A significant earthquake has shaken an area of eastern Canada, serving as a reminder of the region's potential for seismic instability.
Wednesday's magnitude 3.9 temblor struck shortly after midnight, local time, with an epicenter near Beloeil, about 20 miles northeast of Montreal, Quebec, the USGS Earthquake Hazards website showed.
The shallow quake had a focal depth of 6 miles.
Epicenter for magnitude 3.9 earthquake near Montreal, Quebec, on Oct. 10, 2012 (USGS Earthquake Hazards Program).
Natural Resources Canada, meanwhile, pegged the quake magnitude at 4.5.
There were no immediate reports of injury or damage, the CBC News website said.
Even so, the shaking caused a bit of a stir. Calls to 911 spiked, and some people even left their homes briefly, the CBC said.
Buildings rumbled during that quake, lasting about 10 seconds.
The quake was felt in southern Quebec, easternmost Ontario and nearby border areas of the U.S., respondents to the USGS website reported. A few Ottawa residents felt the quake, according to the CBC.
Widespread perception is that eastern North America, both in the U.S. and Canada, is relatively stable and free of earthquakes. After all, eastern North America has no known active plate boundaries, unlike the notorious "Ring of Fire" seismic belts bordering the Pacific Ocean.
However, seismic records show that earthquakes are not at all uncharacteristic of the area.
A quake hits the area, mostly unfelt, about once every five days, CBC meteorologist -- and seismologist -- Johanna Wagstaffe said.
This latest temblor happened near the eastern edge of what the USGS calls the "Western Quebec Seismic Zone." Historic earthquakes have been felt here for three centuries, and at least two were damaging.
Outline of the Western Quebec Seismic Zone (USGS).
The first of two historic damaging quakes within this seismic zone happened in 1732 and was of magnitude 6.2, according to the USGS.
Then, in 1935, a magnitude 6.1 earthquake rocked the Montreal area, where significant damage resulted.
A number of faults have been traced and mapped in this seismic zone. It is likely that many more remain undetected, the USGS said.
There are a number of known seismic areas in eastern North America, one of which is found north and east of the city of Quebec.
Others known to have yielded damaging earthquakes are found in the Boston area and in South Carolina.
The Central Virginia Seismic Zone sparked a damaging magnitude 5.8 earthquake that was felt in much of the mid-Atlantic states on Aug. 23, 2011.
The plum rains are known as "meiyu" in China, the "baiyu" or "tsuyu" in Japan, and the "jangma" in the Koreas. The heart of the plum rain season stretches from early June to mid-July, with a tendency to shift south to north across the affected area.
In the wake of the mid-June cloudbursts, most of Pakistan to northwestern India last week saw a return to dry, hot weather typical of the weeks leading up to the Monsoon onset. It was as if the Monsoon withdrew to its "normal" position for the latter half of June.
The 38.5 degree C (101 degrees F) reading Tuesday in Ajaccio, Corsica, may have been tops in Europe.
Monsoon Onset was June 13th, 2013, in Delhi, almost two weeks earlier than average. The June 15th onset at Karachi and Islamabad was more like three week ahead of schedule.
In Pakistan, hit-or-miss downpours missed the Sindh capital, Karachi. One did hit Pad Idan, where it left 60 mm of rain Wednesday. This was more than 20 times greater than the normal June rainfall.
It is still possible that this scenario is over wrought as to the intensity and spread of rain in Pakistan and northwestern India. However, it is the hunch of the present forecaster that some very unusual weather is going to unfold in the Subcontinent during the next week!