An earthquake is erupting but not on the A415

Woke up a little before 1 last night, absolutely convinced that the bed was shaking, and in the dark across the room I distinctly heard something fall over. Lay awake for a while.

No car alarms, no dogs barking, no sign of civil unrest or discord, no sound of anything else in the house falling over, Best Beloved still fast asleep. Decided I must have been imagining it - there was no earthquake.

Except that apparently there was.