Local business owner and volunteer firefighter Tim Gibb said an earthquake on the fault could cause widespread damage.
"The main fault rupture is expected to be right through the middle of the Mobil station, the police station and one of the motels but nobody knows for sure."
The petrol tanks could lift out of the ground and rupture, causing fuel to flow through drains and roads, Gibb said.
"If that sparks then, the town would be levelled and go on fire. There would be no way of putting the fire out."
Over the last 8000 years, there has been a major earthquake on the Alpine Fault roughly every 300 years. The last one? 1717.
As a result of research over the last two decades, we now know that there is a 75 per cent likelihood of an earthquake on the Alpine Fault in the next 50 years, and an 82 per cent chance it will be over eight on the Richter scale.
This one — AF8, as it's called — we can prepare for.
DOC South Westland operations manager Wayne Costello said Franz Josef could lose access to services people use every day.
"Water, sewerage, power, all of that stuff is gonna be gone.
"We think we're gonna be isolated for six months. Every road bridge is gonna be out. All of the approaches will be gone. It's not just Franz Josef but all the way down to Haast."
One of the key things, Costello said, is looking after everybody as quickly as they can.
"If we have lots of people in town we'll try to get them away from here as quickly as possible because it's less burden for us while we stay here and try to put the pieces back together."
Geotechnical reports have recommended moving the entire township of Franz Josef a few kilometres up the road.
Orchiston is the science lead for the AF8 campaign — a collaboration between Civil Defence Emergency Management and Alpine Fault scientists to communicate the scientific evidence to the communities that need to hear about it.
Dr Caroline Orchiston, science lead for the AF8 campaign, says moving communities isn't something that is likely to happen in advance of an Alpine Fault earthquake.
"If you talk to people on the West Coast, they are very attached to their communities and their place. I wouldn't recommend anyone moves just because of the threat of this event but what I would recommend is that they work really hard to build their preparedness and their community resilience well in advance of this earthquake."
The AF8 campaign is a collaboration between Civil Defence Emergency Management and Alpine Fault scientists to communicate the scientific evidence to the communities that need to hear about it.
Costello says he doesn't think people in the area are ambivalent about it.
"I think they care about it because most people are doing things to be prepared.
"When you get in a car every day it's the same thing really, you're accepting there's a level of risk when you go out on the road but it doesn't stop anybody getting behind the wheel."