"Mum, it's coming in the house!" her 19-year-old daughter Tessa cried.
Ms Mawhinney, a 49-year-old primary school executive officer, knew it would return with the shaking. It always did.
The liquefaction sludge was bubbling through the skirting boards in Tessa's bedroom, as well as in the bathroom and toilet.
Today, as she surveyed the mess, Ms Mawhinney described the latest blow to her already written-off house as a "kick in the guts".
Liquefaction damage to the newly finished road outside Diane Mawhinney's house. Photo / Mark Mitchell "After all this time, you think it's all over ... It's very demoralising," she said.
"You wonder if you should make another claim with EQC or not."
The house was badly damaged in the February 22, 2011, killer quake.
It was damaged again and flooded in the June 2011 tremor.
The December 23 magnitude-6 jolt that year saw further sinkholes appear and even worse liquefaction silt.
Ms Mawhinney is still negotiating a settlement with insurers Southern Response.
The latest quake is a psychological blow, she says.
"I'm not that worried about the house -- it's a write-off already. I'm more upset for the street.
"It's a lovely street, with great neighbours, and we're close to the beach and the forest. I want to stay here, but I do wonder now.
"I really miss just being able to go to the garden centre and buy some plants. It's a simple pleasure, but I can't do it. Life is always just on hold."