The reliable quantification of earthquake ground motions as a function of magnitude, distance, and frequency is directly linked to seismic hazard analysis and shaking scenarios for engineering, civil protection purposes, and systems designed to provide earthquake rapid response and early warning. Realistic modeling of earthquake ground motions can be achieved only when the rupture process on causative fault, the medium property of the seismic wave path, and the local site condition are accurately represented.
The main goal of SECURE is to study earthquake ground motion characteristics through innovative techniques to improve ground motion predictions for seismic hazard mitigation in the Central Apennines.
SECURE is interested in exploring the links between earthquake source physics, wave propagation, and ground motion variability on local and regional scales, revealing the geological and seismic structures (e.g., basins and topography) and improving existing crustal velocity models in the Central Apennines. SECURE aims to investigate the inherent variability of ground motion in space and time and examine how the source, path, and site properties (e.g., stress drop, Q(f), κ) modify the earthquake ground motions during the seismic sequences. SECURE intends to develop data-driven non-ergodic and physics-based ground-motion models that consider regional and temporal variations (before, during, and after large earthquake sequences) and provide ground motion parameters and time histories for engineering applications.
Under the SECURE framework, we will generate physics-based hybrid and 3D numerical broadband simulations of ground motions at thousands of sites providing an alternative tool to the empirical data and models.
Integrating empirical and synthetic ground motion parameters is one of SECURE’s main interests, particularly in areas characterized by high hazard levels as near-fault regions, where shaking is most significant, and few recorded data are available from large earthquakes.
SECURE will evaluate, test, and validate the predicted ground motions against the seismic recordings and macroseismic intensity (MI) data available in the study area. The ranking scheme will be used in accordance with well-established engineering metrics and rules (e.g., fragility curves for different types of structures as a function of the ground motion intensity measure of interest) to provide direct means for engineering applications.
A systematic and multidisciplinary study, together with a large amount of available data, will help comprehend the connection among physical parameters of the Earth, capture the complex physics of earthquake rupture and 3D regional wave propagation, and site responses and improve current techniques to better predict ground motions for future large earthquakes in the Central Apennines. The strategy proposed in SECURE can easily be transferred and applied to other seismically active regions.
SECURE is conceived from the desire to answer the following questions:
- How should we improve the ground motion predictions in central Italy?
- What is the impact of earth structure, basins, topography, source rupture heterogeneity (kinematic, dynamic, and geometrical), and seismic wave attenuation on the estimated ground motions at a given site?
- Do non-ergodic ground-motion models, including spatial and temporal non-stationarity, improve the prediction capability of ground shaking, also during a seismic sequence?
- Can physics-based earthquake ground-motion simulations be defined as ground-motion prediction?
- Is it possible to decrease the variability by calibrating temporal non-stationary GMM that implicitly includes parameters describing the dynamic of rupture processes (e.g., stress drop, apparent stress)?
- Can we validate the empirical relationships between macroseismic intensity and recorded ground motion using statistical tests?
- Can we develop a validation test for GMMs for performance assessment in engineering applications?
- Do the regionalized hybrid GMMs derived from the simulations and non-ergodic predictions perform better than existing GMMs in Central Italy?
As one of the essential points, SECURE will encourage research activities on ground motion modeling and validation topics integrating innovative and consolidated approaches, sharing the knowledge and experiences with several international/national researchers and experts from Lawrence Livermore National Laboratory, LLNL (USA), Centro de Investigacion Cientifica y de Educacion Superior de Ensenada (Mexico), Helmholtz Centre Potsdam, GFZ and University of Mainz (Germany), University of Bogazici, KOERI (Turkey), and University of Prague (Czech Republic), University of Calabria, UNICAL, University of Federico II, Napoli. SECURE will bring together 29 INGV and ten external national/international researchers from different Institutes/Universities/Departments. SECURE will also collaborate with other ongoing projects on various topics that may offer valuable knowledge in the study area.