The Ma Alalta stratovolcano, also known as Pierre Pruvost, is located well to the west of the Danakil depression at the foot of the regional Ethiopian scarp, between two large horsts of uplifted basement blocks. A large trachytic and rhyolitic stratovolcano at the center of the complex contains nested oval-shaped summit calderas, 8 x 5 km and 5 x 2.5 km. Ignimbrite deposits, perhaps associated with formation of the larger caldera, extend beyond the volcano primarily to the NE and SE. Young basaltic lava flows were erupted on the NW, SE, and E flanks. Recent silicic activity has produced pantelleritic obsidian domes and lava flows on the southern flank. Fumarolic activity continues at one of the domes.