| Title | The 2015 Canada Day, Mw 3.8, earthquake in Nova Scotia |
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| Author | Bent, A L; Peci, V; Halchuk, S |
| Source | Seismological Research Letters vol. 87, no. 5, 2016 p. 1224-1231, https://doi.org/10.1785/0220160074 |
| Image |  |
| Year | 2016 |
| Alt Series | Earth Sciences Sector, Contribution Series 20160009 |
| Publisher | Seismological Society of America (SSA) |
| Document | serial |
| Lang. | English |
| Media | paper; on-line; digital |
| File format | pdf; html |
| Province | Nova Scotia; Eastern offshore region; New Brunswick |
| NTS | 20O/01; 20O/02; 20O/07; 20O/08; 20O/09; 20O/10; 20O/15; 20O/16; 20P; 21A; 21B/01; 21B/02; 21B/07; 21B/08; 21B/09; 21B/10; 21B/15; 21B/16 |
| Area | Bay of Fundy; Yarmouth; Shelburne; Liverpool; Digby; Atlantic Ocean |
| Lat/Long WENS | -67.5000 -64.0000 45.0000 43.0000 |
| Subjects | geophysics; structural geology; seismology; earthquakes; earthquake foci; structural features; faults, thrust; earthquake mechanisms; modelling; seismic waves; p waves; synthetic seismograms |
| Illustrations | location maps; tables; sketch maps; seismograms; focal mechanisms |
| Program | Canadian Hazard Information Service |
| Released | 2016 08 10 |
| Abstract | On 1 July 2015, a magnitude (MN, Mw) 3.8 earthquake occurred north of Yarmouth in southwestern Nova Scotia, a region of extremely low seismicity. Prior to this event, only five earthquakes had been
recorded within 50 km of its epicenter since 2000. The earthquake caused no damage but was widely felt in southwestern Nova Scotia with nearly 600 people filling out the Geological Survey of Canada's online "Did You Feel It?" form. Good-quality
regional seismograms enabled us to determine the source parameters of the earthquake. The focal mechanism determined by a regional centroid moment tensor inversion is indicative of oblique-thrust faulting. We believe this to be the first focal
mechanism solution for a Nova Scotian earthquake. It is consistent with those of earthquakes in the neighboring regions of New Brunswick and Maine and with the regional stress field. Depths were obtained by the moment tensor inversion and by regional
depth phase modeling, with consistent results indicative of a focal depth of 9-10 km. The Mw 3.8 is larger than average based on the MN value but within the range of previous observations for eastern Canada. A magnitude (MN) 2.2 aftershock occurred
?7 min after the mainshock but was not reported as felt. A focal depth of 8 km was obtained via the regional depth phase method. The focal mechanism of the aftershock was not determined directly, but a comparison of the waveforms to those of the
mainshock suggests a similar source. |
| Summary | (Plain Language Summary, not published)
While small, the magnitude 3.8 earthquake that occurred on Canada Day (1 July) 2015 is of scientific interest because it occurred in a region of
extremely low seismic activity. The earthquake was well recorded by the Canadian National Seismograph Network, allowing us to determine its depth, focal mechanism and moment magnitude. While we have no previous focal mechanisms for Nova Scotian
earthquakes, the oblique thrust mechanism is similar to earthquakes in New Brunswick, Maine and offshore. Nearly 600 people filled out an online "Did You Feel It" survey, which provides information about the felt effects of the earthquake and a
reference for calibrating historical earthquakes. |
| GEOSCAN ID | 297901 |
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