Red Cross has activated its Family Links Website in the wake of the White Islands disaster, and has received more than two dozen posts from worried family members.
Among the registered missing by concerned family includes a 72-year-old Australian man last seen aboard the Ovation of the Seas cruise.
Australian nationals were among those reported on the website as being on the cruise ship.
The Family Links site allows people seeking information about a loved one, or who cannot make contact with them after the eruption, to register details on the website.
People can also register themselves as safe after the eruption.
"If you are worried about a friend or family member following this eruption, first contact them as you normally would," Red Cross advised on its website.
"Using your own channels can help to speed the process up and helps response agencies too. If you have lost contact with a family member or friend following the eruption, you can register them as missing."
Red Cross also advised people to update information on those that have been previously registered as missing on the website.
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• Scientist: White Island eruption was 'basically instantaneous'
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