Home > Research > Publications & Outputs > Morphological complexities and hazards during t...

Associated organisational unit

View graph of relations

Morphological complexities and hazards during the emplacement of channel-fed `a`ā lava flow fields: a study of the 2001 lower flow field on Etna

Research output: Contribution to Journal/MagazineJournal articlepeer-review

Published

Standard

Morphological complexities and hazards during the emplacement of channel-fed `a`ā lava flow fields: a study of the 2001 lower flow field on Etna. / Applegarth, Louisa Jane; Pinkerton, Harry; James, Michael et al.
In: Bulletin of Volcanology, Vol. 72, No. 6, 08.2010, p. 641-656.

Research output: Contribution to Journal/MagazineJournal articlepeer-review

Harvard

APA

Vancouver

Author

Bibtex

@article{362050c8777a47528aa26870ccc12ff1,
title = "Morphological complexities and hazards during the emplacement of channel-fed `a`ā lava flow fields: a study of the 2001 lower flow field on Etna",
abstract = "Long-lived basaltic eruptions often produce structurally complex, compound `a`ā flow fields. Here we reconstruct the development of a compound flow field emplaced during the 2001 eruption of Mt. Etna (Italy). Following an initial phase of cooling-limited advance, the reactivation of stationary flows by superposition of new units caused significant channel drainage. Later, blockages in the channel and effusion rate variations resulted in breaching events that produced two new major flow branches. We also examined small-scale, late-stage {\textquoteleft}squeeze-up{\textquoteright} extrusions that were widespread in the flow field. We classified these as {\textquoteleft}flows{\textquoteright}, {\textquoteleft}tumuli{\textquoteright} or {\textquoteleft}spines{\textquoteright} on the basis of their morphology, which depended on the rheology, extrusion rate and cooling history of the lava. Squeeze-up flows were produced when the lava was fluid enough to drain away from the source bocca, but fragmented to produce blade-like features that differed markedly from `a`ā clinker. As activity waned, increased cooling and degassing led to lava arriving at boccas with a higher yield strength. In many cases this was unable to flow after extrusion, and laterally extensive, near-vertical sheets of lava developed. These are considered to be exogenous forms of tumuli. In the highest yield strength cases, near-solid lava was extruded from the flow core as a result of ramping, forming spines. The morphology and location of the squeeze-ups provides insight into the flow rheology at the time of their formation. Because they represent the final stages of activity of the flow, they may also help to refine estimates of the most advanced rheological states in which lava can be considered to flow. Our observations suggest that real-time monitoring of compound flow field evolution may allow complex processes such as channel breaching and bocca formation to be forecast. In addition, documenting the occurrence and morphology of squeeze-ups may allow us to determine whether there is any risk of a stalled flow front being reactivated. This will therefore enhance our ability to track and assess hazard posed by lava flow emplacement.",
keywords = "Basaltic `a`ā , Channel-fed lava, Effusion rate , Squeeze-up , Tumuli , Etna",
author = "Applegarth, {Louisa Jane} and Harry Pinkerton and Michael James and Sonia Calvari",
year = "2010",
month = aug,
doi = "10.1007/s00445-010-0351-1",
language = "English",
volume = "72",
pages = "641--656",
journal = "Bulletin of Volcanology",
issn = "0258-8900",
publisher = "Springer-Verlag",
number = "6",

}

RIS

TY - JOUR

T1 - Morphological complexities and hazards during the emplacement of channel-fed `a`ā lava flow fields

T2 - a study of the 2001 lower flow field on Etna

AU - Applegarth, Louisa Jane

AU - Pinkerton, Harry

AU - James, Michael

AU - Calvari, Sonia

PY - 2010/8

Y1 - 2010/8

N2 - Long-lived basaltic eruptions often produce structurally complex, compound `a`ā flow fields. Here we reconstruct the development of a compound flow field emplaced during the 2001 eruption of Mt. Etna (Italy). Following an initial phase of cooling-limited advance, the reactivation of stationary flows by superposition of new units caused significant channel drainage. Later, blockages in the channel and effusion rate variations resulted in breaching events that produced two new major flow branches. We also examined small-scale, late-stage ‘squeeze-up’ extrusions that were widespread in the flow field. We classified these as ‘flows’, ‘tumuli’ or ‘spines’ on the basis of their morphology, which depended on the rheology, extrusion rate and cooling history of the lava. Squeeze-up flows were produced when the lava was fluid enough to drain away from the source bocca, but fragmented to produce blade-like features that differed markedly from `a`ā clinker. As activity waned, increased cooling and degassing led to lava arriving at boccas with a higher yield strength. In many cases this was unable to flow after extrusion, and laterally extensive, near-vertical sheets of lava developed. These are considered to be exogenous forms of tumuli. In the highest yield strength cases, near-solid lava was extruded from the flow core as a result of ramping, forming spines. The morphology and location of the squeeze-ups provides insight into the flow rheology at the time of their formation. Because they represent the final stages of activity of the flow, they may also help to refine estimates of the most advanced rheological states in which lava can be considered to flow. Our observations suggest that real-time monitoring of compound flow field evolution may allow complex processes such as channel breaching and bocca formation to be forecast. In addition, documenting the occurrence and morphology of squeeze-ups may allow us to determine whether there is any risk of a stalled flow front being reactivated. This will therefore enhance our ability to track and assess hazard posed by lava flow emplacement.

AB - Long-lived basaltic eruptions often produce structurally complex, compound `a`ā flow fields. Here we reconstruct the development of a compound flow field emplaced during the 2001 eruption of Mt. Etna (Italy). Following an initial phase of cooling-limited advance, the reactivation of stationary flows by superposition of new units caused significant channel drainage. Later, blockages in the channel and effusion rate variations resulted in breaching events that produced two new major flow branches. We also examined small-scale, late-stage ‘squeeze-up’ extrusions that were widespread in the flow field. We classified these as ‘flows’, ‘tumuli’ or ‘spines’ on the basis of their morphology, which depended on the rheology, extrusion rate and cooling history of the lava. Squeeze-up flows were produced when the lava was fluid enough to drain away from the source bocca, but fragmented to produce blade-like features that differed markedly from `a`ā clinker. As activity waned, increased cooling and degassing led to lava arriving at boccas with a higher yield strength. In many cases this was unable to flow after extrusion, and laterally extensive, near-vertical sheets of lava developed. These are considered to be exogenous forms of tumuli. In the highest yield strength cases, near-solid lava was extruded from the flow core as a result of ramping, forming spines. The morphology and location of the squeeze-ups provides insight into the flow rheology at the time of their formation. Because they represent the final stages of activity of the flow, they may also help to refine estimates of the most advanced rheological states in which lava can be considered to flow. Our observations suggest that real-time monitoring of compound flow field evolution may allow complex processes such as channel breaching and bocca formation to be forecast. In addition, documenting the occurrence and morphology of squeeze-ups may allow us to determine whether there is any risk of a stalled flow front being reactivated. This will therefore enhance our ability to track and assess hazard posed by lava flow emplacement.

KW - Basaltic `a`ā

KW - Channel-fed lava

KW - Effusion rate

KW - Squeeze-up

KW - Tumuli

KW - Etna

U2 - 10.1007/s00445-010-0351-1

DO - 10.1007/s00445-010-0351-1

M3 - Journal article

VL - 72

SP - 641

EP - 656

JO - Bulletin of Volcanology

JF - Bulletin of Volcanology

SN - 0258-8900

IS - 6

ER -