Most hot springs in western Saudi Arabia are associated with the volcanic Harrats, as most springs are situated in areas adjacent to the Harrats towards the Red Sea. Rain water infiltrates the fractures and seeps into the subsurface and accumulates at depths near the magma chamber. As a result, water is heated and flows upward through the cracks due to pressure.
Thermal activities along the Mecca-Madina-Nafud (MMN) volcanic line are manifested in the form of hot springs, fumaroles, and the occurrence of hot water pools close to the surface of the earth. The presence of steam that emanates from the openings and cracks in some volcanic Harrats located along the MMN volcanic line, such as Harrats Khaybar and Ithnayn were previously observed. This steam can only be seen at dawn during the winter, because its temperature is less than 50o Celsius. Thermal activities in the form of hot springs in some locations along the Red Sea coast, such as in Al-Laith, 150 km south of Jeddah were likewise observed. Detailed studies are required to take advantage of all these thermal sources to produce electric power along the MMN volcanic line.
A fumarole in an eroded lava flow in the Harrat Khaybar north of Madina. The photograph was taken on February 8, 1992 AD (5/8/1412H), during which the ambient temperature was measured at 6°C and the steam temperature was 25°C.
Areas of high thermal activities in western Saudi Arabia