The Effects of Topographical and Geotechnical Characteristics of Sites on Seismic Movements Due to Natural and Human-Induced Earthquakes

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Earthquakes occur in most parts of Canada, and their impact can be greatly influenced by site effects. Site effects are modifications of seismic ground movement due to local topography and geological characteristics. They can be a major concern for many populated areas, because of the potential of these site effects to contribute in unexpected ways to the destabilization of urban infrastructure. It has often been observed that, after earthquakes, some buildings located on hills or in sedimentary basins suffer greater damage than would be expected from their distances to the epicenter. For example, during the magnitude 7.2 Vancouver Island Earthquake in 1946, most of the damaged chimneys in Port Alberni were in areas built on thick soft soils. Houses built on rock exhibited little damage. In addition to naturally occurring earthquakes, recent years have seen dramatic increases in human-induced earthquakes. Human-induced earthquakes are those caused by human activities like hydraulic fracturing in tight shale formations and impoundment of reservoirs. Human-induced earthquakes can be just as devastating as natural ones. Among the many examples in this regard, we can highlight the large magnitude 7.9 China’s Sichuan Province earthquake near Zipingpu Dam in 2008, killing 69,000 people and leaving another 18,000 missing. This earthquake resulted from the reservoir impoundment. Geotechnical hazards must be considered to ensure public safety. This means assessing the potential for injection-induced reactivation of geological faults and seismic events associated with industrial underground operations. However, it also requires study of local topographical and geological characteristics (site effects) to determine how they will affect the response of infrastructure to seismic movements. This research program will focus on the development of new numerical tools that can model the dynamic behavior of soils. There are many practical applications of this research, including studies of slope failures caused by natural- and human-induced earthquakes, providing information for seismic hazard and risk assessments, and seismic analyses of embankment dams. In addition, this work will help to improve our current poor understanding of human-induced earthquakes caused by industrial underground activities. The potential economic benefits for Canada are significant. It has been estimated that large earthquakes near major centers like Vancouver, could result in economic losses from earthquake-induced damages that are on the order of seventy billion dollars. During this research program, two PhD students and two MSc students will be trained under my direct supervision. Through my guidance, these graduate students will gain valuable experience in the areas of porous mechanics and numerical modeling in geotechnical engineering that will be a considerable asset to Canadian engineering companies.