Professor Ray Cas of Monash University's School of Geosciences said the world's biggest super volcano was Lake Toba, on Indonesia's island of Sumatra, site of both the recent massive earthquakes.
Cas told Australian media Friday that Toba sits on a faultline running down the middle of Sumatra -- just where some seismologists say a third earthquake might strike following the 9.0 magnitude quake on December 26 and Monday's 8.7 temblor.
Those quakes occurred along faultlines running just off Sumatra's west coast and created seismological stresses which could hasten an eruption.
Cas said Toba last erupted 73,000 years ago in an event so massive that it altered the entire world's climate.
"The eruption released 1,000 cubic kilometers (240 cubic miles) of ash and rock debris into the atmosphere, much of it as fine ash which blocked out solar radiation, kicking the world back into an ice age," he said.
The scientist said super volcanos represented the greatest potential hazard on earth, "the only greater threat being an asteroid impact from space".
"A super volcano will definitely erupt," he said.
"It could be in a few, 50 or another 1000 years but sooner or later one is going to go off."
Other super volcanos are found in Italy, South America, the United States and New Zealand -- where Mount Taupo could be ready for eruption.
"It has a big eruption every 2,000 years, and it last erupted about 2,000 years ago," Cas said.
The potential death toll from a super volcano eruption "could reach the hundreds of thousands to millions and there are serious implications on climate, weather and viability of food production," Cas said.
"The big problem is a lot of the volcanoes that potentially could erupt are perhaps not monitored to the degree that they should be, and of course we learnt that lesson from the Boxing Day tsunami disaster," he said.