Investigating Fluid Flow and Subsurface Structure of Saribogha Mud Volcano Through A Multi-Geophysical Survey

Mud volcanoes are sedimentary structures that extrude clay-rich material driven by fluid overpressure. Their subsurface properties, including porosity, permeability, and fluid content, vary laterally and vertically, influencing fluid circulation and eruptive behaviour. Imaging these heterogeneities is essential to assess environmental and geological hazards, such as landslides, sudden gas emissions, and ground deformation.

A multi-method geophysical survey was conducted on the Saribogha mud volcano (Azerbaijan), selected for its numerous small eruptive surface features (pools, salsa lakes, and gryphons). The dataset includes three electrical resistivity tomography (ERT) profiles, 20 time-domain electromagnetic (TDEM) soundings, and a gravity survey covering the entire area.

The data show low noise levels and are consistent with typical mud-volcano responses. The gravity map reveals an anomaly near zero along an east–west axis, with higher positive values to the north and south. A localized negative anomaly occurs to the west along the axis, coincident with an abundance of surface effusive features. This area also corresponds to highly conductive zones in both ERT and TDEM datasets, which, despite differing resolutions, show similar conductivity patterns. At greater depth (~60 m), both methods show a contrast between a less conductive northern sector and a more conductive southwestern sector. Although the geophysical contrasts are weak, positive gravity anomalies and less conductive zones likely reflect sandstone host rock or consolidated mud, while negative anomalies and more conductive areas indicate fluid accumulation and pathways.

We propose a conceptual model in which deep fluids rise vertically from the southwestern sector, possibly from a shallow mud chamber, before spreading laterally beneath the surface. Interaction with a shallow perched aquifer, partly recharged by rainfall, may contribute to the high-water content of surface features. Ongoing gravity modelling aims to test the proposed mud-flow conceptual model by exploring subsurface geometry and density contrasts.