Spatiotemporal seismic hazard and risk assessment of M9.0 megathrust earthquake sequences of wood-frame houses in Victoria, British Columbia, Canada

Megathrust earthquake sequences, comprising mainshocks and triggered aftershocks along the subduction interface and in the overriding crust, can impact multiple buildings and infrastructure in a city. The time between the mainshocks and aftershocks usually is too short to retrofit the structures; therefore, moderate‐size aftershocks can cause additional damage. To have a better understanding of the impact of aftershocks on city‐wide seismic risk assessment, a new simulation framework of spatiotemporal seismic hazard and risk assessment of future M9.0 sequences in the Cascadia subduction zone is developed. The simulation framework consists of an epidemic‐type aftershock sequence (ETAS) model, ground‐motion model, and state‐dependent seismic fragility model. The spatiotemporal ETAS model is modified to characterise aftershocks of large and anisotropic M9.0 mainshock ruptures. To account for damage accumulation of wood‐frame houses due to aftershocks in Victoria, British Columbia, Canada, state‐dependent fragility curves are implemented. The new simulation framework can be used for quasi‐real‐time aftershock hazard and risk assessments and city‐wide post‐event risk management.For this work, K.G. received funding from the Canada Research Chair program (950-232015) and the NSERC Discovery Grant (RGPIN-2019-05898), and M.J.W. received funding from the European Union's Horizon 2020 research and innovation program (No 821115, RISE: Real-Time Earthquake Risk Reduction for a Resilient Europe). L.Z. and M.J.W. appreciate the support from the London Mathematical Laboratory (http://lml.org.uk/). M.J.W. was also supported by the Southern California Earthquake Center (No. 10013); SCEC is funded by NSF Cooperative Agreement EAR-1600087 & USGS Cooperative Agreement G17AC00047

Energy-Based Seismic Risk Evaluation of Tall Reinforced Concrete Building in Vancouver, BC, Canada, under <i>M</i>_w9 Megathrust Subduction Earthquakes and Aftershocks

This article presents a seismic performance evaluation framework for reinforced concrete (RC) buildings, comprising shear walls and gravity frames. The evaluation is undertaken within a performance-based earthquake engineering framework by considering regional seismicity and site-specific ground motion selection. Different engineering demand parameters (EDPs), i.e., maximum interstory drift ratio (MaxISDR) and energy-based damage index, are considered as performance indicators. Various prediction models of EDPs are developed by considering four ground motion intensity measures (IMs), i.e., spectral acceleration at the fundamental period, Arias intensity, cumulative absolute velocity (CAV), and significant duration of ground motion. For this study, a 15-story RC building, located in Vancouver, BC, Canada, is considered as a case study. By using 50 mainshock and 50 mainshock–aftershock (MS-AS) earthquake records (2 horizontal components per record and bidirectional loading), non-linear dynamic analyses are performed. Subsequently, the calculated MaxISDRs and damage indices are correlated with suitable IMs using cloud analysis, and the most efficient IM-EDP prediction models are selected by comparing standard deviations (SDs) of the regression errors. The MaxISDR of the shear walls is less than 1% for the mainshock and MS-AS records. The energy-based damage index shows sensitivity to delineate impact of earthquake types and aftershocks. The CAV is showed to be the most efficient IM for the energy-based damage index

Inventaire parasitologique de l'Ethiopie : Helminthes des zébus adultes de la région de Kofélé (Arussi)

Les auteurs dressent la liste des helminthes recueillis à l'autopsie d'un lot de zébus adultes originaires de la région de Kofélé (Sud de la Province de l'Arussi, Ethiopie). Ils observent, dans le tractus digestif et dans le foie, la présence de nombreux Trématodes et Nématodes fréquemment associés entre eux. Il en résulte un polyparasitisme qui, dans 20 p. 100 des cas environ, s'avère particulièrement grave. Par ailleurs, ils retrouvent, là encore, les 2 zoonoses majeures si répandues en Ethiopie: la ladrerie à Cysticercus bovis avec un taux d'infestation de 14,6 p. 100 et l'echinococcose à Echinococcus polymorphus qui affecte plus de 50 p. 100 des animaux autopsiés et provoque parfois leur mort par cachexi

