Abstract Characterized by an active margin to the west, passive margins to the east and north, and numerous fjords and estuaries, the seafloor of Canada is prone to subaqueous landslides. The Geological Survey of Canada (GSC) facilitates government response in times of crisis by providing timely and concise information to Canadians, and informs the strategies to address natural hazards. Thus, the GSC is conducting a national assessment of the subaqueous landslide hazard. This paper reviews dozens of major subaqueous mass movement deposits with an emphasis on recent publications and summarizes the attempt to produce a national database. The types range from ephemeral turbidity current deposits to very large deposits (>100 km 3 ). To date, 1266 deposits are identified with many more expected as mapping progresses. This work is important as it will feed into the larger national tsunami strategy, and is a step forward for the national government to manage the risk. Canada is among the first countries to enter its entire database using the consistent morphometric characterization recommended by members of the UNESCO IGCP-640 (S4SLIDE) Community.

Abstract Turbidity currents transport globally significant volumes of sediment and organic carbon into the deep-sea and pose a hazard to critical infrastructure. Despite advances in technology, their powerful nature often damages expensive instruments placed in their path. These challenges mean that turbidity currents have only been measured in a few locations worldwide, in relatively shallow water depths (<<2 km). Here, we share lessons from recent field deployments about how to design the platforms on which instruments are deployed. First, we show how monitoring platforms have been affected by turbidity currents including instability, displacement, tumbling and damage. Second, we relate these issues to specifics of the platform design, such as exposure of large surface area instruments within a flow and inadequate anchoring or seafloor support. Third, we provide recommended modifications to improve design by simplifying mooring configurations, minimizing surface area and enhancing seafloor stability. Finally, we highlight novel multi-point moorings that avoid interaction between the instruments and the flow, and flow-resilient seafloor platforms with innovative engineering design features, such as feet and ballast that can be ejected. Our experience will provide guidance for future deployments, so that more detailed insights can be provided into turbidity current behaviour, in a wider range of settings.

Abstract This volume, prepared for the 126th GSA Annual Meeting in Vancouver, Canada, offers guides to trips in the Cascadia subduction zone. The active tectonism of the region has had a profound effect on the bedrock and surficial geology of the area, and on human interactions with the geologic environment. These themes are reflected in the trips associated with the meeting. Trip topics relate to bedrock geology, volcanism and Cordilleran glaciation and deglaciation, as well as human interaction with the natural environment. The trips that discuss human interaction cover archaeology, natural hazards and the urban environment, as well as the role that local geology and tectonism have played in shaping colonization of the region since the last glaciation. The field guide volume has something for everyone!

Abstract This one-day field trip through Metro Vancouver, British Columbia, illustrates the breadth of societal contributions afforded by urban geology. In addition to the classic geotechnical needs and concerns about geological hazard mitigation, interest is growing in the heritage and educational values of geological sites, and their potential roles in fostering a sense of place. As urban populations become increasingly diverse, they cannot be united by shared history; therefore, the shared environment can emerge as a strong element of shared identity. With more than 50% of the global population now living in urban centers, it becomes too easy for them to become alienated from geology as a “science of the hinterland,” devoted more to resource exploration and development than to matters of shared heritage. A surprising amount of geological information can be studied and appreciated in an urban area, despite development. There is a need for ongoing urban geological surveys, supported by educational institutions linked to urban administrations and provincial and/or state and national agencies. The surveys would have rapid-response capability to allow optimal recovery of fine-scale information from the temporary exposures that daily come to light. Metro Vancouver’s exposed (in-place) bedrock and surficial deposits represent over 100 million years of Earth history. It is a history of continuous mountain building and collapse as recorded by granitic batholiths with cross-cutting dikes and sills, Mesozoic and Cenozoic clastic sedimentary rocks, volcanic features, and Quaternary glacial and nonglacial deposits. Several of its landforms have cultural significance for both aboriginal and settler populations, reflected in their names and associated stories. Both information and meanings reside in the urban geological landscape and beg to be interpreted, providing excellent educational and research opportunities even as they also contribute to cultural continuity.

Abstract The natural landscape of the North Shore of Vancouver is a mountainous one extending from sea level to ~1400 m. Land below ~400 m has been undergoing increasing urbanization since the 1950s. Development has encroached on areas subject to natural hazards such as floods, debris flows, slope failures, and coastal inundation. We will visit examples of these urban hazards, discuss problems of hazard identification in a forested landscape, and review urban planning and engineering responses to hazard management.