Why is the Arabian tectonic plate so stable and not rifting apart?

What is it about?

The rifting of continents has been suggested to be in part due to the impact of giant hot plumes in Earth's mantle when they reach its surface. E.g., a plume rising in the Afar region between Africa and Arabia has been suggested to have opened the Gulf of Aden, Red Sea and East African Rift, in a giant Mercedes-star arrangement. Apparently, this occurs when the plume pushes up Earth's surface, causing the plate to break up as it slides away under gravity, and because it weakens the more solid outer part of the mantle (lithosphere). Giant dikes may also be needed to break lithosphere. A giant line of active volcanoes runs almost due north from a place east of Jeddah in Arabia (Makkah-Madinhah-Nafud volcanic line; Figure 1). Underneath this line, the upper mantle is hotter than usual (seismic velocities are unusually slow). These observations have suggested to some researchers that Arabia is about to split into two, the rifting leading to a new ocean basin between them. If we wait around a few 10s of millions of years, Arabia could turn out to be smaller, with Jeddah and northwest Arabia forming a new micro-continent. Perhaps the Arabian plate is also being pulled northwards by an old plate sinking beneath the Iranian Plateau, providing the force for rifting. However, GPS measurements have revealed no movement across the Makkah-Madinhah-Nafud volcanic line. Furthermore, earthquakes tend to occur around the margins of the Arabian plate and rarely within it. Arabia therefore appears to be rigid. We undertook a study of stresses within the plate by compiling a map of the directions of maximum horizontal compressive stress (SH). Most SH indicators are from the failures of boreholes, though some are from earthquakes (focal mechanisms) and from orientations of dykes. The map (Figure 2) reveals that the Iranian Plateau is resisting the northwards movement of Arabia, hence SH is oriented towards Iran. SH should be parallel to Arabian/Persian Gulf if there were a subducting slab there. SH is also oriented away from the Afar generally, suggesting that the plume is still pushing Arabia northwards. SH is oriented across the rift in the southernmost Red Sea, where rifting appears therefore to be dead, as confirmed by GPS measurements.

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Why is it important?

Arabia will therefore not be forming a new ocean basin soon, as there is no force from slab pull beneath the Iranian Plateau. Push from the Afar and resistance from that plateau appears to have put Arabia in a general state of compression. Rocks tend to be stronger under compression than extension, hence there are few earthquakes within Arabia and little observable movement.