Communities should be planning, even if there is no chance of a major earthquake and tsunami occurring, Professor Johnston said.
"If an earthquake is nearby the only warning will be nature itself," he said.
"While a tsunami warning will help in the case of more distant earthquakes, you have to understand the nature of a quake like you've never known before which will shake for a minute. You will know that Pacific/Australian Plate has gone and you will have 15 to 20 minutes' travel time, which gives you time to move a relatively short distance here in Akitio."
The estimated probability of a massive earthquake under central New Zealand has risen due to a rise in slow-slip (silent earthquake) activity, but such a quake remains "very unlikely".
GNS Science said the chance of a quake as big or bigger than the magnitude 7.8 Kaikoura earthquake in the coming year had now been put at 5 per cent - up from 3 per cent. That is about six times higher than the probability before the November 14 Kaikoura quake.
The rise in the probability was because of ongoing slow-slip events after the earthquake on a large area of the tectonic plate boundary underneath the North Island.
They take place over weeks or months without any shaking detectable by people or seismographs. Instead they are detected by a network of GPS stations around the country run by GeoNet and Land Information NZ.
"That plate is about 20km to 30km out to sea off the East Coast at the boundary where the Pacific Plate goes under the Australian Plate," Professor Johnston said.
Since the Kaikoura earthquake five different research organisations are looking at responses to earthquakes and a tsunami warning.
"It's a great opportunity to share knowledge and risk preparedness," Professor Johnston said.
"While the risk may not be more before the Kaikoura quake, we should have these conversations about good planning and managing risk. This is about empowering communities."
With the real threat to low-lying coastal areas if a tsunami occurs, the researchers have been studying why some communities in Japan survived the massive magnitude 9 earthquake in March 2011. While 6000 people perished, those able to self-evacuate survived.
"It's about preparedness - the ability of a community to make a plan," Professor Johnston said.
Massey PhD student Miles Crawford is studying tsunamis and how to communicate risk to residents.
Kate Boersen, the community science co-ordinator for East Coast LAB (Life at the Boundary), said she loves her job.
"It's about finding out new research and communicating it with communities," she said.
East Coast LAB is an initiative which aims to improve the resilience of communities on the East Coast of the North Island to natural hazards associated with the plate boundary.
Tararua District Council resilience manager Paddy Driver will be erecting 2m-high signs at Herbertville and Akitio beaches on Monday, with posters available for visitors to make them aware of the risks, with action plans for both coastal villages.
GeoNet scientists have said the Hawke's Bay-Gisborne region slow-slip event only lasted about a week and has mostly finished. Slow-slip events in these regions happen less than 15 kilometres deep.
There were a number of earthquakes offshore Porangahau in the two to three weeks after the Kaikoura earthquake which were likely triggered by the east coast slow-slip event.