Large eruption-triggered ocean-island landslide at Tenerife: Onshore record and long-term effects on hazardous pyroclastic dispersal

P Harris, M Branney, Michael Storey

    Publikation: Bidrag til tidsskriftTidsskriftartikelForskningpeer review

    Abstract

    An extensive debris-avalanche deposit has been discovered on Cañadas volcano, Tenerife (Canary Islands). The onshore component of the 733 ± 3 ka Abona landslide deposit exposes classic block facies and mixed facies across 90 km2. Three lines of evidence together show that the avalanche was triggered by an ignimbrite-forming explosive eruption: (1) the deposit is enclosed by phonolitic ignimbrites and is draped by a Plinian fallout layer, all within a single eruption unit; (2) it contains prismatic-jointed pumice blocks that were hot during landslide emplacement, indicated by chilled rims and breadcrust surfaces; (3) these blocks yield the same 40Ar/39Ar date as the associated ignimbrite and fall deposit. Landslide hummocks dammed surface water, forming ephemeral lakes perched on the volcano flank. Phonolite dome growth destabilized the southeast sector of a mid-Pleistocene Cañadas caldera wall, and created a major breach that affected the passage of destructive pyroclastic density currents on Tenerife for 0.5 m.y., showing that landslides can have enduring consequences for pyroclastic dispersal and hazards.
    OriginalsprogEngelsk
    TidsskriftGeology
    Vol/bind39
    Udgave nummer10
    Sider (fra-til)951-954
    ISSN0091-7613
    DOI
    StatusUdgivet - 2011

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