Characteristics and frequency of large submarine landslides at the western tip of the Gulf of Corinth

Coastal and submarine landslides are frequent
at the western tip of the Gulf of Corinth, where small to
medium failure events (106–107 m3/ occur on average every
30–50 years. These landslides trigger tsunamis and consequently
represent a significant hazard. We use here a dense
grid of high-resolution seismic profiles to realize an inventory
of the large mass transport deposits (MTDs) that result
from these submarine landslides. Six large mass wasting
events are identified, and their associated deposits locally
represent 30% of the sedimentation since 130 ka in the
main western basin. In the case of a large MTD of 1 km3
volume, the simultaneous occurrence of different slope failures
is inferred and suggests an earthquake triggering. However,
the overall temporal distribution of MTDs would result
from the time-dependent evolution of pre-conditioning
factors rather than from the recurrence of external triggers.
Two likely main pre-conditioning factors are (1) the reloading
time of slopes, which varied with the sedimentation rate,
and (2) dramatic changes in water depth and water circulation
that occurred 10–12 ka ago during the last post-glacial transgression.
Such sliding events likely generated large tsunami
waves in the whole Gulf of Corinth, possibly larger than
those reported in historical sources considering the observed
volume of the MTDs.