Sponsored by:   Date: February 22, 2018 Speaker: Caitlyn Hall and Leon van Passen Topic: Bio-based Solutions to Mitigate Geologic Hazards Abstract: Every structure in the community, be it a building or a bridge, a house or an office, relies on the strength and stability of the ground beneath it and around it to keep it safe and prevent loss of life. As urbanization increases, large centralized populations and infrastructure are made increasingly vulnerable to threats by natural disasters. Some of these hazards, such as flooding, are further exacerbated by rising sea levels due to climate change and subsidence in densely populated cities. Taking preventative action can reduce the need for extreme emergency relief and city rehabilitation from natural hazards, which in extreme cases, like Hurricane Katrina, can be on the order of $160 billion for a single event. Current solutions to reduce risk are costly or impractical to be applied at large scale or underneath existing facilities. Often they involve the use of significant resources that can significantly contribute to greenhouse gas emissions, such as Portland cement. Current research at the Center for Bio-mediated and Bio-inspired Geotechnics (CBBG) aims to learn from nature and develop cost-effective and sustainable bio-based technologies to strengthen earthen structures and reduce risk of failure. For example, microbially induced desaturation and precipitation of calcium carbonate (MIDP) is a biochemical process, which can be used in two ways to mitigate earthquake induced liquefaction: 1) Precipitation of calcium carbonate in the pore space could be used to increase the strength and stiffness of silty sands and 2) Biogenic gas production could be used to reduce pore pressure build-up from external forces and reduce permeability. This contribution provides an overview on recent advances, including experimental studies at various scales, using both specific micro-organisms and enrichment of indigenous microbial communities, theoretical and numerical studies aimed to improve fundamental insight on the biogeochemical conversions and coupled to the hydro-mechanical properties. Besides the scientific and technological advances, also market potential, sustainability performance and other factors, which determine the successful implementation of these new bio-based technologies are discussed.