SOLVED
A FRIEND SUGGESTED WATER-PIPE DAMAGE, BINGO - JUST YESTERDAY A HOSEPIPE OF OURS WAS DIRECTED AT THAT PATCH - SORRY FOR BOTHERING YOU GUYS!
any of you wiser guys have a clue as to what could have caused this? although my yard is surrounded by inter alia walls this could be a mole? this happened yesterday and all efforts to interest our cat in investigating at least the smell have been in vain…
