Hilina slump area, 2001 | WHAT REALLY HAPPENED

Hilina slump area, 2001

n 1868 and 1975 this region moved abruptly several to tens of meters during major earthquakes (M7.9 and M7.2, respectively) with attendant destructive tsunamis. The tsunami generated in both 1868 and 1975 resulted in extensive damage and fatalities on Hawaii, and the 1975 tsunami produced minor damage in California. The possibility exists that future detachments of this type, or far more extensive and catastrophic debris avalanches, will occur in the future. The entire south flank of the island shows evidence for slumping and collapse. This proto-slump has now broken into two slumps that are buttressed in the middle by Loihi Seamount. These slumps are the Punaluu slump west of Loihi and the Hilina slump east of Loihi. The presence of debris-avalanche deposits along adjacent island flanks indicates the potential for catastrophic failure of such unstable slopes. The continuous creep and incremental movement associated with the large earthquakes are apparently driven by both magmatic processes within the active volcanoes and gravity. However, the mechanisms by which these slowly creeping slumps fail catastrophically are unknown, as are the precursors to such activity.