Ropy pahoehoe

Surface folding of a viscous fluid

Jonathan H. Fink, Raymond Charles Fletcher

Research output: Contribution to journalArticle

95 Citations (Scopus)

Abstract

The regularly spaced surface structure observed on ropy pahoehoe basalt flows may be interpreted as folds which develop at the surface of a fluid whose viscosity decreases with depth. Folds form by the selective amplification of an irregular waviness in surface shape during shortening of the flow surface. The development of a regular fold arc length, predicted by folding theory, is reflected in the length scale of pahoehoe ropes. Pahoehoe fold arc lengths and the strength of the folding instability are determined by: (1) the ratio of the surface viscosity to the interior viscosity; (2) the thickness of the thermal boundary layer across which the viscosity changes; and (3) the ratio of the surface compressive stress to a stress related to the weight of the lava. The braided appearance of many ropy pahoehoe flows can be explained by a superposition of two episodes of folding.

Original languageEnglish (US)
Pages (from-to)151-170
Number of pages20
JournalJournal of Volcanology and Geothermal Research
Volume4
Issue number1-2
DOIs
StatePublished - Jan 1 1978

Fingerprint

pahoehoe
viscous fluids
folding
viscosity
Fluids
fluid
Viscosity
fold
arcs
thermal boundary layer
Compressive stress
Surface structure
lava
Amplification
amplification
Boundary layers
basalt
boundary layer
fluids

All Science Journal Classification (ASJC) codes

  • Geophysics
  • Geochemistry and Petrology

Cite this

Fink, Jonathan H. ; Fletcher, Raymond Charles. / Ropy pahoehoe : Surface folding of a viscous fluid. In: Journal of Volcanology and Geothermal Research. 1978 ; Vol. 4, No. 1-2. pp. 151-170.
@article{0d22144c34de4223ba8324028f56d5b5,
title = "Ropy pahoehoe: Surface folding of a viscous fluid",
abstract = "The regularly spaced surface structure observed on ropy pahoehoe basalt flows may be interpreted as folds which develop at the surface of a fluid whose viscosity decreases with depth. Folds form by the selective amplification of an irregular waviness in surface shape during shortening of the flow surface. The development of a regular fold arc length, predicted by folding theory, is reflected in the length scale of pahoehoe ropes. Pahoehoe fold arc lengths and the strength of the folding instability are determined by: (1) the ratio of the surface viscosity to the interior viscosity; (2) the thickness of the thermal boundary layer across which the viscosity changes; and (3) the ratio of the surface compressive stress to a stress related to the weight of the lava. The braided appearance of many ropy pahoehoe flows can be explained by a superposition of two episodes of folding.",
author = "Fink, {Jonathan H.} and Fletcher, {Raymond Charles}",
year = "1978",
month = "1",
day = "1",
doi = "10.1016/0377-0273(78)90034-3",
language = "English (US)",
volume = "4",
pages = "151--170",
journal = "Journal of Volcanology and Geothermal Research",
issn = "0377-0273",
publisher = "Elsevier",
number = "1-2",

}

Ropy pahoehoe : Surface folding of a viscous fluid. / Fink, Jonathan H.; Fletcher, Raymond Charles.

In: Journal of Volcanology and Geothermal Research, Vol. 4, No. 1-2, 01.01.1978, p. 151-170.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Ropy pahoehoe

T2 - Surface folding of a viscous fluid

AU - Fink, Jonathan H.

AU - Fletcher, Raymond Charles

PY - 1978/1/1

Y1 - 1978/1/1

N2 - The regularly spaced surface structure observed on ropy pahoehoe basalt flows may be interpreted as folds which develop at the surface of a fluid whose viscosity decreases with depth. Folds form by the selective amplification of an irregular waviness in surface shape during shortening of the flow surface. The development of a regular fold arc length, predicted by folding theory, is reflected in the length scale of pahoehoe ropes. Pahoehoe fold arc lengths and the strength of the folding instability are determined by: (1) the ratio of the surface viscosity to the interior viscosity; (2) the thickness of the thermal boundary layer across which the viscosity changes; and (3) the ratio of the surface compressive stress to a stress related to the weight of the lava. The braided appearance of many ropy pahoehoe flows can be explained by a superposition of two episodes of folding.

AB - The regularly spaced surface structure observed on ropy pahoehoe basalt flows may be interpreted as folds which develop at the surface of a fluid whose viscosity decreases with depth. Folds form by the selective amplification of an irregular waviness in surface shape during shortening of the flow surface. The development of a regular fold arc length, predicted by folding theory, is reflected in the length scale of pahoehoe ropes. Pahoehoe fold arc lengths and the strength of the folding instability are determined by: (1) the ratio of the surface viscosity to the interior viscosity; (2) the thickness of the thermal boundary layer across which the viscosity changes; and (3) the ratio of the surface compressive stress to a stress related to the weight of the lava. The braided appearance of many ropy pahoehoe flows can be explained by a superposition of two episodes of folding.

UR - http://www.scopus.com/inward/record.url?scp=0000022816&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0000022816&partnerID=8YFLogxK

U2 - 10.1016/0377-0273(78)90034-3

DO - 10.1016/0377-0273(78)90034-3

M3 - Article

VL - 4

SP - 151

EP - 170

JO - Journal of Volcanology and Geothermal Research

JF - Journal of Volcanology and Geothermal Research

SN - 0377-0273

IS - 1-2

ER -