Above I attached some things images that I found to be important to this situation.
Early 1930s - The start of renovations and filling on riverside avenue to make it look nicer.
Early 1940s - development starts alongside riverside avenue.
1955 - Large landslide
by 1962 - the gully behind delehanty hall had been filled in, and more development was taking place.
Possible landslides since then: 1968, 1972, 1984, 1981
2019 - Landslide
Adding fill onto an already unstable bank only increases its likelihood of creating a landslide. Combined with development and loss of trees only makes the chances higher. This spot isn't ideal for this type of treatment, considering it is on the outside of the river where the cut bank is present. It is always undergoing erosion