I looked up the different types of volcanic eruptions and found that this eruption most closely matches the description of Plinian eruptions. Volcanoes in this category include Mt. Vesuvius, Mount St. Helens, and Mt. Fuji. Incidentally, Mt. Fuji is over 3 km tall, and the first estimate of the mountain's height in this thread put it at around 3 km tall.Giratina93 wrote:Alas, we don't know enough to make a definitive statement on how strong the eruption is. To accurately measure how strong a volcanic eruption is, you need to know what type of eruption occurs, and what the magma involved is made of. The magma seen in the episode doesn't seem very viscous, so the eruption strength probably isn't all that impressive as far as volcanoes go. The more viscous the lava, the greater the explosion, and the more power and force behind the eruption. The closest example to what is shown would probably be a hawaiian eruption, which is for all intents very tame. However, the eruption shown doesn't quite match any one example, so accurately gauging it is hard when almost no other volcano currently active acts like a mix of Hawaiian and Strombolian, both which are again, very mild by volcano standards.
As for the destruction of the island, it seems more like once the eruption was underway, the island sort of caved in on itself rather than completely be blasted apart, which further makes trying to identify how strong it is a near impossibility.
Another indicator of strength is the amount of ash spewn out of the volcano, and this one had massive ash clouds rising miles into the air in its last shot. The eruption was also strong enough to blow up a large portion of the mountain if not virtually all of it, which is far from mild.