Earthquake Rattles North America: Tens of Millions Affected".

A significant earthquake near the U.S.-Canada border rattled millions of people across several states and provinces on Tuesday. The tremor, occurring at 12:36 pm ET, was centered just 40 miles north of the city of Ottawa, Ontario. While the USGS reported a magnitude of 4.0, Earthquakes Canada measured the event at a slightly weaker 3.9.

The seismic waves spread across a 300-mile diameter, affecting many nearby populations. Residents in Montreal, home to 4.4 million people, felt the movement along with those in New York and Vermont. Although such quakes rarely cause major damage, the sudden movement caused widespread concern among the local population.

In Constance Bay, one resident described the initial sensation to CTV News as quite jarring. "The building was vibrating and it sounded like a large truck was going by at the beginning," they said. "It increased to where we felt the vibration in buildings." Another resident near Otter Lake, Quebec, shared the fear, stating, "The house was shaking and it scared us." No injuries have been reported following the tremor.

The epicenter lies within the Western Quebec Seismic Zone, a region of significant and ongoing geological risk. This area spans from Montreal to Temiscaming and includes the Laurentian Mountains and Eastern Ontario. Deep-seated pressure on ancient faults causes these cracks to slip and release sudden energy. This zone remains the primary seismic hazard for Ottawa, Gatineau, and many surrounding communities.

The National Capital Region has not seen a quake stronger than 5.6 since 1899. The last major event struck Cornwall, Ontario, and Massena, New York, in 1944. More recent tremors in 2010 and 2013 reached magnitudes of approximately 5.0.

This event follows a week of intense seismic activity across various parts of North America. On Sunday, an 18-earthquake swarm hit the Washington State coast, including a 4.2 magnitude event in the Pacific Ocean. Geologists fear the Cascadia Subduction Zone could be overdue for a massive earthquake exceeding magnitude 7.0. Additionally, a 5.7 magnitude quake struck Western Nevada on Monday, triggering several aftershocks in the area.