The New Zealand Red Cross has set up a web page to help connect those affected by the volcano emergency, including many Australians.
One of three South Australians missing after the New Zealand eruption is alive and in hospital, authorities have confirmed.
Adelaide woman Lisa Dallow has been found alive in New Zealand following the Whakaari volcano eruption.
Her partner and daughter are still missing.
Ms Dallow, 48, along with her husband Gavin, 53, and 15-year-old daughter Zoe Hosking were reported missing after the disaster.
They had taken part in a day trip to White Island during a cruise.
Ms Dallow's employers, energy company Santos, said in a post to Facebook she is a “very well respected engineer, and a good friend to many throughout the business".
Before news of her fate, the family said in a statement there had been no word from the trio since the eruption.
"We feel for all the families who are going through the same frustration and fear for loved ones as we are," it said.
"Our thoughts also go out to the emergency workers who have done so much for the injured and ask that their safety is paramount."
Earlier, Mr Dallow's father Brian told the ABC his relatives "might be in hospital".
"We're not sure. We don't really know anything," he said.
A statement released by Zoe's school, St Aloysius College, also confirmed the family was unaccounted for.
"Information is scant at this time but SAC is now seeking to provide preliminary advice to the school community," the school said.
The three were on a tour of White Island with 21 other Australians when the active volcano erupted, spewing smoke, ash and debris thousands of metres into the air.
Three Australians are among six people confirmed dead following the volcanic explosion in New Zealand.
More Australians remain missing, while 13 are in hospital being treated for horrific burns and other injuries, the federal government said.
There are serious concerns for the Langford family of North Sydney with Anthony, 51, and Kristine, age unknown, and their children Jesse, 19, and Winona, 17, reported as missing.
They were on a cruise and decided to take a tour of the island at the time of the explosion.
"All we know is that they went on a cruise on White Island, there was an explosion and they're missing," Mr Langford's brother told Seven News.
The sister of a missing Brisbane woman and her adult daughter has also told the ABC of her rising concern.
Barbara Whitehead has told the broadcaster she's checked with seven New Zealand hospitals trying to find her sister Julie Richards, 47, and niece Jessica Richards, 20.
But there's been no word about the pair, despite other checks with New Zealand police, foreign affairs officials, and the pair's cruise company.
They'd been booked on a tour of the island from the Ovation of the Seas cruise ship, with the mother and her vet student daughter due to return home next weekend.
A website set up by the New Zealand Red Cross to help connect people affected by the catastrophic volcanic eruption listed almost 20 Australians missing.
People from multiple countries, including Australia, have been using the site to register their loved ones as missing via Restoring Family Links.
The multiple nationalities on the list show the scale of the panic the disaster has sparked since the eruption on Monday.
People were seeking information about loved ones from the UK, US, China, Singapore, France, Guatemala, Hong Kong, Canada, Portugal, Myanmar, New Delhi, New Guinea, and Holland.
AUSTRALIANS LISTED AS MISSING VIA RED CROSS
Australia (no state listed)
Susan Maree Cole, no age given
Martin Hollander, 48
Anthony Langford, 51, partner Kristine, son Jesse, 19, and daughter Winona Langford, 17, from North Sydney
Jane Murray, 56, Sydney
Marion London, 56, Sydney
Jason David Griffiths, 33, Coffs Harbour
Karla Michelle Mathews, 32, Coffs Harbour
Richard Aaron Elzer 32, Coffs Harbour
Gavin Brian Dallow, 53, Adelaide
Zoe Hosking, 15, Adelaide
Stuart Raymond Trott, 45, Melbourne
Krystal Browitt, 21, Melbourne
Julie Richards, 47, and her daughter Jessica Richards, 20