Landslides in the Seacliff-Kilmog Hill area, East Otago, New Zealand

Jones, Anthony F. E. (Anthony Francis Elliott)

Slope failures in the Seacliff- Kilmog Hill region are a major issue. They affect the road and rail networks that are a major lifeline to the city ofDunedin. State Highway 1 runs through this area and was realigned in the late 1960s. This led to slope stability issues such as the Site Office Slide. The underlying geology of the area is dominantly made up of the clay rich Onekakara Group, with knobs ofvolcanics and sandstones resting on top. The abundance of Onekakara Group located at the surface is the main reason behind slope stability issues found in this area. Analysis revealed that slope failures dominantly occur in the southeast direction, and less so in the northwest direction. Low angle slopes were shown to offer little resistance to slope failures, with the majority of failures occurring between 1 0 - 20 degrees. Mass wasting is occurring on a large scale with 3 - 4 large landslide complexes, slowly creeping towards the coast. Within the debris of these complexes slope failures are common and generally occur as debris flows. A simple landslide hazard map was produced and indicated regions of high, medium and low risk. It was found that the majority of SH 1 lies within the high-risk category. Residential areas at Warrington and baches along the coast lay within the low risk category. This may have implications for future development in the area, but it is suggested that the hazard map be used as a qualitative guide to susceptibility to slope failures.

50 Leaves. Ill.(some col). Maps (folded in pocket); 30 cm.

2006Jones_A

Abstract Only

POLYGON ((170.667556083684985 -45.648633678348574,170.608295575084298 -45.716516952971503,170.551494081994804 -45.715011268401042,170.556400753985855 -45.646912454014121,170.667556083684985 -45.648633678348574))