NDSHA: A new paradigm for reliable seismic hazard assessment.

A New Paradigm is needed for Reliable Seismic Hazard Assessment RSHA, not only from consideration of (a) the huge human losses experienced in the many recently destructive earthquakes worldwide; but also from (b) theoretical considerations of seismic wave generation and propagation phenomena through often non-homogeneous media within the earth's crust, particularly when large and more complex fault ruptures occur. The Neo-Deterministic Seismic Hazard Assessment (NDSHA) method, proposed some twenty years ago, is found to reliably and realistically simulate the wide suite of earthquake ground motions that may impact civil populations as well as their heritage buildings. The scenario-based NDSHA modeling technique is developed from comprehensive physical knowledge of: (i) the seismic source process; (ii) the propagation of earthquake waves; and (iii) their combined interactions with site effects. Thus, NDSHA effectively accounts for the tensor nature of earthquake ground motions: (a) formally described as the tensor product of the earthquake source functions and the Green's functions of the transmitting (pathway) medium; and (b) more informally described as mathematical arrays of numbers or functions (indices) "that transform according to certain rules under a change of coordinates." Importantly, NDSHA therefore uses all available information about the spacial distribution of large magnitude earthquake phenomena, including: (a) Maximum Credible Earthquake (MCE) – which is based on seismic history and seismotectonics; and (b) geological and geophysical data. Thus it does not rely on scalar empirical ground motion attenuation models (GMPEs), as these are often both: (a) weakly constrained by available observations; and (b) fundamentally unable to account for the tensor nature of earthquake ground motions. • "You never change things by fighting the existing reality. To change something, build a new model that makes the existing model obsolete." — Buckminster Fuller. • The Neo-Deterministic Seismic Hazard Assessment (NDSHA) method, proposed some twenty years ago, is found to reliably and realistically simulate the wide suite of earthquake ground motions that may impact civil populations as well as their heritage buildings. • The scenario-based NDSHA modeling technique is developed from comprehensive physical knowledge of: (i) the seismic source process; (ii) the propagation of earthquake waves; and (iii) their combined interactions with site conditions. • Thus, NDSHA effectively accounts for the tensor nature of earthquake ground motions. • Observations from recent destructive earthquakes in Italy: (i) Mw 5.9 Emilia 2012; (ii) Central Italy Mw 6.3 L'Aquila 2009; and 2016–2017 Seismic Crisis - Mw 6.1 Amatrice; Mw 5.9 Visso; Mw 6.5 Norcia; Mw 5.7 L'Aquila; and (iii) Mw 7.8 Nepal 2015 - have all confirmed the validity of NDSHA's approach and application. • Although damaging earthquakes cannot yet be predicted with ultimate precision , intermediate-term (several months) and middle-range (few 100 s km scale) predictions of main shocks above a pre-assigned threshold (based on seismicity "alarms" generated by interpretive algorithms like CN and M8) may be properly used for the implementation of low-key preventive safety actions. [ABSTRACT FROM AUTHOR]