<p>It is a differential InSAR image that shows wrapped phase in radians which is a measure of the change in range (or distance) between the ground surface and a (more or less) fixed point in space from which the radar images were acquired (keep in mind that two SAR images are required to create an interferogram). To get the actual range change you have to unwrap the interferogram.</p>

<p>You can think of the fringes as contour lines. Areas where spacing between the fringes is tight, represent areas with high deformation, e.g., near the fault. The wavelength of the radar determines the fringe spacing. </p>

<p>A better looking interferogram for the Nepal earthquake is at <a href="http://topex.ucsd.edu/nepal/" rel="noreferrer">http://topex.ucsd.edu/nepal/</a> (made using SAR data acquired by the L-band ALOS-2 satellite operated by the Japanese Space Agency, JAXA).</p>

CC BY-SA 3.0
2017-05-05T03:25:48.793Z
2017-05-05T03:25:48.793Z
stali
<p>Here is a screenshot of coseismic interferometry measurements of the 2015 Nepal earthquake. What does it mean?</p>

<p>The star is the epicenter of the earthquake. The screenshot was taken from <a href="https://unosat.maps.arcgis.com/apps/webappviewer/index.html?id=b9f9da798f364cd6a6e68fc20f5475eb" rel="noreferrer">the UNOSAT live crisis map</a>.</p>

<p><a href="https://i.sstatic.net/XIp8M.png" rel="noreferrer"><img src="https://i.sstatic.net/XIp8M.png" alt="enter image description here"></a></p>

<p><a href="https://i.sstatic.net/bJbp6.jpg" rel="noreferrer"><img src="https://i.sstatic.net/bJbp6.jpg" alt="enter image description here"></a></p>

CC BY-SA 3.0
2017-05-05T16:10:17.633Z
Seismic interferometry is different from InSAR. The image above shows the coseismic deformation field as seen by InSAR. For the former, see https://inside.mines.edu/~rsnieder/Wapenaar_tutorial1_10.pdf
stali
<seismology><earthquakes>
How to interpret seismic interferometry data?
Matt Kleinsmith
# How to interpret seismic interferometry data?

(Asked by: username_0 on 2017-05-04)

Here is a screenshot of coseismic interferometry measurements of the 2015 Nepal earthquake. What does it mean?

The star is the epicenter of the earthquake. The screenshot was taken from [the UNOSAT live crisis map](https://unosat.maps.arcgis.com/apps/webappviewer/index.html?id=b9f9da798f364cd6a6e68fc20f5475eb).

[![enter image description here](https://i.sstatic.net/XIp8M.png)](https://i.sstatic.net/XIp8M.png)

[![enter image description here](https://i.sstatic.net/bJbp6.jpg)](https://i.sstatic.net/bJbp6.jpg)

**Tags:** seismology, earthquakes

> **Comments:**
> **username_1**: Seismic interferometry is different from InSAR. The image above shows the coseismic deformation field as seen by InSAR. For the former, see https://inside.mines.edu/~rsnieder/Wapenaar_tutorial1_10.pdf  

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## 1 answers

### Answer by username_1 on 2017-05-05. Score: 6 | Accepted answer

It is a differential InSAR image that shows wrapped phase in radians which is a measure of the change in range (or distance) between the ground surface and a (more or less) fixed point in space from which the radar images were acquired (keep in mind that two SAR images are required to create an interferogram). To get the actual range change you have to unwrap the interferogram.

You can think of the fringes as contour lines. Areas where spacing between the fringes is tight, represent areas with high deformation, e.g., near the fault. The wavelength of the radar determines the fringe spacing.

A better looking interferogram for the Nepal earthquake is at <http://topex.ucsd.edu/nepal/> (made using SAR data acquired by the L-band ALOS-2 satellite operated by the Japanese Space Agency, JAXA).


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