Riparian buffer strips influence nitrogen losses as nitrous oxide and leached N from upslope permanent pasture

Riparian buffer strips can have a significant role in reducing nitrogen (N) transfers from agricultural land to freshwater primarily via denitrification and plant uptake processes, but an unintended trade-off can be elevated nitrous oxide (N2O) production rates. Against this context, our replicated bounded plot scale study investigated N2O emissions from un-grazed ryegrass pasture served by three types of riparian buffer strips with different vegetation, comprising: (i) grass riparian buffer with novel deep-rooting species, (ii) willow (young trees at establishment phase) riparian buffer, and (iii) deciduous woodland (also young trees at establishment phase) riparian buffer. The experimental control was ryegrass pasture with no buffer strip. N2O emissions were measured at the same time as total oxidized N in run-off, and soil and environmental characteristics in the ri parian buffer strips and upslope pasture between 2018 and 2019. During most of the sampling days, the no-buffer control treatment showed significantly (P < 0.05) greater N2O fluxes and cumulative N2O emissions compared to the remainder of the treatments. Our results also showed that the grass riparian buffer strip is a sink of N2O equivalent to − 2310.2 g N2O-N ha− 1 day− 1 (95% confidence interval:− 535.5 to 492). Event-based water quality results obtained during storms (12 November 2018 and 11 February 2019) showed that the willow riparian buffer treatment had the highest flow-weighted mean N concentrations (N-FWMC) of 0.041 ± 0.022 and 0.031 ± 0.015 mg N L− 1, when compared to the other treatments. Our 9-month experiment therefore, shows that ri parian buffer strips with novel deep-rooting grass can therefore potentially address emissions to both water and air. The results imply that over a shorter timeline similar to the current study, the grass riparian buffer strip can potentially address N emission to both air and water, particularly when serving a permanent pasture in similar settings as the current experiment.Fil: Dlamini, J.C. Crop and Climate Sciences. Departament of Soil; Sudáfrica. Rothamsted Research. Sustainable Agriculture Sciences; Reino Unido. University of Pretoria. Department of Plant and Soil Sciences; SudáfricaFil: Cardenas, L.M. Rothamsted Research. Sustainable Agriculture Sciences; Reino Unido.Fil: Tesfamarian, E.H. University of Pretoria. Department of Plant and Soil Sciences; SudáfricaFil: Dunn, R.M. Rothamsted Research. Sustainable Agriculture Sciences; Reino Unido.Fil: Loick, N. Rothamsted Research. Sustainable Agriculture Sciences; Reino Unido.Fil: Charteris, A.F. Rothamsted Research. Sustainable Agriculture Sciences; Reino Unido.Fil: Cocciaglia, L. Università degli Studi di Perugia. Dipartimento di Scienze Agrarie, Alimentari e Ambientali; ItaliaFil: Vangeli, Sebastián. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Clima y Agua; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Ingeniería Agrícola y Uso de la Tierra. Cátedra de Manejo y Conservación de Suelo; ArgentinaFil: Blackwell, M.S.A. Rothamsted Research. Sustainable Agriculture Sciences; Reino Unido.Fil: Upadhayay, H.R. Rothamsted Research. Sustainable Agriculture Sciences; Reino Unido.Fil: Hawkins, J.M.B. Rothamsted Research. Sustainable Agriculture Sciences; Reino Unido.Fil: Evans, J. Rothamsted Research. Computational and Analytical Sciences; Reino UnidoFil: Collins, A.L. Rothamsted Research. Sustainable Agriculture Sciences; Reino Unido