This volcanism is related to the rifting of the Arabian and African plates and the formation of the Red Sea. Prior to rifting, the area was a stable craton . Volcanism began about 40-50 million years ago as the crust was stretched laterally. Most of the rifting and volcanism has occurred in the last 30 million years. In the last 5 million years, volcanism along the divergent plate boundary beneath the Red Sea has produced tholeitic basalt , similar to basalts at mid-ocean ridge.
Volcanism is distributed asymmetrically with respect to the Red Sea.
Large areas are covered with basalt on the Saudi Arabian Plate. No volcanism has occurred at similar latitudes on the African Plate. Photo courtesy of the U.S. Geological Survey. Volcanic vents of the Harrat Hutaymah volcanic province. Numbers indicate locations mentioned in the text.