Italy’s earthquake

As of this writing, Google has not updated ‘historical imagery’ for almost three months. Up until mid-June they had been updating it almost weekly. As a result, there have been a lot of events over the past few months that we know were captured by DigitalGlobe but we cannot access the imagery in Google Earth. One such event was the deadly earthquake that struck central Italy on August 24th, 2016.

Google has provided an image of the region from one of Terra Bella’s SkySat satellites. It can be viewed in Google Earth using this KML file. They SkySat satellites are not as high resolution as most Google Earth satellite imagery, but in this case, some of the affected regions in Italy do not have high resolution satellite imagery – all they have is SPOT imagery, which is lower resolution than the SkySat imagery. Despite the relatively low resolution, we can see some of the effects of the earthquake in the imagery.

Before image: CNES/Spot Image. After image: Google / Terra Bella.
Amatrice, Italy. 1: The location of most of the damaged buildings. 2 & 3: Tents set up after the disaster.

We also saw tents in Grisciano in the Terra Bella image.

Also worth looking at is the Copernicus Emergency Management Service. They gathered satellite imagery of the affected region almost immediately after the earthquake and within a day or two had arranged aerial imagery too. The results can be seen on this page. There are maps of the affected towns, including grading the amount of damage down to building level. For example, you can see the map for Amatrice in this PDF.

Sentinel-1A and Sentinel-1B are radar satellites that are particularly good at detecting changes in terrain. You can see deformation maps in this article that uses images from before and after the event to detect how much the ground had moved after the earthquake.