This paper is related to the study of the ion density recorded by the low altitude satellite DEMETER. In a first time there is an automatic search for ionospheric perturbations in the complete satellite data set of ion densities. Then perturbations due to known ionospheric phenomena (for example. solar activity) are eliminated as well as perturbations not above a seismic zone. https://chefesquipmenters.shop/product-category/european-dinner-forks/