Map reveals danger from quake-made dams

Dams created by landslides in this month's 7.8 Kaikoura Earthquake have been pin-pointed on a detailed new map created by GNS Science and Environment Canterbury.

Source: Environment Canterbury

The November 14 quake and subsequent aftershocks have triggered numerous landslides throughout North Canterbury, some of which have dammed rivers and streams, and downstream areas were at risk of flooding and debris flows if dams broke.

Crews from GNS Science have been identifying the landslide dams, doing extensive visual surveys and mapping threatened spots.

It found some sites were much more threatening than others.

There were "high chances" of failure at dams in the Linton, Towy and Conway rivers, where dam faces were beginning to erode, and "moderate" chances of failure at dams in the Gelt, Hapuku, Leader, Ote Makura and Stanton rivers.

And although the mapping had been comprehensive, could continue to form, especially with aftershocks or rainfall.

People in landslide-affected areas were asked to keep away from all riverbeds in case there were any sudden releases of water.

Authorities were focusing attention on monitoring the larger dams that posed the highest risk to people, property and infrastructure.

Some of the new dams have already triggered evacuation warnings: last week, residents of Goose Bay were told 35 homes needed to be evacuated urgently because of an earthquake landslide upstream of the residential area.

Meanwhile, Dr Stefan Marks, a lecturer and researcher at Auckland University of Technology's Colab, has created new images showing the 7.8 quake and the aftershocks that have followed it.

Each dot on Marks' images reflects the earthquakes' magnitude, location and depth.

His research focuses on transforming data into fully immersive and interactive 3D imagery that can be used for multi-sensory visualisation, education, modelling, animation, rapid prototyping and much more.

He uses virtual reality equipment and GeoNet data.