Be happy this big quake happened at the Western end of Sumatra, and not the Eastern end. That's where Krakatoa is located! One explosion possibly brought about the Dark Ages in 538 AD.
Professor Mike Baillie believes it was a comet fragment(s) that brought on the Dark Ages.
Indonesia is also home to the famous Toba supervolcano, one that last erupted about 75,000 years ago. Some anthropologists who have studied mitochondrial DNA passing through human generations note that there was a drastic drop in the number of mitocondrial strains in humans around 75,000 to 74,000 years ago, closely matching the last major eruption of Toba. This meant that the Toba eruption may have come very close to wiping out the human race because of Toba's eruption effects worldwide.
This earthquate occurred closer to a much larger, by several orders of magnitude, and potentially more dangerous "super" volcano TOBA. The good news is, it's been quiet for the last 75,000 years.