Díaz Díaz, Jesús IldefonsoTalenti, Giorgio2023-06-202023-06-2020040033-455310.1007/s00024-004-2517-2https://hdl.handle.net/20.500.14352/49603A mathematical model of general gas emitting systems is derived, and a sample of relevant mathematical results is offered. The present paper indicates that shallow subsurface gas sources in typical volcanic areas can be located if appropriate physico-chemical measurements are made on the Earth’s surface and put to use.engjournal articlehttp://www.springer.com/birkhauser/geo+science/journal/24open access512.7Subsurface sourceSurface measurementPartial differential equations of parabolic typeFree boundaryObstacle problemA priori boundGeometria algebraica1201.01 Geometría Algebraica