Bulletin of Volcanology

, Volume 49, Issue 2, pp 509–514 | Cite as

High velocity debris avalanche at Lastarria volcano in the north Chilean Andes

  • José Antonio Naranjo
  • Peter Francis


A pre-historic collapse of the southeast flank of Lastarria volcano (∼ 5700 m) in the north Chilean Andes (25° 10′ S), produced a fluidized volcanic debris avalanche whose morphology and surface structures are exceptionally well preserved. The avalanche travelled to the east-south-east, covering an area of 9.3 km2, and came to rest after climbing and over-riding a 125 m high older scoria cone. The 0.091 km3 avalanche has an apparent coefficient of friction (H/L) of 0.15 and an excessive travel distance index (Le) of 5.1 km, indicating high emplacement velocity, perhaps of the order of 80 m s−1. An important cause of the high mobility may have been the predominance of low-density, poorly cohesive scoriaceous and pumiceous layers in the source region. The flow may have had properties similar to those of a small ignimbrite.


Surface Structure Source Region High Mobility Sedimentology Travel Distance 
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Copyright information

© Springer-Verlag 1987

Authors and Affiliations

  • José Antonio Naranjo
    • 1
  • Peter Francis
    • 2
  1. 1.Servicio Nacional de Geología y MineríaSantiagoChile
  2. 2.Lunar and Planetary InstituteHoustonUSA

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