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The results of a preliminary U-series study of the timescale of magmatic processes at Vesuvius are presented. Phonotephrites of the 1944 eruption of Vesuvius show 0–15% 230 Th – 238 U and 350–1150% 226 Ra – 230 Th disequilibria. Apparent U–Th internal isochrons for a lava and a cumulate nodule suggest crystal residence times of 12 and 39 ka, respectively. A tephra sample shows isotopic heterogeneity, possibly related to mixing of younger crystal-laden melt and older crystals giving apparent U–Th ages of 0.4 and 18 ka, respectively. Mineral 226 Ra – 230 Th disequilibria on Ba-normalised internal isochron diagrams suggest Ra–Th ages of 1730–3300 years for the same rocks and phenocrysts. Minor 226 Ra / 230 Th heterogeneity between minerals and groundmass (or whole rock) is evidence of open-system Ra–Th behaviour. This heterogeneity suggests that there have been recent, post-crystallisation changes in melt composition that affected 226 Ra more than 230 Th . Continued crystallisation in a Ra-enriched magma has subsequently resulted in Ra–Th disequilibria probably as a result of addition via a fluid-rich phase. Magma differentiation, residence time, transport, and pervasive gas addition at Vesuvius apparently occur over geologically short periods.

Neo-deterministic seismic hazard assessment (NDSHA) is based on the geophysical and seismotectonic features of a region and adopts a multiscale approach (i.e., regional and local) and multiscenario approach. This methodology has been successfully applied to many regions worldwide and, for the purpose of seismic microzoning, to several urban areas, including lifelines, relevant buildings, and cultural heritage sites. NDSHA naturally supplies realistic time series of ground motion, including reliable estimates of ground displacement readily applicable to seismic isolation techniques, useful to preserve historical monuments and relevant man-made structures. In this way, it creates a viable bridge between the seismological and the engineering community. We discuss here its application to the cities of Rome (where the first seismic microzonation study was developed using NDSHA), Valparaiso (where one of the first multihazard study was developed), and Trieste (where the first NDSHA study for seismic verification was conducted). This contribution should be intended as a sort of an illustrative, but definitely not exhaustive, view in space and time through possible NDSHA applications at a local scale.

In recent years, probabilistic seismic hazard assessment (PSHA) has been the most common procedure to evaluate the potential effects of future earthquakes. It assesses the probability that some measure of ground motion intensity (e.g., the peak ground acceleration) exceeds some threshold during a given period of time (most commonly 10% in 50 years’time). In Europe and the Mediterranean region, different efforts starting in the 1990s have provided several regional hazard models at the continental scale (e.g., Jiménez et al., 1999, 2001; Giardini et al., 2003) with the latest model in Woessner et al. (2015) deriving a complete set of harmonized seismic hazard results and associated uncertainties for Europe. Site studies for nuclear power plants were the onset for the development of seismic hazard in Spain at the beginning of the 1970s. At that time, the existing regulations demanded classical deterministic analysis. Therefore, only a few works included either statistical or probabilistic approaches, which later on were widely applied in most of the regional hazard studies carried out in Spain in the 1980s and 1990s (see, e.g., Martín, 1984; Muñoz et al., 1984; Litehiser and Marrone, 1991, among others). It was for the first time in 1994 when the update of the Spanish Building Code incorporated a probabilistic seismic hazard map to define the basic seismic action (Martín, 1995). Studies incorporating alternative statistical analysis, including Bayesian techniques, of hazard parameters were also applied in the last 1980s and early 1990s (see, e.g., García-Fernández et al., 1989; Egozcue et al., 1991)

The neo-deterministic seismic hazard assessment (NDSHA), developed at the University of Trieste (UT), has emerged as an attractive tool for predicting the ground motion for given seismic sources and known earth structure. This method, a computationally intensive procedure, is based on physical modeling of wave propagation and seismic source process. Under ongoing research and academic collaboration program between UT and BUET, NDSHA studies have been performed for Bangladesh. This chapter briefly presents significant results obtained under this initiative. Results obtained are compared with the seismic zoning map in the updated Bangladesh National Building Code (BNBC-2020). The seismicity and seismo-tectonics of Bangladesh and the adjoining region are also briefly discussed.