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Tailings impoundments are often prone to failure due to various causes related to complex loading conditions. For instance, tailings impoundments can fail during or after a seismic event, mainly because of the liquefaction of loose, cohesionless tailings. To improve the seismic stability of impoundments, the density of the tailings can be increased or waste rock inclusions (WRI) can be added in the impoundment. This paper presents the results of numerical analyses of the impoundments loaded with a variety of ground motions with different frequencies, scaled at two different levels of intensity representative of two mining regions of Eastern Canada. The results show that the conventional impoundments are subjected to medium to high displacements at the end of shaking; these show a high probability of rupture during the earthquake or in the post-seismic phase. Tailings densification can decrease the volume of liquefied tailings and displacements during the seismic phase but does not significantly reduce the probability of post-seismic failure. WRI can slightly reduce the volume of liquefied tailings, depending on the intensity of the motions, but the reinforcement reduces significantly the lateral displacements; impoundments with WRI show even better performances during the post-seismic phase. The use of WRI is deemed a good approach to ensure the seismic stability of tailings impoundments and reduce the risk of seismically induced failure. [ABSTRACT FROM AUTHOR]

While damping devices can provide supplemental damping to mitigate building vibration due to wind or earthquake effects, integrating them into the design is more complex. For example, the Canadian code does not provide building designs with inline friction dampers. The objective of this present article was to study the overstrength, ductility, and response modification factors of concrete frame buildings with inline friction dampers in the Canadian context. For that purpose, a set of four-, eight-, and fourteen-story ductile concrete frames with inline seismic friction dampers, designed based on the 2015 National Building Code of Canada (NBCC), was considered. The analyses included pushover analysis in determining seismic characteristics and dynamic response history analysis using twenty-five ground motion records to assess the seismic performance of the buildings equipped with inline seismic friction dampers. The methodology considered diagonal braces, including different 6 m and 8 m span lengths. The discussion covers the prescribed design values for overstrength, ductility, and response modification factors, as well as the performance assessment of the buildings. The results revealed that increasing the height of the structure and reducing the span length increases the response modification factors. [ABSTRACT FROM AUTHOR]

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Tsunamis from earthquakes of various magnitudes have affected Cascadia in the past. Simulations of Mw 7.5–9.2 earthquake constrained by earthquake rupture physics and geodetic locking models show that Mw ≥ 8.5 events initiating in the middle segments of the subduction zone can create coastal tsunami amplitudes comparable to those from the largest expected event. Our rupture and tsunami simulations reveal that the concave coastline geometry of the Pacific Northwest coastline focuses tsunami energy between latitudes 44° and 45° in Oregon. The possible coastal tsunami amplitudes are largely insensitive to the choice of slip model for a given magnitude. These results are useful for identifying the most hazardous segments of the subduction zone and demonstrate that a worst‐case rupture scenario does not uniquely yield the worst‐case tsunami scenario at a given location. Plain Language Summary: Offshore earthquakes along the Pacific Northwest coast of the U.S. and Canada (Cascadia region) can have magnitudes as high as 9.2, as was probably the case for an earthquake in the year 1700 CE that resulted in a large tsunami in Cascadia and across the Pacific Ocean. To learn more about the future tsunami hazard in the region, we design computer models of tsunamis from a wide range of earthquake scenarios. We find that almost regardless of the earthquake source details, events larger than magnitude 8.5 near the coast of Oregon can create large and widespread tsunamis along the US west coast. These are consequences of the geometry of offshore earthquake faulting and the concave shape of coastline in the region. Key Points: A Mw = 8.5 event in central Cascadia (Oregon) can create coastal tsunami amplitudes comparable to those from the largest possible eventThe concave coastline contributes to larger coastal tsunami amplitudes in central CascadiaThe choice of slip model does not significantly affect the distribution of coastal tsunami amplitudes in Cascadia [ABSTRACT FROM AUTHOR]