Alba Mons, located in the northern Tharsis region, is a unique volcanic structure, with no counterpart on Earth or elsewhere on Mars. The flanks of the volcano have extremely low slopes characterized by extensive lava flows and channels. The average flank slope on Alba Mons is only about 0.5°, over five times lower than the slopes on the other Tharsis volcanoes. The volcano has a central edifice 350 km wide and 1.5 km high with a double caldera complex at the summit. Surrounding the central edifice is an incomplete ring of fractures. Flows related to the volcano can be traced as far north as 61°N and as far south as 26°N. If one counts these widespread flow fields, the volcano stretches an immense 2000 km north-south and 3000 km east-west, making it one of the most areally extensive volcanic features in the Solar System. Most geological models suggest that Alba Mons is composed of highly fluid basaltic lava flows, but some researchers have identified possible pyroclastic deposits on the volcano's flanks.