**4. Intra-arc basin development in response to tectonic events: A case study from the Ou Backbone Range**

This section focuses on the post-rift tectonic events based on a case study of intra-arc basin development from the Yuda Basin in the Ou Backbone Range (Figure. 2).

**Figure 4.** Index map of the Akita Basin and the Ou Backbone Range showing regional geology. SF: Senya Fault, KWF: Kawafune-Warikurayama Fault, EMF: Eastern Marginal Fault, KYT: Kitayuri Thrust.
