Post-earthquake landslide distribution assessment using Sentinel-1 and -2 data: example of 2016 Mw 7,8 earthquake in New Zealand

Post-earthquake analysis using radar interferometry has become a standard procedure for assessing earthquakes with significant damages. Sentinel-1 satellite provides 6-day revisiting time, Sentinel-2 data has 5-day revisiting time with the same viewing angle which can enable detecting changes in surface/land-cover after major seismic event. Using Sentinel-2 alongside with Sentinel-1 could bring new benefits when gathering spatial information of post seismic event. In our study we focused on analyzing major earthquake, which occurred on 14 November 2016 with 7,8 magnitude near city of Kaikoura, New Zealand, using both Sentinel-1 radar images and Sentinel-2 optical data. Hundreds of landslides were reported as a result of this earthquake. In addition, substantial land uplift was detected in some parts of the sea shore. Differential interferometry allowed us to estimate earthquake strength by analyzing the distribution of absolute vertical displacement values. Sentinel-2 pre- and post-earthquake images were used in order to assess land-cover changes and automatically detect landslides, which occurred after the earthquake. Linking DInSAR results with Sentinel-2 change detection analysis helped us to get a more complex perspective on the earthquake impact, to create landslide susceptibility maps and subsequently develop workflows for quick post-event analysis.