Ms Wallace stressed they did not know "the risk posed by the Hikurangi fault subduction zone" and "people should not freak out".
"Like in any emergency, people should prepare and plan and have an emergency kit. If it is a large or long earthquake, move to higher ground.
"What we did see using GPS sensors is that the Kaikoura earthquake triggered slow slip on the Hikurangi fault subduction zone."
Hawke's Bay Civil Defence Emergency Management group manager Ian Macdonald said it was a "rare event" that could cause "shaking and liquefaction".
"The challenge is that it could also create a tsunami that could arrive in 20 minutes or so, similar to Japan."
He said they were talking about an "event occurring within a 1000-year time frame" - that is a .01 chance every year.
It is believed to be a different type of earthquake to the one experienced in Napier in 1931, as it was on a fault line and not on a subduction zone, Mr Macdonald said.
"The 1931 earthquake did not produce a major tsunami, whereas a megathrust could produce a major tsunami. Our models say up to 13m."
He said long, or strong, get gone was the message in the event of an earthquake.
"If it is long - over one minute or strong enough to make it difficult to stand up, you should immediately head inland or for higher ground. Don't wait for official warnings, just get out."
Last year's Kaikoura earthquake triggered a large slow slip event off the East Coast covering an area of more than 15,000sq km.