The SISFRANCE database of historical seismicity. State of the art and perspectives

The SISFRANCE database aims to collect and interpret archives relating the historical seismicity in metropolitan France. The database presently contains some 12,500 documents that allow to define 108,832 macroseismic data points, for a total of 6427 events, of which 5743 can be qualified as real earthquakes. Although half of these events are and will probably remain poorly known, completing our knowledge of historical earthquakes remains a fundamental element for the definition of seismic hazard and the understanding of seismicity in France and low to moderate seismicity regions in general. The first aim of this paper is to explain the state of the art of the database and remind end users how the limits introduced by the necessary interpretation of archival data are translated into quality factors that should be carefully considered when using such data for seismotectonic and seismic hazard purposes. Originally built as part of the necessary datasets to define the seismic hazard for nuclear facilities, the SISFRANCE database is the result of 40 years of work within a consortium bringing together the French civil nuclear operator (EDF), the French geological survey (BRGM), and the French institute of nuclear safety (1RSN). SISFRANCE is also the heir to archival research carried out since the second half of the 19th century, thus constituting the richest collection of data related to historical seismicity in France. The second aim of this paper is to explain to end users the current state of archival research within the SISFRANC!) consortium, present avenues for future research strategies, and list potential improvements of the database structure. Archival research within the SISFRANCE consortium, no longer carried out by a dedicated historian since 2018, is presently being pursued by engaging individual researchers or academics, focusing research on specific archives and regions, as well as by developing data-mining techniques to exploit the increasing wealth of accessible numerical archives. Given the new impetus of French governmental research agencies that encourage transdisciplinarity research, SISFRANCE is also pursuing the idea of further engaging the academic community of historians and seismologists, presently greatly underrepresented in the field of historical seismicity in spite of the importance of this data, fundamental for any seismotectonic and seismic hazard study in France.