Google Earth Blog

The amazing things about Google Earth


tornado

Wikipedia data for US Tornadoes in Google Earth

Wikipedia has lists of notable tornadoes and tornado outbreaks worldwide for each year. For example, here is the list for 2016. There are also more detailed lists, such as this one for US Tornadoes from January to March 2016. The detailed lists give geographic coordinates and Enhanced Fujita Rating (EF rating).

We thought it would be interesting to see the locations in Google Earth. So, we imported the data for US tornadoes from Wikipedia going back to 2009. The pages for years prior to 2009 are organised differently so we could not easily import the data. We then used a variation of the tool we created earlier this year to check whether there is relevant imagery. This can take quite a long time, so we only did it for the stronger tornadoes – those with an EF rating of 2 or greater.

To see the results download this KML file. We provide the data either sorted by EF rating or by year. For the placemarks sorted by EF rating and EF rating 2 or greater, we have used a donut icon if there is imagery available within six months after the event.

Wikipedia states that the data comes from the US National Weather Service. The data does not show the paths of the tornadoes and there are often multiple placemarks for a given tornado. We also found the placemarks are not very accurate.

For examples of actual Google Earth imagery of the devastation caused by tornadoes see these posts.

The Jiangsu tornado

Although Google has neglected to update ‘historical imagery’ in Google Earth since early June, they have been adding fresh imagery, and when it is reasonably good quality, it goes into the default layer and we can see it. One such instance is a region in Jiangsu Province, China which was struck by a deadly tornado on June 23, 2016. According to Wikipedia, the tornado killed at least 99 people and injured 846 others (152 critically).

We found a number of articles showing various photos of the destruction, such as here, here, here and here. But, actually locating the event proved more difficult. We first mapped out the area that had new imagery and started searching through it for signs of damaged buildings, but with an area of nearly 4,000 square kilometres we were not successful. We did find a raised railway under construction, and a long trail of destroyed houses that turned out to be planned road construction. The articles either mention major nearby cities or small villages that aren’t marked on the map and couldn’t be found through search. Eventually we found mention of “Danping Village of Chenliang Township” and we were able to find Chenliang. From there, the path of destruction was easy to trace over a distance of around 30 km.

To see the path of the tornado in Google Earth download this KML file.

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Although the latest imagery is not very high quality, near total destruction of houses all along the path of the tornado is clear, especially when comparing it with older imagery.

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Some damaged factories.

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A factory roof ripped to shreds.

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See a higher resolution aerial image of this factory in this article

Google Earth Imagery Update: The Dallas, Texas Tornados

Google has recently pushed out another imagery update. Below we show approximate maps of where the new imagery from April, May and June can be found. There is almost certainly older imagery too, but it is harder to find.


June imagery.


May imagery. Red: Recently added imagery. Blue: Imagery as of June 12th.


April imagery. Red: Recently added imagery. Blue: Imagery as of June 12th.

To find the locations in Google Earth download this KML file.

As you can see above the new April imagery is almost exclusively aerial imagery, mostly of the US and a bit of Japan. Clearly aerial imagery takes a bit longer to process than satellite imagery. Strangely we have not yet seen any aerial imagery of Europe this year and very little satellite imagery.
[Correction: There are a few small patches of aerial imagery. ]

On December 26, 2015, there was an outbreak of at least 32 tornados, many of which were in the Dallas, Texas area. There is now some aerial imagery captured on April 28th, 2016, five months after the disaster. Nevertheless, the destruction is still very much in evidence, with the tornado scar over the Garland/Rowlett area visible from quite a high altitude. We have identified the tracks of the three strongest tornados.

We have in the past looked at low resolution imagery of the Garland/Rowlett area using both Landsat imagery and Sentinel imagery, but although we could clearly see the tornado scar, we could not see damage to individual houses.

Below are some ‘before and after’ comparisons. Drag the dividers left and right to compare the imagery.

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The above are all from the Garland/Rowlett tornadowhich was the strongest, but we show only a tiny fraction of the damage caused. Be sure to check out the imagery in Google Earth with this KML file as a guide. There is quite a lot of new construction in the area so when looking for damage be sure to compare with historical imagery as a house under construction looks remarkably similar to a severely damaged house.

Google Earth Imagery Update: LaPlace tornado

Google has recently pushed out another imagery update. We have mapped out the approximate locations of imagery for March, April and May, 2016. The last update we did maps for was this one. There was a minor update since then, but we did not generate maps other than identifying that there was only one image from May at the time and it was of the Fort McMurray wildfire.


May imagery


March imagery. Red:Recently added imagery. Blue:imagery as of May 10th.


April imagery. Red:Recently added imagery. Blue:imagery as of May 10th.

To view the outlines in Google Earth download this KML file.

On February 23rd, 2016, a tornado struck LaPlace, Louisiana. It was one of an outbreak of 60 tornadoes that struck over two days. It was a relatively mild tornado measuring EF2. The imagery is from April 7th, 2016, so more than a month after the tornado struck.


The path of the tornado. It didn’t leave much of a track visible from this altitude.


Zoom in a bit and notice the blue rooftops marking out that path the tornado took!


Most of the damage seems to have been at least temporarily repairable with blue roof tarpaulins. However, some completely destroyed houses can be seen.

Do any of our readers know why blue is the preferred colour for roof repair tarpaulins?

Be sure to explore it in Google Earth with this KML file.

Sentinel vs Landsat imagery

Yesterday we had a look at Snapsat, a useful website for obtaining Landsat imagery. The location we chose was Dallas, Texas and a track made by a tornado in December last year.

We thought it would be interesting to compare the Landsat imagery with the European equivalent – Sentinel imagery.

Landsat 8 captures colour images at 30 m per pixel, but also captures has a panchromatic band at 15 m per pixel, which can be combined (using a process known as pansharpening) with the colour bands to essentially achieve close to 15 m per pixel resolution. Sentinel 2A, on the other hand, captures images in colour at 10 m per pixel and does not use pansharpening. So the Sentinel imagery should be slightly better quality and we found this was indeed the case.

We are still learning the best ways to process imagery and neither image has been processed ideally.

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Landsat 8 imagery vs Sentinel 2A imagery.
Images courtesy of USGS/NASA Landsat and Copernicus Sentinel data 2016.

To see the images in Google Earth download this KML file.