[link to rsta.royalsocietypublishing.org]

Landslides on ocean-island flanks have been cited as posing a tsunami threat on a trans-oceanic scale (Ward & Day 2001), potentially comparable in magnitude to or even larger than the 2004 Indian Ocean tsunami (Lay et al. 2005). While this extreme scenario can be questioned (Mader 2001; Wynn & Masson 2003), there is little doubt that the threat posed by ocean-island flank landslides is both real and significant. "


And here is another interesting piece on dike intrusion and failure of volcanic flanks:

[link to www.ems.psu.edu]