A magnitude 5 aftershock was nothing to the shock Jennifer Graham got when she returned home on Tuesday.

She walked into the bathroom to wash her hands - and found an envelope containing $3000 behind the basin taps, The Press reported.

She thought that there had been a break-in but then quickly realised burglars don't leave presents.

The mystery was solved when police tracked down the house's former owner, who said he hid the money in the house before he moved out five years ago.

He told police that he was in the habit of stashing cash around the place, up to about $3000 at a time.

Ms Graham thought the money had been hidden behind the bathroom mirror, and the envelope dislodged by the aftershock.

The money was returned to the man who thanked Ms Graham.