Steam Explosions Rock New Zealand's Rotorua Caldera

Steaming volcanic gas vents on the shores of Lake Rotorua near the city of the same name in New Zealand. Taken in 2009.Erik Klemetti The North Island of New Zealand is chock full of volcanoes---and big volcanoes at that. No less than four major calderas sit in the Taupo Volcanic Zone (TVZ) that stretches from White Island in the north to Ruapehu in the south. One of the most violent volcanic eruptions in human history took place in ~186 AD from Lake Taupo. That rhyolitic (high silica) eruption produced an ash plume that may have towered 50 kilometers (164,000 feet!) over the caldera, what we call an "ultraplinian" eruption (and anything that is "ultra" has to be big). More recently, Tarawera in the Okataina caldera erupted in 1886 in one of the most explosive basaltic (low silica) eruptions on record that had ash plume that reached 10 kilometers (~32,000 feet) ...