Discussion of "Analysis and reinterpretation of deformation features in the Rouge River valley, Scarborough, Ontario"

Abstract

Structurally deformed Pleistocene sediments along the Rouge River are located < 7 km from Pickering Nuclear Generating Station (PNGS). They rest on structurally disturbed Paleozoic sedimentary strata and lie within an area of poorly understood geophysical and structural complexity in the underlying Proterozoic basement (Wallach et al. 1998). PNGS was constructed adjacent to a major population centre (now more than five million people) in the late 1960s largely in ignorance of local and regional geological conditions and well before the plate tectonic paradigm provided a model for basement evolution. The presence and significance of major bedrock lineaments, such as the Central Metasedimentary Belt Boundary Zone (CMBBZ) that passes directly under PNGS, together with several other structures that intersect below Pickering, was not then known. Today, such structures are recognised as being defined by persistent earthquake activity (Mohajer 1991, 1993, 1995; Wallach et al. 1998). A magnitude 3.1 earthquake occurred within 3 km of PNGS on May 24, 2000. Ten smaller magnitude earthquakes have been recorded in the last decade along the structure between Niagara and Pickering by the seismic networks of the Geological Survey of Canada and the United States Geological Survey. The more recently constructed Perry nuclear plant in the U.S.A. was temporarily closed in 1986 by a magnitude 5 temblor along the same CMBBZ structure. The local community has every right to be concerned about the presence of an aging nuclear reactor in their midst. The four Pickering “A” reactors were shutdown in 1997 as a result of “long standing management, process and equipment problems” (NPAG, Nuclear Performance Advisory Group 1997). As part of the recent Environmental Assessment regarding …