Instability of Hawaiian volcanoes: Chapter 4 in Characteristics of Hawaiian volcanoes

Professional Paper 1801- 4
By:  and 
Edited by: Michael P. PolandT. Jane Takahashi, and Claire M. Landowski

Links

Abstract

Hawaiian volcanoes build long rift zones and some of the largest volcanic edifices on Earth. For the active volcanoes on the Island of Hawai‘i, the growth of these rift zones is upward and seaward and occurs through a repetitive process of decades-long buildup of a magma-system head along the rift zones, followed by rapid large-scale displacement of the seaward flank in seconds to minutes. This large-scale flank movement, which may be rapid enough to generate a large earthquake and tsunami, always causes subsidence along the coast, opening of the rift zone, and collapse of the magma-system head. If magma continues to flow into the conduit and out into the rift system, then the cycle of growth and collapse begins again. This pattern characterizes currently active Kīlauea Volcano, where periods of upward and seaward growth along rift zones were punctuated by large (>10 m) and rapid flank displacements in 1823, 1868, 1924, and 1975. At the much larger Mauna Loa volcano, rapid flank movements have occurred only twice in the past 200 years, in 1868 and 1951.

All seaward flank movement occurs along a detachment fault, or décollement, that forms within the mixture of pelagic clays and volcaniclastic deposits on the old seafloor and pushes up a bench of debris along the distal margin of the flank. The offshore uplift that builds this bench is generated by décollement slip that terminates upward into the overburden along thrust faults. Finite strain and finite strength models for volcano growth on a low-friction décollement reproduce this bench structure, as well as much of the morphology and patterns of faulting observed on the actively growing volcanoes of Mauna Loa and Kīlauea. These models show how stress is stored within growing volcano flanks, but not how rapid, potentially seismic slip is triggered along their décollements. The imbalance of forces that triggers large, rapid seaward displacement of the flank after decades of creep may result either from driving forces that change rapidly, such as magma pressure gradients; from resisting forces that rapidly diminish with slip, such as those arising from coupling of pore pressure and dilatancy within décollement sediment; or, from some interplay between driving and resisting forces that produces flank motion. Our understanding of the processes of flank motion is limited by available data, though recent studies have increased our ability to quantitatively address flank instability and associated hazards.

Study Area

Additional publication details

Publication type Report
Publication Subtype USGS Numbered Series
Title Instability of Hawaiian volcanoes: Chapter 4 in Characteristics of Hawaiian volcanoes
Series title Professional Paper
Series number 1801
Chapter 4
DOI 10.3133/pp18014
Year Published 2014
Language English
Publisher U.S. Geological Survey
Publisher location Reston, VA
Contributing office(s) Volcano Science Center, Volcano Hazards Program
Description 28 p.
Larger Work Type Report
Larger Work Subtype USGS Numbered Series
Larger Work Title Characteristics of Hawaiian volcanoes (Professional Paper 1801)
First page 149
Last page 176
Country United States
State Hawaii
Online Only (Y/N) N
Additional Online Files (Y/N) N