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TitleThe 17 May 2013 M 4.6 Ladysmith, Quebec Earthquake
AuthorBent, A L; Lamontagne, MORCID logo; Peci, V; Halchuk, S; Brooks, GORCID logo; Motazedian, D; Hunter, J; Adams, JORCID logo; Woodgold, C; Drysdale, J; Hayek, S; Edwards, W
SourceSeismological Research Letters no. 86, 2015 p. 1-17,
Alt SeriesEarth Sciences Sector, Contribution Series 20140131
PublisherSeismological Society of America (SSA)
Mediapaper; on-line; digital
File formatpdf
NTS31F/07; 31F/08; 31F/09; 31F/10; 31F/15; 31F/16; 31G/05; 31G/12; 31G/13; 31J/04; 31J/05; 31K/01; 31K/02; 31K/07; 31K/08
Lat/Long WENS -77.0000 -75.5000 46.5000 45.2500
Subjectstectonics; geophysics; earthquakes; seismic data; faulting; epicentres; earthquake damage; earthquake magnitudes; earthquake mechanisms; earthquake studies
Illustrationsdigital elevation models; location maps; seismograms; stereonets; graphs; tables; photographs; plots
ProgramCanadian Hazard Information Service
Released2015 01 28
AbstractAlthough moderate in size (MN 5.2, M 4.6), the earthquake that occurred near Ladysmith, Quebec, on 17 May 2013 was one of the best-recorded earthquakes to have occurred in eastern Canada in recent years due to the fortuitous deployment of U.S. Transportable Array stations in a region that was already well covered by the Canadian National Seismograph Network. This data set allowed us to study the earthquake and its aftershocks in better detail than we could have done in the past. Moment tensor and first-motion focal mechanisms suggest that it was a typical western Quebec earthquake resulting from thrust faulting on a northweststriking plane. Several methods were used to determine the depth, all indicating a depth of 12-15 km. The aftershock sequence, which included a magnitude 4.1 (MN) earthquake occurring 10 min after the mainshock, was relatively rich in MN >3:0 events and contrasts sharply with that of the 2010 Val-des-Bois earthquake (also in western Quebec). Strongmotion data from the Ladysmith earthquake contributed to an ongoing study to model soft soil amplification and basin effects. The earthquake was felt to distances in excess of 500 km, and more than 4300 people filled out an online "Did You Feel It?" survey, providing a detailed picture of macroseismic effects. Visits to Ladysmith and nearby communities found evidence for minor damage confined to the epicentral area. It is difficult to correlate the Ladysmith sequence with any known faults in the region, but it is noted that some local-scale lineaments in the epicentral area trend subparallel to the nodal planes of the focal mechanism.
Summary(Plain Language Summary, not published)
This paper summarizes the properties of the Mw 4.6 Ladysmith, QC earthquake that occurred on 17 May 2013. The earthquake was felt throughout the Ottawa-Montreal region. It was extremely well recorded instrumentally due to reasonably dense coverage by the national network combined with the deployment of the US Transportable Array in the region. This allowed many techniques to be applied to the data set. It appears to be a typical western Quebec earthquake caused by thrust faulting at mid-crustal depths. The fault plane orientation is consistent with local lineaments but the earthquake cannot be associated with a specific fault. Strong motion data from this earthquake contributed to an ongoing study of basin and soft soil effects. Damage was minor and confined to the epicentral region. The aftershock sequence was anomalous in that there was a relatively high ratio of large to small aftershocks, the largest of which was a magnitude (mN) event that occurred 10 minutes after the mainshock.

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