Officials from Japan to California issued warnings after an 8.8-magnitude quake off Russia’s coast. Hours later, there were no immediate reports of major damage, although some areas remained on alert.

"The scope of tsunami impact is like no other hazard on the planet. Great earthquakes can trigger tsunami surges that attack nearby coastlines within minutes but still pack a large enough punch to damage distant shores more than a day later.

The earthquake that struck off the coast of Russia late Tuesday registered 8.8 on the Richter scale and ensuing tsunami has raised concerns that the Pentagon could be caught unawares by a natural disaster in a region where thousands of U.