This 7 March 2005 Envisat MERIS image shows the unusual phenomenon of the simultaneous eruption of two stratovolcanoes, Kliuchevskoi and Shiveluch (or Sheveluch) on Russia's Kamchatka Peninsula. Stratovolcanoes are formed of alternating layers of pyroclastic materials and subordinate lavas. They have conical shapes and are built up by multiple eruptions. The lava produced during stratovolcano eruptions is typically andesitic, with fine grains and dark colour. Andesitic eruptions tend to be explosive, producing pyroclastic materials and in some cases 'ignimbrites' - fist-sized pumice fragments. The Reduced Resolution mode image has a 300 metre resolution.