Emergency services based on top of the Alpine Fault in Franz Josef must be urgently moved, the Westland mayor says, after latest research indicates a devastating quake in the next 50 years is more than twice as likely as previously thought. Franz Josef township, on the West Coast. Photo: RNZ / Conan Young The study from Victoria University suggested a big quake could block South Island highways in more than 120 places, leave 10,000 people cut off, and cost the economy about $10 billion. The 850km Alpine Fault runs up the western side of the South Island between Milford Sound and Marlborough, and poses one of the biggest natural threats to New Zealand.