UNAM specialists identify 'mud well' phenomenon in Michoacán, Mexico

A geological phenomenon resembling a "boiling little well" has appeared in El Salitre, a community in Michoacán, Mexico, prompting specialists from the National Autonomous University of Mexico (UNAM) to investigate. The event, initially reported by residents on May 26, 2026, occurred in the exterior patio of a home and was characterized by cracked earth with apparent geothermal activity. Local officials described it as a "pocito hervidor" that expelled water, mud, and steam, leading to initial speculation that it was a geyser. However, UNAM experts have clarified that it is not a geyser or an active volcano, but rather a manifestation of hydrothermal activity. Dr. Ruth Esther Villanueva Estrada, a researcher at UNAM's Michoacán Unit of the Institute of Geophysics, explained that the phenomenon is linked to the circulation of hot fluids deep beneath the Earth's surface. El Salitre is situated above the Ixtlán fault, a geological structure that facilitates the movement of these hot fluids upwards. During their inspection, specialists observed the release of steam, hot water, and gases such as ammonia, hydrogen sulfide, and carbon dioxide through subsurface fractures. They also identified approximately 11 mud pools with temperatures around 86 degrees Celsius. Michoacán is part of the Trans-Mexican Volcanic Belt, one of Mexico's most geologically active regions, with scientific records of hydrothermal manifestations dating back to 1906. UNAM specialists are advising the local population to implement contingency plans, including monitoring the ground for new cracks or swelling, avoiding areas with steam emissions or high temperatures, keeping children and pets away from the openings, and reporting any significant activity to municipal authorities.

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This phenomenon is not a geyser, let alone an active volcano, but rather the presence of hydrothermal activity in the area.