Lusi is near the arc of volcanoes in Indonesia where geothermal activities are abundant. The nearest volcano, the Arjuno-Welirang complex, is less than 15 km away. The hot mud suggests that some form of geothermal heating from the nearby magmatic volcano may have been involved. The hot water and steam flowing from the vent, the location of Lusi near a magmatic volcano complex and its recharge system indicates that Lusi may be a geothermal phenomenon.