Seismic Muffler Protection Of Critical Infrastructure From Earthquakes

Each year, large ground motions from earthquakes cause infrastructure damage and losses worldwide. Moreover, thousands of earthquake-related deaths occur annually that are caused by collapsing buildings and structures. Although earthquake engineering technologies evolved over many years to attenuate the effects of destructive seismic waves, significant damage and fatalities still occur. Here we present a novel concept that redirects and attenuates hazardous seismic waves by implementing an engineered seismic muffler. The muffler design is inspired from that of an acoustic muffler that dissipates elastic wave energy in a fluid. The seismic muffler uses a vertically oriented subsurface V-shaped structure constructed in geological media. This structure uses sloping-opposing boreholes or trenches to form the muffler walls and is designed to reflect and divert direct surface waves as a barrier while dissipating body and converted waves that travel from depth vertically upward into the muffler duct. Analytical and computational seismic wave propagation simulations suggest a seismic muffler can effectively reduce ground motion and scatter broadband seismic waves at the ground surface directly above the muffler (i.e., the designated protection region). Simulations are compared for validation with experimental data obtained from bench-scale blocks containing machined borehole arrays and trenches and are then scaled to an earth-sized model. Findings suggest the effects of a devastating seismic energy magnitude 7.0 M-e earthquake can be reduced to less damaging magnitudes, 4.5 M-e (summed surface wave), and 5.7 M-e (summed surface wave and muffler leakage). Results show seismic muffler structures significantly reduce the impact of the peak ground velocity of the surface wave, but seismic transmission through the muffler base at depth has marginal effects.