Evidence of active erosional processes in submarine canyons north of Molokai, Hawaii
In this project I propose to examine the erosional processes that helped carve the large submarine canyons that lie off the northern coast of Molokai, Hawaii. These high relief, steep-sloped, canyons were initially carved subaerially but continue to be eroded by landslides and turbidity currents. The prevalence, frequency, and initiation mechanisms of these submarine erosional processes are poorly understood in this canyon environment and in submarine canyons around the world. Earlier research shows that modern sediment accumulation rates, a primary driver for submarine landslides and turbidity currents, in these canyons are low. There is some sediment influx to the canyons, however, and combined with frequent earthquakes and steep canyon slopes, I hypothesize that erosional processes remain active. To test this hypothesis, I will create high-resolution bathymetric maps of the canyon floor using a multi-beam sonar system and examine sub-surface layering using a 3.5 KHz bottom profiler. I will take box cores in erosional paths and depositional areas as they are identified from the bathymetric data. Grain size analysis and X-radiographs will be used to classify sediments and to differentiate between landslide and turbidity current deposits. Lastly, I will do 210Pb dating of evident depositional layers to determine frequency or timing of the last large erosional event. This research is significant not only in giving insight into the processes that are active in these canyons, but in other areas around the world where sediment accumulation rates are low.