TORONTO - As an unfolding nuclear catastrophe erupts half a world away, forgive Canadians -- particularly those who live near the country's nuclear power plants -- for asking pointed questions about whether a similar disaster could strike in their back yards.

Some possible perils -- that of an earthquake, for instance -- are credible threats to the fleet of Ontario nuclear generating stations that stand sentry over the Great Lakes. Experts say the facilities are equipped to withstand any temblor Mother Nature could muster in the area.

But what about a tsunami? After all, they don't call them the Great Lakes for nothing, right?

Relax, say seismologists.

"To have an earthquake big enough to produce a tsunami, you need faults hundreds, if not even thousands, of kilometres long -- lakes just aren't that big," said Allison Bent, an earthquake expert with Natural Resources Canada.

Indeed, while the plants are already well-protected by virtue of their design and a litany of safety variables, procedures and redundancies, they're in a part of Canada where there's next to no risk of an earthquake that would be big enough to spawn a damaging wave.

Earthquake risk is moderate in eastern Ontario, but it's negligible in the south, where the Darlington and Pickering generating stations sit just east of Toronto on the edge of Lake Ontario. The Bruce facility is further west, on Lake Huron, 200 kilometres north of Sarnia, still in the safety zone.

"They're not the absolute lowest zone in our hazard map, but it's the second lowest," Bent said.

"The only places that would be really lower would be northern Ontario or the Prairies. It's very low relative to the Ottawa-Montreal area, which in turn is quite low relative to Vancouver."

Ontario's stability comes from both its distance from tectonic plate boundaries as well as its position atop the Canadian Shield, she said. The province does feel the odd quake, but they're typically too tiny to get anyone's attention.

The largest temblor in provincial history took place on the Quebec border in 1935 and had a magnitude of 6, well short of the 9 registered in the Japan quake. A rare magnitude 5 rattled residents of the two provinces last June, causing moderate damage but no injuries.

Tsunamis typically can't be triggered by anything less than a 7, which is why they're not a significant component of safety contingency plans at the province's reactors, said Ontario Power Generation spokesman Ted Gruetzner.

"Speculating is good, but you have to deal with what is realistic," Gruetzner said. "Our plants are built to realistic standards that we would get on Lake Ontario."

Those standards -- enough to withstand a magnitude 7 temblor -- are met with buildings designed with extra-deep foundations, reinforced concrete, steel-lined walls that measure two metres thick, and mechanisms designed to prevent floors from cracking.

The province's made-in-Canada nuclear technology offers some additional protection. Canada's Candu reactors run on comparatively small amounts of natural uranium, rather than the enriched uranium in use in Japan. They're also easier to cool.

Officials have said the Japanese disaster likely won't have any repercussions in Canada, which means there is no need to stock up on the potassium iodide tablets that can help protect against high levels of radiation.

Gruetzner said the attitude of nuclear plant employees should set the benchmark for other concerned Canadians.

"All these guys and women who work inside the plants and are the ones who are there on the front line ... they're not worried about these plants," he said.

"I think people in the community should feel safe. We have a very strong design, (and) we live in a very safe area from natural disasters."