Article
Geosciences, Multidisciplinary
Walter A. Sullivan, Emma J. O'Hara
Summary: This study uses various data to determine the deformation mechanisms and rheology of granite-derived fault rocks in the Kellyland fault zone. Deformation in this zone occurred during cooling and can be characterized by different types of rocks and their corresponding deformation mechanisms.
GEOLOGICAL MAGAZINE
(2022)
Article
Geochemistry & Geophysics
Erik M. Young, Christie D. Rowe, James D. Kirkpatrick
Summary: Crustal shear zones generate earthquakes, but their prediction is currently unpredictable. Studying the architecture of fault zones can reveal the controls on fault rupture, locking, and reloading, which influence the spatial and temporal patterns of earthquakes. The Pofadder Shear Zone in South Africa provides insights into ancient earthquake structures. A high-resolution geological map of the shear zone core mylonite zone was made, revealing layers of black ultramylonite and their relation to ancient earthquake rupture surfaces. The geometry of lithologic interfaces affected earthquake rupture paths.
Article
Geochemistry & Geophysics
F. Paglialunga, F. Passelegue, S. Latour, A. Gounon, M. Violay
Summary: Fluids in the Earth's crust affect the stability and dynamics of faults, and viscous fluids have been found to play a significant role in fault reactivation and earthquake ruptures. In experiments using analogue material, it was discovered that the presence of viscous lubricants along faults reduces frictional resistance, increases nucleation length, and decreases fracture energy. Furthermore, the higher the viscosity of the fluids, the greater the reduction in frictional strength and increase in nucleation length.
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(2023)
Article
Geochemistry & Geophysics
Sejin Jung, Ji-Hoon Kang, Youngwoo Kil, Haemyeong Jung
Summary: The 5.5 magnitude earthquake in Pohang, South Korea in 2017 was an example of one of the largest triggered earthquakes at an enhanced geothermal system (EGS) site. The faults that ruptured in Pohang were not initially detected, but further study of fault rocks at the site revealed features indicative of fault gouge or breccia. Additionally, evidence of frictional melting during coseismic slip suggests a prior seismic event at the Pohang EGS site.
Article
Geochemistry & Geophysics
Francesco Lazari, Angela Castagna, Stefan Nielsen, Ashley Griffith, Giorgio Pennacchioni, Rodrigo Gomila, Phil Resor, Chiara Cornelio, Giulio Di Toro
Summary: The frictional power per unit area Q played a crucial role in controlling earthquake rupture nucleation, propagation, and arrest. However, determining Q using geophysical methods is challenging. In this study, we estimated Q dissipated on a fault patch exhumed from 7-9 km depth by combining theoretical models, experimental data, and geological constraints. Our findings suggest that the grain-scale roughness of the boundary between frictional melt and host rock decreases with increasing Q. The estimated Q values range from 4-60 MW m-2, which are at the lower end of previous estimates.(c) 2023 Elsevier B.V. All rights reserved.
EARTH AND PLANETARY SCIENCE LETTERS
(2023)
Article
Engineering, Multidisciplinary
Richard M. Christensen
Summary: The transition from ductile to brittle behavior is determined to occur at specific values of certain material properties, with a strong relationship found with the elements of the Periodic Table, particularly iron. These findings extend beyond elemental materials and have significant implications for understanding the elastic and failure properties of materials. These developments build upon previous empirical observations from Pugh [7] and provide a broader insight into material behavior.
INTERNATIONAL JOURNAL OF ENGINEERING SCIENCE
(2021)
Article
Geochemistry & Geophysics
L. R. Campbell, L. Menegon
Summary: This study examines the microstructures of earthquake fault zones in the lower crust of Lofoten, Norway, and reveals that high stress loading (up to GPa magnitude) can occur in the dry lower crust and be preserved in the microstructure of fault rocks.
