With 125+ active and dormant volcanoes Indonesia at any given moment usually has 1-2 erupting and another half-dozen rumbling; what was odd the last few months was none at all, really.
All of the various volcanoes either erupting or having seismic activity (Talang, Anak Krakatau, and Tangkuban) have a history small eruptions fairly often.
That, in turn, was created where formerly had stood the "landbridge" between Sumatra and Java ~ that's back when they were still one island.
That's the explosion that appears to have been a "cause" of the economic collapse that brought about the Dark Age beginning in 538 AD.
Krakatoa may also have small explosions from time to time, but over the last few thousand years it's had more than it's fair share of big, Earthshattering, civilization destroying hum dingers.
Then there's Mt. Hekla in Iceland. Isn't even a sign of people living there before it's discovery in the 900s! Actually, there's no sign of anything living there before then either. That's the volcano suspected of bringing on the so-called "Greek Dark Age" back in the BCE period.
We should all pray that Krakatoa does not explode.