Laguna del Maule is a volcanic field in the Andes mountain range of Chile. The volcanic field covers an area of 500 square kilometres (190 sq mi) and features at least 130 volcanic vents. The field gets its name from Laguna del Maule, a lake surrounded by cones, lava domes, lava coulees and lava flows. The field's volcanic activity began 1.5 million years ago during the Pleistocene. Three major caldera-forming eruptions took place in the volcanic field prior to the last glacial period. Volcanic activity has increased during the postglacial era. In pre-Columbian times, the field was a regionally important source of obsidian. Today geothermal phenomena occur at Laguna del Maule. Between 2004 and 2007, ground inflation began in the volcanic field, indicating the intrusion of a sill beneath it. The rate of inflation is faster than those measured on other inflating volcanoes, which has created concern about the potential for impending large-scale eruptive activity. (Full article...)