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Two Days, Three Earthquakes, Three Provinces

Description: 

More than a dozen earthquakes are recorded daily in Canada. Widely felt earthquakes attracting media attention are less frequent. The occurrence of three such earthquakes in three distinct regions of the country in less than thirty-six hours is unusual. The action began with a magnitude (MW) 4.7 earthquake near Grand Prairie, Alberta at 15:41 UT on 20 February 2025 in a region of known wastewater injection and previous industry induced events. In the weeks preceding this event there were several small, both suspected and confirmed, industry induced events in the epicentral area and neighboring British Columbia (BC). As of 25 February, it has not been confirmed whether this event was induced. It was felt up to 200 km away in Edmonton and Prince George; reports indicate weak-to-light shaking near the epicenter. Due to the potential links to hydraulic fracturing, there was broad interest in the event. Thirty hours later, a magnitude (Mw) 4.7 earthquake occurred 75 km north of Vancouver, near Sechelt, BC, at 13:27 local time (21:26 UT 21 February). More than 7000 people submitted felt reports via the Natural Resources Canada “Did You Feel It” page, making this the most reported event in our database. Interest was high as this event resulted in the first Earthquake Early Warning (EEW) alert in southwestern BC. Vancouver City Hall was evacuated, and one BC Ferries terminal was closed for a short time. The EEW system functioned properly but there was considerable misunderstanding among the public as to who should have received the alert. More than 50 media interviews have been conducted, many explaining EEW, how the public should expect to be alerted and how they should respond. This was a valuable test for the EEW system and public education in the region. Finally, a small (MW 2.5) earthquake occurred near Chatham, Ontario, at 22:40 UT on 21 February. Although small, the event attracted media attention because it occurred in a populated region where felt earthquakes are rare. Its occurrence shortly after the Sechelt earthquake meant that staff were temporarily responding to both earthquakes simultaneously.

Session: Late-breaking on Recent and Future Large Earthquakes - I

Type: Oral

Date: 4/15/2025

Presentation Time: 11:30 AM (local time)

Presenting Author: Allison

Student Presenter: No

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