GRSG 34th Conference 2023

Title: Applications of a continuously updated national InSAR map – New Zealand

Author: Nathan Magnall

Abstract:

SatSense alongside GNS Science have generated a continuously updated, national, InSAR dataset for the whole of New Zealand. The result is generated from all of the available Sentinel-1 SAR imagery acquired across New Zealand since 2015. The presentation will highlight the application of this dataset for monitoring natural hazards, such as ground movement associated with the Alpine Fault system, and post-seismic deformation due to the 2016 Kaikoura earthquake. At Kaikoura we demonstrate complex fault movements and postseismic deformation which persisted into 2019.

The availability of a nationwide InSAR dataset means that the data is available to a wide array of end-users, and can be practically used at a property level. An example of this is the use of the InSAR data for landslide stability assessments following Cyclone Gabrielle, which triggered a large number of landslides on the North Island, and had a particular impact on coastal and clifftop properties. In this case, not only do we demonstrate the suitability of the dataset for post-event analysis, but we also show how such tools could be used to evaluate those properties most at risk based on past movement.

As well as highlighting the potential applications of this dataset, the presentation will outline some of the practical challenges of processing such a large InSAR dataset and the unique challenges posed by a tectonically active region such as New Zealand. Finally, we will discuss the difficulty of processing large rural areas due to poor coherence and biases that can enter the dataset.

SatSense alongside GNS Science have generated a continuously updated, national, InSAR dataset for the whole of New Zealand. The result is generated from all of the available Sentinel-1 SAR imagery acquired across New Zealand since 2015.
The presentation will highlight the application of this dataset for monitoring natural hazards, such as ground movement associated with the Alpine Fault system, and post-seismic deformation due to the 2016 Kaikoura earthquake. At Kaikoura we demonstrate complex fault movements and postseismic deformation which persisted into 2019.

The availability of a nationwide InSAR dataset means that the data is available to a wide array of end-users, and can be practically used at a property level. An example of this is the use of the InSAR data for landslide stability assessments following Cyclone Gabrielle, which triggered a large number of landslides on the North Island, and had a particular impact on coastal and clifftop properties. In this case, not only do we demonstrate the suitability of the dataset for post-event analysis, but we also show how such tools could be used to evaluate those properties most at risk based on past movement.

As well as highlighting the potential applications of this dataset, the presentation will outline some of the practical challenges of processing such a large InSAR dataset and the unique challenges posed by a tectonically active region such as New Zealand. Finally, we will discuss the difficulty of processing large rural areas due to poor coherence and biases that can enter the dataset.