Calderas By garikaib|2017-01-17T11:22:19+02:00June 8th, 2015|Landform Studies, Notes, O Level Geography, Ordinary Level Notes| El Boqueron caldera in El Salvador. Image credit Wikispaces.com ZIMSEC O Level Geography Notes: Calderas Calderas are very large craters often two or more kilometers in diameter that form at the top of volcanoes. They are often deep extending downwards for a few hundred […]Quick NetOne, Econet, And Telecel Airtime Recharge Number to recharge: Airtime amount ($): EcoCash number: Buy {{error_message}} {{error_message}} Read More Comments Off on Calderas