"As the energy travels from (150km) depth to the surface it loses a lot of its punch," he said.
"It wasn't a huge earthquake...you'd expect maybe some dishes or articles inside the house to fall over, maybe pictures might fall off the walls but we don't expect any structural damage."
Mr Fry said the tremor was significant but should not cause panic, and while aftershocks could be expected they should not be anything to worry about - although he added you could never be sure.
"As a general rule of thumb with an aftershock sequence you can expect one event that's one magnitude less than the main shock.
"So this was a 5.9, we might expect one 4.9 aftershock from it, then quite a few 3.9s, then even more 2.9s."
There were reports on social media that some people could hear the earthquake coming.
The quake was strong enough to get people out of bed and lots of comments were flowing on sites such as Twitter.
"Someone's just had a sizable quake. Felt strongly in Napier. Anyone else get the shakes?" wrote Mark Bramley.
A Fire Service spokesperson said there had been no call-outs or reports of damage following the earthquake, although GNS Science received a report from Havelock North that the quake had been "slightly damaging".
The quake followed a 3.5 magnitude quake at 6.19pm yesterday, centred 40km east of Taupo at a depth of 5km.
- With NZPA
