Depth: 4.89 km
The Arabian Plate is one of the tectonic plates that form the earth’s crust. It moves northeastward as a result of the eruption of magmas along the Red Sea rift, which spreads annually at a rate of approximately 15 mm. This spreading center produces many earthquakes along its boundaries with the surrounding plates, such as those along its eastern and northeastern margins that form the Zagros Mountains in Iran or along its northern margins in Turkey, which was hit by a devastating earthquake on August 17, 1999 that claimed the lives of nearly 20,000 people, injured more than 40,000, and displaced over a quarter of a million people, in addition to huge material losses, which was estimated to be in the billions of dollars.
Saudi Arabia is part of the so-called Arabian Plate. It is bordered by three types of tectonic boundaries: divergent, convergent, and transform fault boundaries. The Arabian Peninsula constitute as the largest part of this plate, hence, its name. The plate is bounded from the west by the Red Sea floor spreading zone and from the south by the Gulf of Aden floor spreading zone, and in both regions, these parts of the Arabian Plate are larger. The Zagros and Makran Mountains in Iran and the Taurus Mountains in southern Turkey are, respectively, the eastern and northern boundaries of the Arabian Plate, which are classified as convergent plate boundaries that represent the zone of collision between the Arabian Plate and the Eurasian Plate. The Arabian Plate is bounded from the northwest by a left-lateral transform fault boundary, called the Dead Sea Rift, that extends from the northern end of the Red Sea to the Taurus Mountains in southern Turkey through the Dead Sea. The plate is bounded from the southeast by a right-lateral transform fault boundary that extends from the eastern end of the Gulf of Aden to the eastern end of the Makran Mountains, called the Owen Fault. The Arabian Plate moves northeasterly between the abovementioned transform fault boundaries, causing, on the one hand, the expansion of the Red Sea and the Gulf of Aden, and on the other hand, the plate collisions at the Makran, Zagros and Taurus Mountains. The distribution of earthquakes is concentrated at these boundaries of the Arabian Plate. Most of these earthquakes occur along the Gulf of Aqaba, the Dead Sea, the middle of the Red Sea, the Gulf of Aden, and along the boundaries between the Arabian and Iranian Plates.
The basement rocks in Saudi Arabia, or the so-called Arabian Shield, cover about one third of the Kingdom’s land area, while the sedimentary rocks, or the so-called Arabian Shelf, cover the rest of the Kingdom. The volcanic flows occupy large areas of western Saudi Arabia, including the holy cities of Mecca and Madina. Geologic structures, such as old and recent surface and subsurface faults and folds are spread throughout the Kingdom, especially in its western parts. Some studies suggest that some internal regional faults may be extensions of some transform faults in the Red Sea.
The boundaries of the Arabian Plate relative to its neighboring plates (Johnson, 1998).