Scientists Use ENVI to Determine Damage Extents in Earthquake Zones
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Customer Challenge
Earthquakes can cause extreme damage, not only to personal property, but to natural landscapes and infrastructures. Identifying the scope and amount of dame caused by an earthquake is vital for many reason, including disaster response and aid. The identification of damage due to large earthquakes is vital to grasping the level and extension of the hard-hit areas. Researcher Miguel Estrada needed a way to easily and quickly create visualizations and assess the amount and scope of damages.
Solution Achieved
In the event of large natural disasters, like a destructive earthquake, a fast assessment of the damaged areas is required to send off rescue teams. The identification of damage from a large area gives essential information that authorities can use to plan rescue procedures as well as to draw a general idea of the magnitude of the damage. Using remotely sensed images from satellite data both before and after a natural disaster, Estrada and fellow scientists Masashi Matsuoka and Fumio Ymazaki used ENVI® to compare the ratio between different bands of the pre and post event images to detect damage.
To assess the damage using the images, the team based their work off of the general premise that changes in land cover result in changes in radiance values, and changes in radiance due to land cover change are large with respect to radiance changes caused by other factors such as differences in atmospheric condition, differences in soil moisture and differences in sun angles. Using these premises, they were able produce change detected images using the images spectral information. These processed images can be easily compared to satellite images taken before the event, and the land damaged is clearly visible. In addition, using the image's spectral information allows them to detect the type of landcover in question, information that is useful when determining dollar value of loss and recovery plans.
This type of research is extremely valuable for the government and other organizations who assist in post-catastrophe management. By using advanced spectral processing tools included in ENVI, the Estrada team was able to add a valuable asset to the recovery tools used after a disaster.
Key Benefits
- Using ENVI, they can now compare the ratio between different bands of the pre and post event images to detect earthquake damage.
- Without remote sensing and ENVI, there would be considerably more, expensive field work involved.
- ENVI's built-in change detection routines were essential in comparing pre- and post-earthquake images.