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Few people have been counting how many have struck in the past two weeks, but scientists say the tremors show the stresses at work that would eventually unleash a monster quake.
Nobody knows exactly when this would happen, but the Big One could be as devastating as the December 2004 earthquake and accompanying tsunami which killed 230,000 people.
When the tsunami tore across the Indian Ocean on Dec 26, 2004, it displaced 1.7 million people and damaged over US$10 billion (S$15 billion) worth of infrastructure and property in South-east Asia, Sri Lanka, India and as far away as east Africa.
Not only is the looming monster quake expected to be stronger than the biggest of this month's deadly quakes - an 8.4-magnitude temblor - but it is also likely to trigger a devastating tsunami, they say.
Earthquake expert Danny Hilman Natawidjaja, of the Indonesian Institute of Sciences (Lipi), said: 'We all agree that a quake of at least 8.5 is imminent within the next few decades.
'Historical records show that a tsunami would be likely.'
CNN quoted earthquake geologist John Galetzka, who is also studying the area, as saying pressure has built up to such a degree that sooner or later it has to release in the form of a 'giant earthquake'.
And he told CNN he believes such an event is likely to happen sooner rather than later, and could exceed a 9-magnitude.
A study, published last December by the American National Academy of Sciences, had warned that a tsunami triggered by such a quake could threaten the lives of more than a million people living south of the equator on Sumatra's west coast.
That, it pointed out, is about twice the pre-2004 population of the west coast of Aceh, which bore the brunt of the tsunami three years ago.
The team of scientists from the University of Southern California, the California Institute of Technology, and the Technical University of Crete used computer modelling techniques to recreate past tsunamis, and simulate possible future events.
Their study produced four plausible scenarios which could see the quake sending waves crashing as far as 3km ashore.
The team said: 'Potential losses could be as great as those that occurred in Aceh in 2004.'
The scenarios used for the study centred on ruptures along a segment of the same big fault - called the Sunda megathrust - that caused the 2004 Aceh tsunami and the Nias quake of 2005.
Ruptures along this segment, under the Mentawai islands off the south-western Sumatran coast, also produced two great quakes and tsunamis in 1797 and 1833.
And Lipi's Dr Natawidjaja points out that big quakes appear to recur on average every 200 years or so, meaning the time is about right for another one.
Although details of casualties for the two earlier events are sketchy, it was recorded that the 1797 tsunami killed about 300 people, although the population at that time is thought to have been a few thousand.
The wave is also reported to have carried a 200-tonne British ship close to a kilometre inland in Padang.
Less is known about the deadly waves that struck the coast in 1833, nearer to Bengkulu town in Sumatra, and about how many were killed in that incident.
Apart from the risk of tsunami, a big quake from what is called the Mentawai patch, off Bengkulu town, could trigger volcanic eruptions nearby and along the inland Sumatran fault.
Dr Prih Harjadi of the Indonesian Meteorology and Geophysics Agency suggested: 'Earthquake-induced deformations in the earth's crust could increase the stresses already building up nearby... leading to a pressure build-up and, ultimately, an eruption.'
And there are more than 30 active volcanoes on Sumatra.
Given his level of knowledge about the stresses at work in the area, Mr Galetzka says: 'Whenever I am in Padang I think about my escape routes, almost every moment.'
