Future trends in paleoseismology: Integrated study of the seismic landscape as a vital tool in seismic hazard analyses

This paper forms the Introduction to this Special Issue of Tectonophysics, devoted to selected scientific research presented during events sponsored by the INQUA Subcommission on Paleoseismicity in the past few years. In this note, we summarize the contents of the contributed papers and use the issues they raise to review the state-of-the-art in paleoseismology from a Quaternary geology perspective. In our opinion, the evolution of paleoseismological studies in the past decade clearly demonstrates that in order to properly understand the seismic potential of a region, and to assess the associated hazards, broad-based/multidisciplinary studies are necessary to take full advantage from the geological evidence of past earthquakes. A major challenge in future paleoseismic research is to build detailed empirical relations between various categories of coseismic effects in the natural environment and earthquake magnitude/ intensity. These relations should be compiled in a way that is fully representative of the wide variety of natural environments on Earth, in terms of climatic settings, Quaternary tectonic evolution, rheological parameters of the seismogenic crust, and stress environment. For instance, available data indicate that between earthquake magnitude and surface faulting parameters different scaling laws exist, and they are a function of the local geodynamic setting (including style of faulting, typical focal depths, heat flow). In this regard, we discuss in some detail the concept of seismic landscape, which provides the necessary background for developing paleoseismological research strategies. The large amount of paleoseismological data collected in recent years shows that each earthquake source creates a signature on the geology and the geomorphology of an area that is unequivocally related with the order of magnitude of its earthquake potential. This signature is defined as the seismic landscape of the area (e.g., Serva, L., Vittori, E., Ferreli, L., Michetti, A.M., 1997. Geology and seismic hazard. In: Grellet, B., Mohammadioun, B., Hays, W. (Eds.), Proceedings of the Second France–United States Workshop on Earthquake Hazard Assessment in Intraplate Regions: Central and Eastern United States and Western Europe, October 16, 1995, Nice, France, 20–24, Ouest Editions, Nantes, France; Michetti, A.M., Hancock, P.L., 1997. Paleoseismology: understanding past earthquakes using quaternary geology Journal of Geodynamics 24 (1–4), 3–10). We then illustrate how this relatively new framework is helpful in understanding the seismic behavior of faults capable of producing surface faulting and provides a comprehensive approach for the use of paleoseismicity data in earthquake hazard characterization.