The lower, up to 100 m thick, glacimarine unit (HLU) is suggested to be of Younger Dryas age.

The < 55 m thick upper seismic unit (HUU) is dominated by 19 postglacial MTDs.

The Early Holocene (11300-8200 cal. yrs BP) is characterized by six regionally-triggered and nine regionally- or locally-triggered MTDs.

The mid-Holocene (8200-4100 cal. yrs BP) was a quiet period with respect to submarine mass movements.

A reactivation of submarine mass movements has been observed in the Late Holocene (4100 cal. yrs BP to present).

The large submarine Storegga Slide event might have impacted the Inner Hardangerfjorden system.

Postglacial MTD recurrence intervals are estimated to be 1/200 years in the Early Holocene and 1/1000 years for the Late Holocene.

Since 2400 cal. yrs BP the Hardangerfjorden system has not been impacted by large mass failures.