decrease, and occasional halting, over time. Our study emphasises that post-eruptive adjustment mechanisms shape the long-term evolution of kilometre-sized mud flows.

Some of the studied mud volcanoes host infrastructures, dispersed settlements, and are located in the vicinity of populated areas, representing geohazards for those communities. Analogous processes are also expected to occur at large mud volcanoes in other settings worldwide as well as in other planetary bodies. These findings highlight the need for broader studies, continuous monitoring, and to greater awareness of the potential risks that this process may represent.