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New Zealand is currently experiencing one of its worst natural disasters since the Hawke's Bay earthquake in 1931. One factor that differs significantly between now and then, is the availability of satellites and space applications. While New Zealand has no satellites of its own, through international disaster charters, the first satellite images have been obtained, highlighting areas of damage.

The following images relate to the 6.3 magnitude Earthquake on 22 February 2011, centred near Lyttelton in the Christchurch region.

Digital Globe Images

Hitachi Solutions has published a GeoPDF (Japanese - view English translation) of a Digital Globe satellite image, showing the central Christchurch area.

Two PDF files have been produced, from satellite images taken on 24 February:

Here is a preview of the PDF files (Zoom in on the PDF files to see the full detail):

© Digital Globe / Hitachi Solutions, Ltd

Thank you very much to Mr Atsushi ONO, at the Disaster Management Support Systems Office (DMSSO) for JAXA for making us aware of these products.

Google Earth Satellite Images

We have managed to locate some GeoEye images taken on 23 February 2011, which have been overlayed in Google Earth. This is the first set of imagery of suitable resolution to view the building detail.

View in Google Earth

View in Google Earth
You can zoom in and pan around the images, which show Christchurch two days after the disaster. By unchecking the image layers, you can see the landscape before the earthquake.

This is also available in Google Maps - View in Google Maps.



ABC News, Australia appears to have some selected scenes from these images, in a nice before-and-after display.

First information products

Click the images for full-size view (Files are approximately 6MB each).

Disaster Extent Map - Flooding and Silt

Christchurch Centre, Acquired 23 February 2011. Annotated with known locations of damaged buildings.
Produced 25 February, 9pm.

This image/map shows areas of seismic induced flood traces (liquifaction traces) - highlighted in red, as observed in the satellite images.

Damage Assessment Map - Detail

Christchurch Centre, Acquired 23 February 2011. Annotated with known locations of damaged buildings.
Updated with more information overlays (25 February, 18:50)

This image/map shows locations of damaged buildings and other key locations around Christchurch.

View earlier damage assessment maps:


These satellite images were provided by the French space agency (CNES) under the UN Disaster Charter, at the request of the NZ Ministry of Civil Defence and Emergency Management.

A similar charter activation has been actioned via the Asia-Pacific Regional Space Agency's (APRSAF) Sentinel Asia disaster monitoring scheme.

Satellites and disaster management

The initial images show the strengths and weaknesses of the various satellite imagery: On one hand, satellite images give a birds-eye view of the landscape, providing a complete picture of the location. Comparison of pre- and post-disaster images can allow quick identification of affected areas. However these initial satellite images are essentially photographs, and so are obscured by dust, smoke, and cloud cover. Radar-based satellite sensors will be able to provide views through this cover, but these images are not available yet.

Several international or regional efforts exist to provide free satellite data in response to natural disasters (flooding, earthquakes, etc) and man-made disasters (oil spills, etc). To KiwiSpace' knowledge, New Zealand is not a formal member of these charters, but have been able to access them through through partner agencies and international goodwill. The disaster organisations not only provide the raw images, but also processing of the data – to help deliver meaningful information products, especially to nations who may not have this domestic capability.

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See our other Articles on the Christchurch Earthquake




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2 Comments

  1. Anonymous

    Hi Mark,

    Just had a look at the liquefaction damage map and it's not correct for my street. I live in Halberg Street in Dallington and the red area stops about where my house is. We had silt come in through the dining room doors and had to cut up the carpet, it's still solid under the deck outside and when my neighbour came over a few days after the quake she remarked that we were lucky still having some grass visible. I also have photos of the street which show that the liquefaction severely affected the street to the North and south of our property. Am happy to share the photos with you!

    Kind regards,

    Deborah

    1. Hi Deborah -

      Thanks for the feedback.

      The areas identified on the map, are calculations based on amount of reflectivity between comparison images, etc. So they will not be completely accurate.

      This highlights some of the challenges of satellite imagery – they are definitely not a replacement for 'ground truth'. They do help with broader analysis to identify worse affected areas, etc.

      Regards,
      Mark Mackay.