But on that fateful Friday, when the North American plate slid over the Pacific plate along a subduction zone running 130km (80 miles) off the Pacific coast of northern Japan, the shock leapt from the first segment to a second and on to a third, extending the fault zone some 400km and increasing its intensity more than 30-fold.
You had merely to lead them to the plate-glass porch door and point out a squirrel or a cat running on the railing, or the automatic pool vacuum flipping its tail in the water as it carried on, side to side, end to end.