Some experiment with the Beirut explosion's aftermath

Microwave Toolbox Interferometry
#1

Hi, news of the explosion in Beirut are very sad, I hope nobody from this forum has suffered losses.

I was curious to see what of the aftermath of the explosion is observable from Sentinel-1, and I tried to replicate the displacement mapping tutorial with two images before and after the explosion. It seems that Sentinel-1B has already passed over the area.

The two images are S1B_IW_SLC__1SDV_20200730T034254_20200730T034321_022695_02B131_E8DD.zip and S1A_IW_SLC__1SDV_20200805T034334_20200805T034401_033766_03E9F9_52F6.zip. I get this filtered phase image for the Beirut area.

subset_0_of_S1A_IW_SLC__1SDV_20200805T034334_20200805T034401_033766_03E9F9_52F6_split_Orb_Stack_ifg_flt_Phase_ifg_IW1_VV_05Aug2020_30Jul2020
subset_0_of_S1A_IW_SLC__1SDV_20200805T034334_20200805T034401_033766_03E9F9_52F6_split_Orb_Stack_ifg_flt_Phase_ifg_IW1_VV_05Aug2020_30Jul20201365×823 1.9 MB

As a complete non-expert, I can make these remarks:

  • The port area has predictably gone completely incoherent. Beside creating a large crater and making a few buildings collapse, the explosion laid a lot of dust on the roads, probably completely altering their scattering properties.
  • In the rest of the city, it doesn’t seem that much has changed. I think that, though detected as a small earthquake by the USGS, an explosion happening outside the crust doesn’t really move the terrain level.
  • Still, some red dots appear not too far from the port. I don’t know what they are, maybe they correspond to particularly high buildings that might have resented a bit more by the explosion.
  • There is something going on near the airport too. I have no idea of what it is (and whether it is linked to the explosion).

I’d like to know if more expert users have thoughts to share here.

#2

thank you for sharing.

I cannot tell much about the plausibility of the patterns (especially the red circles), but if you want to get rid of these cross-like patterns, you can decrease the adaptive filter explonent in the Goldstein phase filtering to maybe 0.3. This is often observed in urban areas where artificial structures cause these phase artefacts.

#3

You may be interested in some work by a group at NASA looking at the same site with the same data: https://earthobservatory.nasa.gov/images/147098/scientists-map-beirut-blast-damage

Their results indicate that the damage detectable with SAR is localised to the region closest to the blast site, which would be the upper-middle part of your image, near the wavebreak.

#4

coherence loss in beirut

image
image1065×825 355 KB

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