Lago Riesco: a large debris flow in southern Chile

Over the weekend, on images appeared on Twitter of the aftermath of a large debris flow close to Lago Riesco in the Aysen area of southern Chile.  The scale of the event, which occurred on 11 March 2023, was impressive:-

AHORA ⚠️ Más fotografías del gran flujo en masa ocurrido hace breves instantes en Camino a Lago Riesco, km. 5, región de #Aysén.

📸 Créditos: Carlos Francisco Raimapo Miranda. pic.twitter.com/khvX3kS2Nf

— Red Geocientífica de Chile (@RedGeoChile) March 11, 2023

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AHORA ⚠️ Debido a las intensas precipitaciones con isoterma cero alta, se generó un gran flujo en masa en Camino a Lago Riesco, en el kilómetro 5, en la región de #Aysén. De momento, la ruta se encuentra cortada.

📹 Gentileza: Aysén Ahora. pic.twitter.com/VduBDcCg3w

— Red Geocientífica de Chile (@RedGeoChile) March 11, 2023

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This was triggered by a period of very heavy rainfall.  The Mop Aysen Facebook page has some details about the event, including this image:-

The aftermath of the large debris flow close to Lago Riesco in Chile on 11 March 2023. Image from the Mop Aysen Facebook page.  The image was supplied by Panoramica Informativa.

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The location of this event appears to be [-45.419, -72.632].  This is a Google Earth image of the site:-

Google Earth image of the site of the large debris flow close to Lago Riesco in Chile on 11 March 2023.

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This is an extremely cloudy area, so obtaining satellite imagery of the aftermath is difficult.  The debris flow appears to have originated in a deeply incised and intriguingly linear channel on the steep slopes above the road.  It is notable that there is a large amount of woody debris in the flow, which might imply that there has been a significant slope failure on the margin of the channel at some point.  I wonder also whether channel blockage, and then a sudden release, may have played a part here too.

Panoramic Informativa has a rather wonderful drone video of the site. Unfortunately, the vagaries of WordPress mean that I cannot embed it, but you should be able to view it here. The videographer has done an amazing job of flying a long way up the channel, although the source of the landslide is not clear.

The aftermath of the large debris flow close to Lago Riesco in Chile on 11 March 2023. Image from the Panoramica Informativa Facebook page.

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Note that the flow has crossed a fan deposit, suggesting that this is not the first large event to be generated by this channel.

Acknowledgement

Thanks to Luis Donoso for making me aware of this event.