Am improved source mechanism for the 1935 Timiskaming, Quebec earthquake from regional waveforms

Bent, Allison L.

doi:10.1007/bf00876667

Cited by 35 publications

(38 citation statements)

References 17 publications

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“…The resulting mechanisms are not identical, but both indicate thrust faulting on a plane striking roughly northwest, which is typical of earthquakes in this region (for example, Wahlstr/Sm, 1987; Adams et al, 1988Adams et al, , 1989Adams, 1991;Lamontagne et al, 1994;Bent, 1996).…”

Section: Focal Mechanismmentioning

confidence: 95%

The Kipawa, Quebec "Millennium" Earthquake

Bent

Lamontagne

Adams

et al. 2002

Seismological Research Letters

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The Kipawa, Qudbec earthquake (raN5.20TT; rob4.5 plDC) occurred on 1 January 2000 at 11:22:57UT (6:22 EST). The epicenter (46.88~ 78.92~ was beneath Lake Kipawa, approximately 10 km north of the town of Tdmiscaming, Qudbec. The earthquake was felt to distances exceeding 500 km. The "Felt Earthquake" form on the Geological Survey of Canada's Web pages received more than 450 submissions from more than 170 communities regarding this earthquake. The shaking was very strong for residents within 50 km of the epicenter (maximum intensity MM VI), and minor damage (fallen light objects, one broken ventilation pipe, and cracks in plaster) was reported. The seismograph station EEO (Eldee, Ontario), at a distance of 29 km, recorded a 0.023 g peak vertical acceleration, and a digital strong-motion unit operated by Hydro-Quebec at 68 km distance recorded 0.014 g maximum horizontal acceleration. Twenty-three aftershocks were recorded, ranging from M L 1.1 to raN2.2. To supplement station EEO, two portable recorders and a digital strong-motion instrument were installed on 2 January 2000 at distances of 9 to 22 km from the epicenter of the main shock. Preliminary analysis of the main shock from P first motions and surface-wave modeling indicates thrust faulting on an east-west or northwest-southeast trending plane. A depth of 13-16 km is indicated by the regional and teleseismic body waves. The epicenter is within 15 km of that of the magnitude (Mvr 6.1, 1935 Timiskaming earthquake and lies in a cluster of 76 earthquakes located since 1935. The area averages one magnitude 3 or greater earthquake every two years. There is an indication of a northwest-southeast elongation (parallel to the major faults of the Lake Timiskaming Graben), and focal mechanisms consistently show a northeast-dipping northwest-trending plane, which would be consistent with a fault outcropping under the Ottawa River and Lake Timiskaming.

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Section: Focal Mechanismmentioning

confidence: 95%

The Kipawa, Quebec "Millennium" Earthquake

Bent

Lamontagne

Adams

et al. 2002

Seismological Research Letters

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“…It is possible that the large range of focal depths indicates that these areas have experienced larger earthquakes in the geologically recent past, with modern seismicity representing ongoing stress readjustments. For example, larger (M Ͼ6) earthquakes are known to have occurred in the Timiskaming region (M 6.2 in 1935;Bent, 1996), whereas paleoseismic evidence suggests Ottawa may also have experienced large earthquakes within the past few thousand years (Aylesworth et al, 2000). We speculate that a wide distribution of focal depths may serve as a useful contemporary marker of locations where large events have occurred in the recent geologic past.…”

Section: Focal Depth Distribution Of Studied Earthquakesmentioning

confidence: 97%

Focal Depths for Small to Moderate Earthquakes (mN >=2.8) in Western Quebec, Southern Ontario, and Northern New York

Atkinson

2006

Bulletin of the Seismological Society of America

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Regional depth phase modeling is a useful technique to constrain earthquake focal depths for events within sparse networks. We demonstrate how regional depth phases can be used to obtain focal depths for hundreds of earthquakes with m N Ն2.8 that occurred from 1980 to 2004 in southern Ontario, western Quebec, and northern New York State. We discuss the development of regional depth phases with distance, their use in focal depth determinations by matching waveforms to synthetics, and possible sources of error. In general, focal depths can be determined to within about 3 km when there is at least one record at regional distances with clearly identifiable depth phases such as sPmP or sPg.In southwestern Ontario and northern New York, focal depths range from 2 to 15 km. In areas of western Quebec and along the Ottawa River valley in Ontario, focal depths range from 2 to 25 km. More than half of the earthquakes in a cluster of activity near Maniwaki in western Quebec are deeper than 20 km. All earthquakes deeper than 20 km occurred north of about 45.3Њ N.There is an intriguing tendency for earthquake depths to cluster near 8 km, 12 km, 15 km, and 22 km. Another interesting observation is that there are several earthquake pairs or small groups with very similar epicenters but quite different depths. The most active regions, in western Quebec and along the Ottawa River valley, tend to exhibit a relatively wide range of focal depths along broad zones that trend roughly northwest, suggesting that seismicity is occurring along diffuse northwest-trending faults throughout the crust. The wide range of focal depths may indicate the potential for a larger maximum scale of fault rupture and serve as a contemporary marker of locations where large events have occurred in the recent geologic past.

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“…The last was one of Canada's most damaging earthquakes with extensive impacts on urban infrastructure (Bent, 1996a). The epicenter of the 1935 Timiskaming Earthquake (the third largest on record in eastern Canada) is located 10 km east of Lake Timiskaming on the western margin of Lake Kipawa and was felt over some 1.3 million m 2 of eastern North America (Hodgson, 1936a, b;Bent, 1996b). Eight aftershocks of magnitude 4 to 5 occurred until March 1936.…”

Section: Western Quebec Seismic Zonementioning

confidence: 98%

“…Part of Lake Kipawa was briefly surveyed by Shilts (1984) who identified slumps from the 1935 event. The principal objective of our study was to systematically map the geographic extent of landslides in Lake Kipawa with reference to the recently constrained epicenter of the 1935 earthquake that is now placed along the western margin of the lake (Bent, 1996b) (Fig. 2).…”

Section: Western Quebec Seismic Zonementioning

confidence: 99%