Someone reports getting alerts from locations well outside 2kms of their alert

[katska]

Someone reports (see email for exact details) they have an alert set up for an address in Thorneside QLD 4158, and they're receiving alerts in Chambers Flat 4133.

If I look at an address nearby that reported, I also see results for Chambers Flat shown as 2km away - when if I look at the distance between these two addresses in google maps is shown to be about 45 km away
What could be happening here? Has the location encoding gone wrong?