Given that the topic of landslides came up during week 1 of the course, here is a little about my daily work on submarine landslide deposits.
First of all, how do we learn about submarine landslides? Seeing as the ocean is so large and we can’t really have any cameras permanently on the ocean floor with which to observe them, we have to primarily look at their aftermath (i.e. the material they leave behind). This material is often a number of meters thick, meaning we have to use specialist equipment to recover it, termed corers. These corers can penetrate from a few to a few hundred meters into the sea bed and retrieve a vertical section, giving us a look at what lies beneath. Here is an example of a core section showing a landslide deposit:
One important aspect of the study of landslides, one which was discussed in week 1, is prediction. The 2011 tsunami which struck the Eastern coast of Japan was caused by an earthquake-triggered landslide. Knowing the destruction that these events can cause, determining how often they occur is important in understanding when they might happen again. For this we need dating techniques. As some of you may know, dating is done using a number of methods, the most common of which is called radiocarbon dating. In order to gather material to date, we need to sample the material just underneath the landslide (landslides don’t tend to have any datable material), known as hemipelagic sediment, or ‘background’ sediment. This sediment contains the remains of a very important little group of organisms called Foraminifera, which we can use as datable material. Their remaining shells contain Calcium Carbonate, which contains carbon we can test and calculate an age based on the amount of radiocarbon remaining. Here are some Foraminifera ready to be picked. They’re pretty small!
Landslides generally occur many times throughout history in deep sea basins, and so build up on top of one another, with datable material in between. Once we have dates for the landslides we can begin to unravel the frequency of the events and compare the occurrence to climatic events, possible sediment loading from erosion and other possible triggering mechanisms.
Aside from the research, I act as a teaching assistant on a number of undergraduate modules, which is always a good laugh. I also edit the postgraduate newsletter, which is just a bit of a spoof really, but it’s good fun writing it.