The quake that shortened the day

The Tohoku earthquake moved the main island of Japan about two and a half metres east and made the Earth spin very slightly faster.

Shifting that much mass shortened the day by something like 1.4 microseconds — computed, not measured, and revised down from a first estimate of 1.8 — which makes it one of the very few things that speeds the Earth up. The Moon's tides work relentlessly the other way, adding about 1.7 milliseconds a century, which is a thousand times more and never stops.