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(2022)
Article
Physics, Fluids & Plasmas
J. S. Langer
Summary: This paper attempts to construct a first-principles theory of the fracture toughness of crystalline solids based on the thermodynamic dislocation theory. The analysis results show that the theory's predictions quantitatively agree with experimental data, including both brittle and ductile fracture under various conditions.
Article
Multidisciplinary Sciences
Yan Lu, Yu-Heng Zhang, En Ma, Wei-Zhong Han
Summary: Body-centered cubic metals exhibit a ductile-to-brittle transition at a critical temperature, controlled by the ratio of screw dislocation velocity to edge dislocation velocity. A physical model shows the importance of coordinated movement of screw and edge dislocation segments for sustaining dislocation multiplication. High relative mobility is crucial for the transition of dislocation sources from disposable to regeneratable ones.
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2021)
Article
Geochemistry & Geophysics
Yao WenMing, Zhou YongSheng, Zhang Lei, Ma Xi, Dai WenHao
Summary: This study conducted frictional experiments on pseudotachylyte gouges under both hydrothermal and dry conditions. The results showed that the friction coefficient of pseudotachylyte gouges increased with increasing temperature and was lower in dry samples compared to hydrothermal conditions. The slip stability of pseudotachylyte gouges exhibited velocity strengthening at lower temperatures and velocity weakening at higher temperatures. Loading rate also affected the stability of pseudotachylyte gouges. The presence of pseudotachylyte could increase the possibility of earthquake nucleation and promote the propagation of co-seismic dynamic rupture.
CHINESE JOURNAL OF GEOPHYSICS-CHINESE EDITION
(2022)
Article
Geochemistry & Geophysics
Masaaki Obata, T. Mashimo, J. Ando, L. Chen, N. Kawai, Xun Liu, T. Yamamoto
Summary: Two kinds of shock compression experiments were conducted to study seismo-mechanochemical processes in forsteritic olivine. The experiments showed the generation of shear planes and local melting within a narrow zone along the shear plane. Microstructural observations revealed the comminution of olivine into nano-sized particles and partial melting. The power generated by friction was large enough to cause melting, occurring in a time scale <0.6 microseconds.
PHYSICS OF THE EARTH AND PLANETARY INTERIORS
(2023)
Article
Geosciences, Multidisciplinary
Wenhao Dai, Yongsheng Zhou, Xi Ma
Summary: This study analyzed the microstructures of samples collected from the Red River fault in southwest of China, revealing transient creep behavior in the brittle-plastic transition zone during the seismic cycle. The authors proposed an oscillation deformation model to explain this phenomenon.
FRONTIERS IN EARTH SCIENCE
(2022)
Article
Multidisciplinary Sciences
Dawang Zhang, James M. Campbell, Jon A. Eriksen, Eirik G. Flekkoy, Knut Jorgen Maloy, Christopher W. MacMinn, Bjornar Sandnes
Summary: Multiphase flows involving granular materials often exhibit complex pattern formation due to simultaneous mechanical and hydrodynamic interactions. In this study, the authors investigate the interplay between granular bulldozing and the stabilizing effect of viscous pressure gradients in fluid invasion. They observe a transition from single to multiple fingers growth as viscous forces increase in a scenario where aqueous solutions are injected into dry, hydrophobic grains. The patterns are further compacted by internal viscous pressure gradients, leading to a stabilized front of frictional fingers advancing as a radial spoke pattern. Fingering patterns form spontaneously when a non-wetting viscous liquid displaces a dry granular mixture in a confined flow cell, and this study reveals how the resulting patterns are regulated by the balance between viscous, capillary, and frictional forces.
NATURE COMMUNICATIONS
(2023)
Article
Geosciences, Multidisciplinary
Hiroyuki Noda
Summary: This study investigates the interaction between shear and bulk plastic flow in shear zones, and finds that the inclination of slip planes leads to weakening. It also suggests that previous models may overestimate the strength of slip elements in the brittle-plastic transition.
