Wow, talk about the fury of nature...
A time video from YouTube channel PhotoVolcanica shows an incredible display of three tornadoes in the wake of an eruption at Indonesia's Sinabung Volcano.
According to the site, "the pyroclastic flow deposits red-hot material on the slope of the volcano. After a few minutes, air heated by the deposit establishes a convective regime and due to the speed of the rising air a series of small tornados are formed."
It's hard to tell just how how the volcanic flow is during daylight, so they've posted a nighttime video of the same volcano for reference (this one is sped up 5 times normal speed.)