Seismic ground motion and Site-City interaction

Seismic ground motion is classically described as the terms of the earthquake source (e.g., magnitude, fault type...), wave propagation (e.g., distance, attenuation...) and site conditions (e.g., Vs30, amplification function...). The latter produced much of the variability in ground motion and damage observed. In particular, in the event of strong earthquakes, the activation of non-linear processes is usually observed, which completely change the response of the site, on different time scales. Key scientific questions remain as to how to establish the constitutive equations for site degradation and recovery (creep), and how to take these processes into account when predicting ground motion.

In cities, an until now ignored urban component f(U) must be also considered to the prediction model, associated with the presence of the urban layer (initially described by the site-city effect). The collective effect of buildings (also defined in physics through the concept of meta-materials) questions the validity in the city of ground motion models and the characterization of site effects, and ultimately on the design of structures.

Why not also imagine earthquake-proof urban planning, i.e. cities that, organized according to a particular pattern, could create anti-seismic protection.

Reference

• Guéguen P., Roux P., Colombi A. 2022. Urban Seismology : Experimental Approach to Soil–Structure Interaction Towards the Concept of Meta-city.https://doi.org/10.1002/9781119887690.ch5]
• Kaklamanos, J., Cabas, A., Parolai, S., & Guéguen, P. (2021). Introduction to the special section on advances in site response estimation. Bulletin of the Seismological Society of America, 111(4), 1665-1676.

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Suggested background music :
Arcade fire - The suburbs (2010)
La Femme - Sur La Planche (2013)