Extended Data Fig. 5: The impact of double subduction on the horizontal normal stress (x-direction) in the Japan region in the reference single and double subduction models (that is, the models presented in the main text).

For both models- single and double subduction - we present a horizontal slice (panels a, c) and along strike profiles of the horizontal normal stress at lithospheric depths from 20 km to 50 km (b, d). Panels a and c are equivalent to those of Extended Data Fig. 3 (with the location of the stress profiles marked). We annotate the mean horizontal normal stress (x-direction) of the profiles. At all depths, the introduction of double subduction approximately doubles the compressive stress magnitude.