My Google Map Blog

Tag: Colombia




Going Back in Time: The Armero Tragedy

by Timothy Whitehead on May.12, 2017, under 3D Models, Argentina, Australia, Brazil, California, Denmark, England, Germany, Google Earth News, Google Earth Tips, Google Sky, Google maps, Hawaii, Indonesia, Ireland, Italy, Japan, Kenya, Mexico, Natural Landmarks, Netherlands, Sightseeing, Street Views, USA

Last week we had a look at the Mocoa Landslide in Colombia. While doing research on that event, we came across a similar, but much bigger event known as the Armero Tragedy, also in Colombia, but it happened in 1985. Google Earth has yearly global mosaics going back to December 1984 (more about the exact date later) created from Landsat and Sentinel-2 imagery. In this particular location there is also imagery from 1970.

The Armero Tragedy was caused by the eruption of the Nevado del Ruiz volcano in Colombia. The eruption melted glaciers on the volcano, causing multiple landslides and mudslides, which later combined together through a narrow valley and then came out on top of the Colombian town of Armero, killing 20,000 of its almost 29,000 inhabitants. Interestingly, the location of Armero is showing in Google Earth as a town named ‘Armero tragedy’.

Looking through the global mosaics in Google Earth’s historical imagery, we can see the enormous mud flow from the tragedy even in the oldest mosaic dated December 1984. So it would appear the mosaic actually incorporates imagery from multiple years or is incorrectly dated, as the tragedy occurred on November 13, 1985. We obtained original Landsat imagery from the USGS’s Earth Explorer, including an image dated November 17th, 1985, just four days after the event, and another one from March 22nd, 1985 for comparison.

before
after

‘Before and After’ of the Armero Tragedy.


Armero today is just a grid of streets and foundations.

See the relevant parts of the Landsat images in Google Earth with this KML file.

The post Going Back in Time: The Armero Tragedy appeared first on Google Earth Blog.

Comments Off :, more...

The Mocoa Landslide in DigitalGlobe imagery

by Timothy Whitehead on May.05, 2017, under 3D Models, Argentina, Australia, Brazil, California, Denmark, England, Germany, Google Earth News, Google Earth Tips, Google Sky, Google maps, Hawaii, Indonesia, Ireland, Italy, Japan, Kenya, Mexico, Natural Landmarks, Netherlands, Sightseeing, Street Views, USA

According to Wikipedia, during the pre-dawn hours of 1 April 2017, locally heavy rain triggered flash flooding and landslides in the city of Mocoa, Putumayo, Colombia, killing at least 316 people, injuring 332, and leaving 103 others missing. Technically, the tragedy was not a landslide but rather a mud-flow triggered by many landslides. For some analysis of the cause of the tragedy see the Landslide Blog. It was predicted in 2014.

DigitalGlobe, as part of its Open Data program, has recently released satellite imagery of the location. Although we knew about the event soon after it happened, we had not expected to see any imagery as Mocoa is in a region that has near constant cloud cover, making it difficult to photograph.

DigitalGlobe provides the imagery divided up into squares of 1Gb files with no compression. So even a completely black square that is off the edge of the main image is a 1Gb download! There is a preview of the whole image, but we still ended up downloading almost all the squares to find the right ones as there are no previews of the individual squares.


Mocoa, Colombia, as seen in DigitalGlobe imagery.


Keep in mind that what we are seeing is the debris left behind from the flood. The actual flood waters probably covered some of the houses.

We didn’t download the ‘before’ images from DigitalGlobe so we haven’t done a ‘before and after’. The imagery in Google Earth is so old that such a comparison is not very informative as the town had expanded considerably since the last Google Earth image.

We have cropped and compressed the part of the imagery showing the town of Mocoa and created an image overlay for you to view in Google Earth.

The post The Mocoa Landslide in DigitalGlobe imagery appeared first on Google Earth Blog.

Comments Off :, , , more...






Looking for something?

Use the form below to search the site:

Still not finding what you're looking for? Drop a comment on a post or contact us so we can take care of it!

Visit our friends!

A few highly recommended friends...