**4. Monitoring slow earthquakes in shallower part by DONET**

Recently, slow earthquakes have been also observed in shallower part of subduction plate boundaries (e.g., Hirose et al., 2010). As seen in Figs. 9d and 9e, stress shadow of LA has more effective on shallower part of transition zone. This means that preseismic change of slow earthquake may be more sensitive in the shallower part. In this section, we develop a model of slow earthquake migration in shallower part of transition zone in addition to deeper part, discussing the detectablity of Dense Oceanfloor Network System for Earthquakes and Tsunamis (DONET) toward an anticipated Tonankai Earthquake (Fig. 10).

Fig. 10. An overview of Dense Oceanfloor Network System for Earthquakes and Tsunamis (DONET) in Tonankai region.
