The strike of the Apennine subduction zone forms a long, irregular arc with centers of curvature in the Tyrrhenian Sea following the hanging wall over which the mountains have been raised; i.e., the eastern wall of the mountains. It runs from near the base of the Ligurian Apennines in the Po Valley along the margin of the mountains to the Adriatic, along the coastal deeps of the Adriatic shore, strikes inland at Monte Gargano cutting off Apulia, out to sea again through the Gulf of Taranto, widely around the rest of Italy and Sicily and across inland north Africa. The upper mantle above deep is broken into the "Northern Apennines Arc" and the "Calabrian Arc", with compressional forces acting in different directions radially toward the arcs' centers of curvature. The overall plate tectonics of these events has been modeled in different ways but decisive data is still missing. The tectonics, however, are not the same as those which created the Alps.