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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
Article

Abstract

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.

Keywords

Surface Structure Source Region High Mobility Sedimentology Travel Distance 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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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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