CGRG Bibliography of Canadian Geomorphology
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Author : Dineva S.; Mereu R.; and Eaton D.
Date : 2002.
Title : Fluid moderated seismicity in Great Lakes?
Publication : Seismological Society of America 2002, Annual Meeting 17-19 April 2002. Victoria Conference Centre, Victoria, British Columbia
Issue :
Page(s) :
Abstract
The Southern Ontario Seismic Network (SOSN) was deployed in 1991. The aim of this work is to determine precise locations for the events recorded by this network in the region of Lakes Ontario and Erie (Lat. 40.0°-44.5°N and Long. 82.0°-77.5°W), in order to delineate possible patterns of seismicity, to compare the modern seismicity with the historical one and determine if there is a correlation with the local geophysical fields. During the past 10 years over a hundred local events (M = 1.0 - 5.4) were recorded and were used in the study. The locations of these events have been calculated using data for the arrival times of P- and S- waves (bulletins of GSC, UWO and NEIC). Many of the phases were re-picked from original records. The estimated new location errors are in order of 1.6 km, based on the mean discrepancies from an independent analysis by two of us using different software packages. One is the modified version of the program HYPOCENTER (Lienert and Havskov, 1995), The seismic epicenters around the western part of Lake Ontario appear to be aligned to two distinct small bands that trend in a NE-SW direction. The positions and direction of these bands coincide very well with the borders of a positive magnetic anomaly in western Lake Ontario. This seismicity appears to be controlled by known SE dipping Pre-Cambrian structures that have the same orientation as the linear earthquake bands. Even though the structures are more extensive almost all of the events are confined to the area of the Lakes Ontario and Erie or adjacent areas to the southeast. There are almost no events in land areas north of the Lake Ontario. This pattern leads us to speculate that the faults along these structures may be being reactivated by water from the lakes. The mechanism may be related to pore pressure variations similar to that found in reservoir induced seismicity studies.
Bibliography of Canadian Geomorphology