Broadening Frontiers in Geoconservation: the Concept of Intangible Geoheritage Represented by the 1755 Lisbon Earthquake

Geodiversity refers to the variety of geological processes, forms, and materials that constitute and shape the Earth. Forms and materials displaying geoheritage contents are tangible objects, whether in situ like geosites, or ex situ like elements of geoheritage which include fossils, minerals, and rocks. They all result from geological processes, but these, in themselves, are essentially immaterial. The planet s history records some major events of worldwide importance, not only due the results they caused in Earth s geodiversity, but also because of their impacts on geological thinking. These include earthquakes and tsunamis, which can be directly experienced by humans. The great Lisbon earthquake and tsunami of 1st November 1755 is one of the most studied earthquakes in history. Its worldwide importance is not limited to the scientific and technical communities but it also affected many other human and social sciences. This earthquake corresponds to a geological process with geoheritage value that does not fit in the current concepts of geosite and element of geoheritage. Like the intangible cultural heritage, which refers to singular social processes, such type of geoheritage, which result of singular geological processes, requires the rise to a new concept in geoconservation: the intangible geoheritage. This concept designates geological processes representing milestones for the history of the geological sciences. Its relevance to other fields of knowledge allows the establishment of the so necessary bridge between scientific and humanistic culture.