On April 6, Australian man Tyronne White posted on his Facebook page that he was about to embark on a three-week trek between Kathmandu and the Chinese border.

"See you all on the other side. Salud!!" wrote the adventurer, who is originally from Taree on the NSW mid-north coast, but who has been travelling throughout the world for the past eight years.

April 27 - today - marks three weeks since the 44-year-old set off on that trek and his anxious family and friends are waiting and hoping for any news that he is safe following a devastating 7.8 quake that hit Nepal on Saturday. At least one Australian is reportedly among the thousands of people who were killed.

"We're a pretty close-knit family and we're trying to keep our chins up," said his cousin, Marc Wade Patek, from Sydney.

"As a family we're just trying to rally together and stay positive, but his mother is a mess. He would phone home, if there was any way possible. He would definitely be trying to do that."

The family  hopes he has not contacted home because he is still trekking and may not even know the extent of the tragedy that has struck the mountainous nation.

"Hopefully they're just out of communication range. But it gets a bit scarier each day," Mr Patek said.

"He's a very sensible traveller. He's been in situations that would scare the hell out of us. We all just want to know that he's safe and sound wherever he is."

Holly Ulmer, from Newcastle, is one of the lucky ones who received a 20-second phone call from her boyfriend, Liam Buxton, to say that he was safe.

Mr Buxton, 25, and two friends, Peter Cossar and Nick McLennan, also from Newcastle, were on a 13-day trek from Lukla​ to Everest base camp and were believed to be just one day away from reaching the base camp, when the earthquake struck.

"Twenty four hours later and he could have been one of the people who were horribly affected," said Ms Ulmer.

"It was horrible, just not knowing whether or not they were  OK. I spoke to the tour company in the early hours of Sunday morning and they advised that everyone on that tour had been accounted for.

"Then at 11pm last night I got a short, 20-second phone call from Liam. He had used someone's satellite phone to say they were in Namche Bazaar.

"They're all very shaken up but thankfully everyone is fine on his tour group."

More than 830 Australians who were in Nepal when the quake struck on Saturday are safe, Foreign Affairs Minister Julie Bishop said earlier.

But authorities are still trying to contact many more from the 1250 families and friends who have reported Australians  missing  in Nepal.

The official death toll in Nepal from the  massive weekend earthquake has risen to 3218, with 6500 injured, Nepal's disaster management chief Rameshwor Dangal said.

About 90 people are also known to have died in neighbouring countries, including India and China.