Linking earthquake seismicity to underlying fault structure from studies of simple models

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Large earthquakes, as a natural disaster, represent an almost incomprehensible and incalculable risk to today’s urban populations in both eastern and western Canada. However, earthquake losses can be reduced through better knowledge of earthquake hazard, a prerequisite for preparation and mitigation. The goal of my research program is to provide a comprehensive understanding of the processes which govern natural and anthropogenic hazards and, in particular, those which generate earthquakes, and thus improve the associated estimates of regional seismic hazard. The long-term objective of this proposal is to link the underlying physical characteristics of an earthquake fault to the spatial and temporal patterns observed in natural seismicity, particularly those that govern the magnitude, location and recurrence. The short-term objectives are to provide quantitative measures of the effect of damage and fault mechanics on the spatial and temporal clustering in natural earthquakes and to define the relationship between fault surface properties, such as stress distribution or friction coefficient, and the associated seismic and geodetic time histories. Studies suggest that larger, stronger asperities produce bigger events and are associated with increased seismic hazard. Here, studies of the magnitude-frequency relation, foreshock-aftershock duration, and interevent time from natural and synthetic time series will provide invaluable insights into the mechanics of the fault surface from computer simulations of both simple faults and fault networks. This research program will, for the first time, extend this research to natural earthquake faults using historical seismic records. The primary question to be addressed here is: What is the relationship between the statistics of earthquake seismicity – a phenomenon that is easily and accurately measured today – and the fault parameters that control the magnitude, location and time-of-occurrence of the largest events? New outcomes include a better understanding of the physical process preceding the occurrence of large earthquakes through improved quantification of the physical factors that affect their short- and long-term behavior. The ability to quantify the precursory dynamics for large earthquakes is fundamental to our ability to assess both the magnitude and likelihood of future events, allowing us to significantly improve their predictability and more accurately assess the time-dependent seismic hazard.