Neotectonic faulting in metropolitan Toronto: Implications for earthquake hazard assessment in the Lake Ontario region

Mohajer, A. A.; Eyles, Nicholas; Rogojina, C.

doi:10.1130/0091-7613(1992)020<1003:nfimti>2.3.co;2

Cited by 26 publications

(7 citation statements)

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“…2; Table 3) also suggest that the magnitudes of the σ 1 and σ 2 principal stresses were probably close during that period. The interchange in the positions of σ 1 and σ 2 during D 3 may be the result of long-term uplift of rocks, aided by extension due to regional compression associated with NE-trending σ 1 , as suggested for the recent normal faults in eastern Metro Toronto (Mohajer et al, 1992Wallach, 1994), and in southeastern Lake Ontario (Thomas et al, 1993). Adams et al (1993) and Godin et al (2002Godin et al ( , 2003 presented alternative interpretations and argued that these normal faults might have resulted from glaciotectonism.…”

Section: Origins Of Regional-scale Faultsmentioning

confidence: 92%

Evolution of faulting and paleo-stress field within the Ottawa graben, Canada

Rimando

Benn

2005

Journal of Geodynamics

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Section: Origins Of Regional-scale Faultsmentioning

confidence: 92%

Evolution of faulting and paleo-stress field within the Ottawa graben, Canada

Rimando

Benn

2005

Journal of Geodynamics

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“…However, they may be the result of simple uplift caused by, for example, glacio-isostatic rebound. Alternatively, as suggested for the normal faults in eastern Metropolitan Toronto by Mohajer et al (1992), they may be the expression of isostatic rebound aided by extension consequent upon the application of a,. The northern boundary of the extended St. Lawrence rift system parallels, and is rather close to, the Hamilton-Presqu-ile fault.…”

Section: Discussionmentioning

confidence: 99%

“…McFaII (1990) reported on outcrop-scale, strike-slip faulting which affects, and therefore postdates the emplacement of, a Jurassic-age dike near Picton, Ontario. Mohajer et al (1992) described east-west to west-northwest trending normal faults, which displace the contact between the bedrock and the overlying Quaternary sediments, in eastern Metropolitan Toronto. The origin and exact age of this faulting are not known but, from the stratigraphy of the unconsolidated sediments, the age is bracketed between 70,000 and 13,000 years BP.…”

Section: Introductionmentioning

confidence: 99%

Recent Deformation in the Bottom Sediments of Western and Southeastern Lake Ontario and its Association with Major Structures and Seismicity

Thomas¹,

Wallach²,

McMillan³

et al. 2007

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“…Additional information from Ontario Geological Survey (1991), Forsyth ef a/. (1987), Wallach and Mohajer (1990), Mohajer era/., (1992), and Thomas era/., (1993 Forsyth et al (1987), Wallach et Mohajer (1990), Mohajer et al, (1992), et Thomas et al, (1993). (Fig.…”

Section: Toronto-hamilton Seismic Zone (Thsz)mentioning

confidence: 99%

Seismicity and Seismotectonics of the Western Lake Ontario Region

Mohajer¹

2007

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ABSTRACTThe western Lake Ontario region, a traditionally perceived area of low seismic risk, is densely populated and is home to, among other critical facilities, the nuclear reactors of Pickering and Darlington. These and other characteristics of the region call for improved estimates of seismic hazard. Due to a lack of understanding of the causative geological sources and recurrence characteristics of the reported seismic activity, there is considerable uncertainty regarding estimated ground motion parameters, a fundamental component of seismic hazard assessments. To attempt to improve the definition of the seismic source zones and, consequently, seismic hazard assessments, the hypocentres of about 30 local earthquakes were recomputed. A new data compilation, based on the revised locations or those with the least travel-time residuals, shows that local microearthquakes (ML"3.5) generally occur along, or at the intersection of, prominent aeromagnetic or gravity anomalies. A notable seismicity trend extends in a northeast-southwest direction between Toronto and Hamilton, and is bounded by magnetic lineaments. A major geological structure, the Central Metasedimentary Belt Boundary Zone (CMBBZ), coincides with a strong aeromagnetic anomaly which extends to the northeast into the Western Québec Seismic Zone. This magnetic lineament also extends to the south, across Lake Ontario, to join the Akron (Ohio) magnetic boundary that was associated with several historical earthquakes and with a mb=4.9 earthquake in 1986. Most of the seismic events recorded instrumentally in the 20th century have occurred within a depth range of 5 to 20 km. This observation supports the correlation of local earthquakes with deep geophysical and geological features, suggesting contemporary reactivation of basement structures. This may imply that a more conservative deterministic hazard estimate is needed to verify the probabilistic approach currently used to assess seismic hazard in southern Ontario.

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Neotectonic faulting in metropolitan Toronto: Implications for earthquake hazard assessment in the Lake Ontario region

Cited by 26 publications

References 0 publications

Evolution of faulting and paleo-stress field within the Ottawa graben, Canada

Evolution of faulting and paleo-stress field within the Ottawa graben, Canada

Recent Deformation in the Bottom Sediments of Western and Southeastern Lake Ontario and its Association with Major Structures and Seismicity

Seismicity and Seismotectonics of the Western Lake Ontario Region

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