Christchurch suburb rocked by drain explosions

The Fire Service near a Christchurch drain after reports of an explosion. Photo / Christchurch Star

An electrical fault is to blame for a series of explosions that shot black smoke and flames into the air in Christchurch today.

Witnesses said about five explosions occurred in drains on the corner of Straven Rd and Riccarton Rd after midday.

Adam Hogan was in an internet cafe when he heard a loud bang outside.

"It was like a big earthquake,'' he said.

"There was definitely some force behind it.''

Mr Hogan said he walked outside and saw black smoke and flames coming out of a vent in the ground.

"If you were walking past it'd take your head off, it was all channelled to that drain. It just went boom.''

He said the smoke shot "as high as a tree'' but wasn't dense, dying down and pouring out of the drain.

"It wasn't scary it was just interesting, I've never seen anything like that before.''

Another internet cafe patron, Tracy Shaw, said: "It took the power out and you could feel a surge in the floor, it actually felt like the floor was moving.''

He said the power had gone out five times during the explosions.

An Orion spokeswoman said the power company was called to the site about 3.15pm and discovered a low voltage underground cable fault.

This type of fault was not uncommon, she said, with Orion seeing "a few a week''.

"We need to dig up the ground where the cable is and it is quite a reasonable repair job. It can take up to 12 hours.''

The spokeswoman said power would not be off in the area for all of that time, as Orion was usually able to re-route power.

She said the Orion representative had yet to start repairs as they had been at the scene for only half an hour and were still assessing the fault.

Sockburn Fire Station senior officer John Baxter said earlier the fire brigade did not know what had caused the explosions.

Earlier this afternoon fire communications shift supervisor Andrew Norris said Orion, City Care drainage services, and gas and engineering experts were on site with the fire services looking into all possible causes.

Mr Norris said it could have been an issue with a gas main or main power cable.