Mud volcanoes : a review

Sammanfattning: Mud volcanoes are pathways through and within which buried argillaceous loose sediments and lithified rocks are altered and transported back to the Earth’s surface. The types of mechanisms of formation, maintenance and triggering of this natural, sedimentary recycling-process vary largely whereby external as well as internal properties of mud volcanoes differ greatly. Sizes range from millimetres to kilometres, shapes from caldera-like collapse structures to protruding cones, grade of activity from hardly noticeable to hazardous marked by kilometre-high flares of fire and emissions from flowing, low-viscosity and water-dominated to high-viscosity, toothpaste-like muds. Typically, mud volcanism also involve voluminous emissions of methane and carbon dioxide. Of the roughly 2000 onshore and offshore mud volcanoes known today, most are located and act either along active, convergent plate boundaries although several examples are known from passive continental margins and continental interiors marked by high sediment accumulation rates. Evidently, mud volcanism is a pressure-dependant process. As relatively unexplored windows into the Earth’s interior, worldwide occurring hazardous geological features and significant contributors to global atmospheric and hydrospheric gas budgets, mud volcanoes are of high scientific, economical, environmental and societal interest.