The Maccalube d’Aragona mud volcano Monitoring System

We describe the design, implementation, and evaluation of a combined monitoring tasks to better understand a mud volcano (MV) activity, in the framework of INGV Pianeta Dinamico – MT-PROMUD project. The study site is the Maccalube d’Aragona (Sicily, Italy) protected reserve, hosting a MV field. Maccalube MV is characterized by continuous low-energy emissions of mud, water and gases (mainly CH₄) as well as episodic paroxysmal eruptions. During the 2014 paroxysm, two children were buried by the mud fallout, and the site has been under judicial seizure for several years, until early 2025.

Starting from 2023, we carried out a series of pilot studies and consultations to design a monitoring network and to plan simultaneous acquisitions of multidisciplinary signals and spot surveys. The resulting monitoring strategy includes: 1) permanent instrumentation, acquiring in a continuous mode, seismic signals, meteorological parameters, soil temperature, apparent volumetric water content, Temperature, Electric Conductivity and water column pressure (CTD) in the mud pool; 2) mobile devices, for spot acquisitions of mud emitting vents positions (GNSS), tromographies, hydrophone recordings for acoustic soundscape characterization, apparent soil volumetric water content and environmental radioactivity measures, (focused on ²²²Rn and ²²⁰Rn emissions), and geoelectrical tomographies; 3) sample collections of plants  for metabolomic analysis, water and gas emitted from MV and mud pools for chemical and isotopic analyses, mud for magnetic, micropaleontological and mineralogical investigations. All spot surveys were documented with photographic reportages.

This monitoring system enabled the acquisition of high quality and unique data associated with the paroxysmal eruption of 29 August 2025, as well as variations in MV activity in occasion of a local earthquake.

Our combined and multidisciplinary approach provided a comprehensive picture of mud volcanoes functioning and can serve as a model to assess the need for future monitoring of other mud volcanoes.