ABSTRACT: Neotectonics of the Eastern Great Lakes Basin cities: Will we experience a major earthquake?

CGRG Bibliography of Canadian Geomorphology
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Earthquake-engineering design of critical structures, such as major residential and office buildings, utility facilities, infrastructure, and lifelines, is a major concern for cities in the eastern Great Lakes basin (EGLB.) Several types of neotectonic studies have been done in the region around Lakes Erie and Ontario to determine whether earthquakes occur randomly on unknown small faults or are the result of stress release along regional tectonic structures. Earthquake-magnitude/fault-length relations from other parts of North America suggest that regional, seismically active, tectonic structures in the EGLB could produce large earthquakes. Modern earthquake maps show clusters of epicenters aligned on the St. Lawrence-Lake Ontario-Lake Erie lowlands linear topographic depression (SL-LO-LE) at its intersection with postulated or confirmed cross structures, such as the Clarendon-Linden fault system. Surface mapping of faults, pop-ups, and liquefaction features, along with geophysical mapping of steps and disruptions on buried bedrock surfaces in Lake Ontario, have convinced some researchers that these cross structures, and possibly the SL-LO-LE, are active fault systems capable of producing large earthquakes. Others argue, however, that the data can be related totally to non-tectonic processes, such as glacial ice-shove. The arguments for and against a high seismic risk in the eastern Great Lakes basin continue and will be aired in an upcoming special issue of Tectonophysics. No fault has been universally accepted by researchers of neotectonics as unequivocally active, even though extensive confirmed or hypothesized tectonic structures trend under EGLB cities and have been blamed for concentrating earthquakes. Consequently, seismic risk to critical structures is still undetermined; thus a cautious approach to engineering design is needed. We all know that earthquakes will continue, but we still ask where, when.

Bibliography of Canadian Geomorphology