The lowest point of Earth is found at the Dead Sea, so some particular conditions must be prevalent there. Looking at the mantle convection pattern, some explanations can be made.
The main division line, as defined here, is actually at the western margin of the Nile Delta. This particular main division line, marked with slightly wider red line than the others, is not of a single origin, according to the convection rolls model. First, it is a main division line of the convection rolls of the outer core. Second, it is a division line of the lower set of convection rolls found between 265-410 km depth. The rolls of the upper set (between 120-265 km) and the lower set interact, as the division lines almost coincide at these latitudes.
The Nile is kept in an incredible way on its northwards path with this system, and the main part of the delta is found in between two cooperating downwelling lines. Farther to the east, this combination of convection rolls marks the beginning of the Great Rift Valley system with the Dead Sea fault line. As can be seen, the relevant upwelling division line is quite parallel to the Dead Sea fault, but is found slightly west of it, except at the intersection point of the upper and lower convection rolls, where the rift system shifts to the west of the convection rolls division lines.