TY - JOUR

T1 - Explosive-effusive volcanic eruption transitions caused by sintering

AU - Wadsworth, F.B.

AU - Llewellin, E.W.

AU - Vasseur, J.

AU - Gardner, J.E.

AU - Tuffen, H.

PY - 2020/9/23

Y1 - 2020/9/23

N2 - Silicic volcanic activity has long been framed as either violently explosive or gently effusive. However, recent observations demonstrate that explosive and effusive behavior can occur simultaneously. Here, we propose that rhyolitic magma feeding subaerial eruptions generally fragments during ascent through the upper crust and that effusive eruptions result from conduit blockage and sintering of the pyroclastic products of deeper cryptic fragmentation. Our proposal is supported by (i) rhyolitic lavas are volatile depleted; (ii) textural evidence supports a pyroclastic origin for effusive products; (iii) numerical models show that small ash particles ≲10-5 m can diffusively degas, stick, and sinter to low porosity, in the time available between fragmentation and the surface; and (iv) inferred ascent rates from both explosive and apparently effusive eruptions can overlap. Our model reconciles previously paradoxical observations and offers a new framework in which to evaluate physical, numerical, and geochemical models of Earth's most violent volcanic eruptions.

AB - Silicic volcanic activity has long been framed as either violently explosive or gently effusive. However, recent observations demonstrate that explosive and effusive behavior can occur simultaneously. Here, we propose that rhyolitic magma feeding subaerial eruptions generally fragments during ascent through the upper crust and that effusive eruptions result from conduit blockage and sintering of the pyroclastic products of deeper cryptic fragmentation. Our proposal is supported by (i) rhyolitic lavas are volatile depleted; (ii) textural evidence supports a pyroclastic origin for effusive products; (iii) numerical models show that small ash particles ≲10-5 m can diffusively degas, stick, and sinter to low porosity, in the time available between fragmentation and the surface; and (iv) inferred ascent rates from both explosive and apparently effusive eruptions can overlap. Our model reconciles previously paradoxical observations and offers a new framework in which to evaluate physical, numerical, and geochemical models of Earth's most violent volcanic eruptions.

KW - article

KW - ash

KW - feeding

KW - porosity

KW - volcano

U2 - 10.1126/sciadv.aba7940

DO - 10.1126/sciadv.aba7940

M3 - Journal article

VL - 6

JO - Science Advances

JF - Science Advances

SN - 2375-2548

IS - 39

M1 - eaba7940

ER -