Fig. 8: Slope-parallel seismic reflection SPARKER profiles collected post-collapse in August 2019.

Profiles SKS-01 (A), SKS-02 (B) and SKS-04 (C) also show the emplacement of a large landslide mass on the seafloor and its incision into the seafloor. Profile SKS-01 (A) shows the emplaced and buried debris flow found distally from the main landslide body. Profiles SKS-02 and SKS-04 (B and C, respectively) show the more proximal landslide deposits as large blocks that incise the seafloor, Also shown is the projected time-converted level of the 1990 seafloor (based on Deplus et al.¹¹ bathymetry) to demark the sedimentation in the basin since that time. All horizons are marked in the same way as Fig. 7. Insets represent magnified images of the debris flow and are represented in Supplementary Fig. 11.