BIGGER isn’t always better when it comes to volcanoes. Mount Vesuvius in Italy and Mount St Helens in Washington state are hardly giants, but for the scale and destructive power of their eruptions they are hard to beat. Ol Doinyo Lengai, some 120 kilometres north-west of Arusha, Tanzania, in east Africa’s Rift Valley can pack a punch too. Three times during the last century it propelled boulders and dense columns of ash several kilometres into the air.
But this is not what gets geologists most excited. Ol Doinyo Lengai (the name translates as Mountain of God) is the only volcano…
