the last eruption in Aniakchak was a VEI 4 in  1931.  that's the little cinder cone inside the caldera.  it burned out all of the flora within the caldera, but the damage was pretty minimal.  It was about the same size as the eruption in iceland in 2010 that disrupted air travel for a month.  the big blast that created the 10 km caldera 3,700 years ago was a VEI 6 eruption (same size as Novarupta).