Physical and geochemical characteristics of land mud volcanoes along Colombia's Caribbean coast and their societal impacts

The Caribbean coast is characterized by the presence of mud volcanoes, a secondary phenomenon of volcanismsimilar to mud diapirs for its development and evolution, but different in terms of geological features and forms.These mud volcanoes are often located close to tectonic faults and oil and gas deposits. Their geological context isdominated by the presence of clay sediments and brackish water, that favors the decomposition of organic materialand the formation of methane. Mud volcanoes can thus be an important reservoir of hydrocarbons. Thispaper aims to fill the existing gap in the knowledge of mud volcanoes (MVs) of Colombia. We analyze the physicaland geochemical characteristics of nine onshore mud volcanoes located in the Departments of Atlántico (LaLaguna), Bolívar (Las Palomas, La Bonga, Santa Catalina, Yerbabuena, Clemencia, and Membrillal), Cordóba (LosOlivos), and Magdalena (Cañaveral). These structures present a kaolinitic composition, except for La Lagunamud volcano in which smectite is predominant. Apart from tectonic processes, this influences the shape andsize of MVs and, also, the type and frequency of eruptions. The abundance of methane in all sites confirms thethermogenic origin of these structures. MVs are often considered landscape attractions as well as a therapeuticresources, but unfortunately they also represent a serious risk for the local communities, due to the frequent unexpected,eruptions, sometimes accompanied by the release of toxic gases or by landslides, that can damage the infrastructures andhurt the population living in the area. The MVs are classified into five vulnerability classesusing a novel synthetic index which could improve the understanding of risks associated with the presence ofMVs in proximity to towns and infrastructures.