Natural hydrogen exploration is now active in various places of the world. Onshore, sub circular depressions without vegetation appear to be a good proxy for hydrogen emanations but they are neither mandatory neither unambiguous. Vegetation indexes computed from multispectral satellite image analysis have been successfully tested in Namibia to map these H2 emitting subcircular depressions and they highlight a ring of dense vegetation around the depressed area without vegetation. Application to the Sao Francisco basin in Brazil and especially to the area where emitting structures have been monitored, based on Landsat multispectral images and their processing through NDVI and SAVI indexes highlights these rings of healthy vegetation. Geometrical data, such as elevation or slope allows also us to define a geometry for these structures. These characteristics are interesting since they likely correspond to an average of the signal at the opposite of the H2 content in the soil that are clearly related to short term pulse and H2 and which vary over the day.
We will present the geometry of the area affected by H2 emission as seen by these different methods (geometry, infrared) and compare them to the data of the permanent monitoring that has been done. The conclusions will help to know what could be done from remote sensing versus field acquisition and monitoring.