Also found in: Wikipedia.
Alba Patera(al -bă) Probably the largest central-vent volcanic structure on Mars. Located north of the Tharsis Ridge, it is centered on the aerographic coordinates 40° N latitude, 109° W longitude (see areography). It has a low dome containing a central caldera and enclosed by a ring of fractures 600 km in diameter. Associated lava flows cover an area more than 1500 km across. See Mars, volcanoes.
Collins Dictionary of Astronomy © Market House Books Ltd, 2006