Complex sentence: By way of comparison, the 1980 Mount St. Helens eruption was at the lower end of VEI-5 with 1.2 km 3, and both Mount Pinatubo in 1991 and Krakatoa in 1883 were VEI-6 with and DRE, respectively.
Split into simpler sentences: By way of comparison, the 1980 Mount St. Helens eruption was a VEI-5 with 1.2 km 3 of ejecta. Both Mount Pinatubo in 1991 and Krakatoa in 1883 were VEI-6 with and DRE, respectively.