As it happened: Radio New Zealand's All Night Programme host Vicki McKay live on air as the earthquake struck.

Civil Defence has sought assurances that Radio New Zealand is working to fix issues which have left the station off air three times since New Year's Eve.

RNZ said power issues, caused by "ageing equipment" at the state broadcaster's Wellington headquarters, caused broadcast outages. It said steps had been taken to prevent further outages.

National Party broadcasting spokeswoman Melissa Lee said the outages were "hugely concerning" and raised "serious questions" about RNZ's contingency planning. She said the public broadcaster would face questions over the outages when it appeared at Select Committee and she may ask for it to prepare a briefing about the outages.

SUPPLIED RNZ has set up a "shadow" team in Auckland, to step in if power fails in Wellington.

"There are a lot of New Zealanders who rely on RNZ for information. It would have been a disaster if there was an emergency during those [outages]," she said.

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Pro-RNZ lobbyists and station insiders blamed tech woes on a funding freeze which they said prevented the broadcaster from properly maintaining its equipment. But Lee said it was "mischievous" to blame National, as funding was boosted during its last budget in 2017.

"This is a contingency planning issue," she said. "You would hope a national broadcaster has contingencies."

As a designated lifeline utility under the Civil Defence Act, RNZ has a responsibility to stay on air and update New Zealanders in the event of an emergency.

ROBERT KITCHIN/STUFF National Party broadcasting spokeswoman Melissa Lee has "serious questions" for RNZ.

RNZ communications manager John Barr said steps have been taken to prevent another outage. An Auckland "shadow" team, an emergency generator and other measures were now in place, he said.

Although the station did broadcast "dead air" during power failures twice on New Year's Eve and on Monday, Barr said the broadcaster would have been faster to react if there was an emergency.

He said "a major systems outage" struck RNZ's Wellington studios on three separate occasions, causing both RNZ National and Concert to go off air. The systems outages struck on the morning and afternoon of New Year's Eve and lasted for an extended period on Monday night.

During those times, RNZ National struggled to stay on air and at times, the station went dead. At its worst, Barr said RNZ National may have been dead for up to half an hour on Monday night.

"Back-up power units failed resulting in dead air. Technicians worked to restore transmission and broadcasts were switched to Auckland after a delay," Barr said.

KEVIN STENT/STUFF Radio New Zealand has faced power issues at its Wellington office.

He said technicians have found and "isolated" the faulty equipment and a new emergency generator had been brought to RNZ's Wellington office.

"We are confident that we can maintain services while replacing the faulty gear," he said. "The issues have been the result of a failure in aging equipment."

A "shadow" team was also established in Auckland, he said, to take over daytime programming if Wellington-based hosts go off air.

The overnight programme would also be moved to Auckland, until Wellington's equipment was fully restored, he said.

RNZ chief executive Paul Thompson has been moving staff to Auckland for some time. He said he hoped to have two offices, about equal in size, capable of keeping RNZ going if an emergency took out one of its sites.

AMBER-LEIGH WOOLF/STUFF Broadcasting and Civil Defence Minister Kris Faafoi.

Myles Thomas, the director of lobby group Better Public Media, said the outages were a major concern but not surprising.

"RNZ had been on frozen funds for so long, they no doubt have been unable to invest in or keep up with technology," he said. "They cut their costs to the bone."

The public broadcaster endured an eight year funding freeze under the National Government.

The freeze came to an end in 2017, with an extra $2.84 million. The coalition government then boosted its funding further last year, giving it an extra $4.5 million.

KEVIN STENT/STUFF RNZ chief executive Paul Thompson has been relocating staff to Auckland.

"Clearly, they need more funding. It's a really important service RNZ provides for all New Zealanders. For its broadcasts to stop, that's so basic. Their basic, core role is radio and they clearly need investment in that area," Thomas said.

Civil Defence said people should expect some lines of communication to fail during emergencies. The ministry and RNZ were required to have a working plan to maintain consistent broadcast during emergencies, but Civil Defence also worked with state television channel TVNZ and private broadcasters such as MediaWorks.​

A spokeswoman for Civil Defence said the ministry had contacted RNZ about its recent outages, and was told the public broadcaster had "taken steps to resolve" the issues.

Broadcasting and Civil Defence Minister Kris Faafoi​ could not be reached for comment on Tuesday.