16 January 2018

Satellite images of the Montecito debris flows in California

Posted by Dave Petley

Satellite images of the Montecito debris flows in California

Last week significant debris flows struck the Montecito area of California.  At least 20 people were killed, with a further four people reported as being missing.  The highly mobile flows barreled down three major gullies, the Montecito, San Ysidro, and Romero creeks in the hills to the north of the community.  This area was severely burnt by the Thomas Fire in December.  The vulnerability of the area affected by the fire to landslides had been highlighted in advance.

Planet Labs have now imaged the area affected by the landslides, and have kindly made the imagery available to me.  Once again I am amazed at the quality of the images that they are able to collect.  This image, collected on 10th January, 2018, shows the area affected by the landslides:-

Montecito debris flows

Planet Labs image of the Montecito debris flows area

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Note the severely burnt and eroded area to the north of the town. and the obviously denuded hillsides that were the source of the flows.  The high resolution Planet Labs image below provides a perspective on the area affected by the flows themselves:-

Montecito debris flows

High resolution Planet Labs image of the Montecito debris flows

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The flow emerging from the gully is clear in the image once you look carefully.  The imagery shows the extraordinary trail of destruction left by the flows all the way from the mouth of the gully to the coast.  This is a more detailed image of the area close to the mouth of the gully:-

Montecito debris flows

Planet Labs image of the damage caused by the Montecito debris flows.

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The swathe of destruction caused by the flows is clear – in places it is even possible to see partially buried houses.  This damage continues to a greater or lesser extent all the way to the coast.  The image below shows the southern part of the town – note the inundation on the east-west highway:

Montecito debris flows

Planet Labs image of the southern part of the Montecito debris flows

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Reference

Planet Team (2017). Planet Application Program Interface: In Space for Life on Earth. San Francisco, CA. https://api.planet.com