JOURNAL OF STRUCTURAL GEOLOGY
(2021)
Article
Geology
Margaret L. Odlum, Drew A. Levy, Daniel F. Stockli, Lisa D. Stockli, Joel W. DesOrmeau
Summary: This study used apatite petrochronology to investigate the timing and processes of ductile deformation and metasomatism in a shear zone in the Pyrenees. The results show that crystal plastic deformation and fluid interactions can significantly alter the isotopic signatures of apatite, highlighting the importance of single-grain apatite petrochronology for dating and characterizing recent deformation and fluid events that may not be captured by higher-temperature chronometers.
Article
Engineering, Mechanical
Alden C. Cook, Senthil S. Vel, Scott E. Johnson
INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES
(2018)
Article
Geosciences, Multidisciplinary
David Okaya, Senthil S. Vel, Won Joon Song, Scott E. Johnson
Article
Geography, Physical
Ian R. Lee, Robert L. Hawley, Steven Bernsen, Seth W. Campbell, David Clemens-Sewall, Christopher C. Gerbi, Kate Hruby
JOURNAL OF GLACIOLOGY
(2020)
Article
Geochemistry & Geophysics
Bo Ra Song, Scott E. Johnson, Won Joon Song, Cristopher C. Gerbi, Martin G. Yates
EARTH AND PLANETARY SCIENCE LETTERS
(2020)
Article
Geography, Physical
Kate Hruby, Christopher Gerbi, Peter Koons, Seth Campbell, Carlos Martin, Robert Hawley
JOURNAL OF GLACIOLOGY
(2020)
Article
Geosciences, Multidisciplinary
Won Joon Song, Scott E. Johnson, Christopher C. Gerbi
JOURNAL OF STRUCTURAL GEOLOGY
(2020)
Article
Geochemistry & Geophysics
Scott E. Johnson, Won Joon Song, Alden C. Cook, Senthil S. Vel, Christopher C. Gerbi
Summary: The alpha <-> beta phase transition in quartz can greatly affect the stress, mechanical properties, metamorphism, and rheology of crustal rocks, potentially leading to microcracking, brittle failure, and recrystallization. The elastic stresses arising from the transition may exceed the brittle strengths of rocks and minerals, particularly in environments experiencing rapid geological changes, impacting seismic activities.
EARTH AND PLANETARY SCIENCE LETTERS
(2021)
Article
Geochemistry & Geophysics
Erik K. Anderson, Won Joon Song, Scott E. Johnson, Alicia M. Cruz-Uribe
Summary: The optical measurements of kinked micas along the Sandhill Corner shear zone suggest that their geometric properties are statistically different from regional deformed and metamorphosed micas. The findings indicate that mica kink bands could serve as a useful indicator of dynamic loading and paleoseismicity in the rock record.
EARTH AND PLANETARY SCIENCE LETTERS
(2021)
Article
Geochemistry & Geophysics
Scott E. Johnson, Won Joon Song, Senthil S. Vel, Bo Ra Song, Christopher C. Gerbi
Summary: The research estimated surface-area energy density in the dynamic damage zone of a deeply exhumed strike-slip fault/shear zone using garnet fragment size data. The results suggest that surface-energy generation is a nonnegligible component of the earthquake energy budget.
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(2021)
Article
Geochemistry & Geophysics
Bo Ra Song, Won Joon Song, Scott E. Johnson, Christopher C. Gerbi, Senthil S. Vel
Summary: Mature faults often separate rocks with different elastic properties, and analyzing the elastic contrast of bimaterial faults is important for understanding earthquake physics and related hazard potential.
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(2022)
Article
Environmental Sciences
Kimberley R. Miner, Seth Campbell, Christopher Gerbi, Anna Liljedahl, Therese Anderson, L. Brian Perkins, Steven Bernsen, Tiffany Gatesman, Karl J. Kreutz