The Harrat al Birk volcanic field, also known as Harrat Hayil or Hubhub al Sheikh, is the only Saudi Arabian volcanic field that lies directly along the Red Sea coast. It covers an 1800 km2 area west of the town of Abha and separates the Tihamat ash Sham and Tihamat 'Asir coastal plains. Volcanic activity dates back to the Miocene and concluded with the formation of Holocene cinder cones (Brown et al., 1984). The Quaternary lava flows are of basaltic to trachybasaltic composition and contain ultramafic inclusions. Cinder cones are scattered throughout the volcanic field, with a few late-stage cones (Ba'a and Qishr) NE of the main lava field. Isolated patches of freshly eroded ash surround a vent at Jabal Ba'a, east of the main field, suggesting an eruption during the last century.