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Source mechanisms of laboratory earthquakes during fault nucleation and formation

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Source mechanisms of laboratory earthquakes during fault nucleation and formation. / King, Thomas; Vinciguerra, Sergio; Burgess, Jodi; Benson, Philip; De Siena, Luca.

In: Journal of Geophysical Research: Solid Earth, Vol. 126, No. 5, e2020JB021059, 07.05.2021.

Research output: Contribution to journalArticlepeer-review

Harvard

King, T, Vinciguerra, S, Burgess, J, Benson, P & De Siena, L 2021, 'Source mechanisms of laboratory earthquakes during fault nucleation and formation', Journal of Geophysical Research: Solid Earth, vol. 126, no. 5, e2020JB021059. https://doi.org/10.1029/2020JB021059

APA

King, T., Vinciguerra, S., Burgess, J., Benson, P., & De Siena, L. (2021). Source mechanisms of laboratory earthquakes during fault nucleation and formation. Journal of Geophysical Research: Solid Earth, 126(5), [e2020JB021059]. https://doi.org/10.1029/2020JB021059

Vancouver

King T, Vinciguerra S, Burgess J, Benson P, De Siena L. Source mechanisms of laboratory earthquakes during fault nucleation and formation. Journal of Geophysical Research: Solid Earth. 2021 May 7;126(5). e2020JB021059. https://doi.org/10.1029/2020JB021059

Author

King, Thomas ; Vinciguerra, Sergio ; Burgess, Jodi ; Benson, Philip ; De Siena, Luca. / Source mechanisms of laboratory earthquakes during fault nucleation and formation. In: Journal of Geophysical Research: Solid Earth. 2021 ; Vol. 126, No. 5.

Bibtex

@article{6be00fa62abc4722a50801c12d55ae79,
title = "Source mechanisms of laboratory earthquakes during fault nucleation and formation",
abstract = "Identifying deformation and pre-failure mechanisms preceding faulting is key for fault mechanics and for interpreting precursors to fault rupture. This study presents the results of a new and robust derivation of first motion polarity focal mechanism solutions (FMS) applied to acoustic emission (AE). FMS are solved using a least squares minimization of the fit between projected polarity measurements and the deviatoric stress field induced by dilatational (T-type), shearing (S-type), and compressional (C-type) sources. 4 × 10 cm cylindrical samples of Alzo Granite (AG, porosity <1%) and Darley Dale Sandstone (DDS, porosity ≈14%) underwent conventional triaxial tests in order to investigate the relationships between increasing confining pressure (5, 10, 20, and 40 MPa), deformation and failure mode, and role of microstructural features. Results highlight that S-type events occur in very low numbers with poor spatial correlation to fault structure. Instead, deformation is driven by a complex interplay between compactant (C-type) and dilatant (T-type) regions of deformation. C-type events are the earliest precursor related to crack nucleation and T-type events mark new cracks opening, with the onset of fracture growth characterized by periodic cycles of coalescence. For AG a single sequence is able to lead to dynamic failure, while for DDS several cycles are needed for coalescence to take place due to the competition between dilatant and compactant deforming regions induced by multiple fracture nucleation sites. The occurrence of C- and S-type events is also consistent with a quasi-static premonitory phase, or foreshock, before a critical nucleation length allows the development of a planar localization.",
keywords = "acoustic emission, focal mechanism, fracture, precusory, rock deformation",
author = "Thomas King and Sergio Vinciguerra and Jodi Burgess and Philip Benson and {De Siena}, Luca",
note = "Publisher Copyright: {\textcopyright} 2021. The Authors.",
year = "2021",
month = may,
day = "7",
doi = "10.1029/2020JB021059",
language = "English",
volume = "126",
journal = "Journal of Geophysical Research: Solid Earth",
issn = "2169-9313",
publisher = "American Geophysical Union",
number = "5",

}

RIS

TY - JOUR

T1 - Source mechanisms of laboratory earthquakes during fault nucleation and formation

AU - King, Thomas

AU - Vinciguerra, Sergio

AU - Burgess, Jodi

AU - Benson, Philip

AU - De Siena, Luca

N1 - Publisher Copyright: © 2021. The Authors.

PY - 2021/5/7

Y1 - 2021/5/7

N2 - Identifying deformation and pre-failure mechanisms preceding faulting is key for fault mechanics and for interpreting precursors to fault rupture. This study presents the results of a new and robust derivation of first motion polarity focal mechanism solutions (FMS) applied to acoustic emission (AE). FMS are solved using a least squares minimization of the fit between projected polarity measurements and the deviatoric stress field induced by dilatational (T-type), shearing (S-type), and compressional (C-type) sources. 4 × 10 cm cylindrical samples of Alzo Granite (AG, porosity <1%) and Darley Dale Sandstone (DDS, porosity ≈14%) underwent conventional triaxial tests in order to investigate the relationships between increasing confining pressure (5, 10, 20, and 40 MPa), deformation and failure mode, and role of microstructural features. Results highlight that S-type events occur in very low numbers with poor spatial correlation to fault structure. Instead, deformation is driven by a complex interplay between compactant (C-type) and dilatant (T-type) regions of deformation. C-type events are the earliest precursor related to crack nucleation and T-type events mark new cracks opening, with the onset of fracture growth characterized by periodic cycles of coalescence. For AG a single sequence is able to lead to dynamic failure, while for DDS several cycles are needed for coalescence to take place due to the competition between dilatant and compactant deforming regions induced by multiple fracture nucleation sites. The occurrence of C- and S-type events is also consistent with a quasi-static premonitory phase, or foreshock, before a critical nucleation length allows the development of a planar localization.

AB - Identifying deformation and pre-failure mechanisms preceding faulting is key for fault mechanics and for interpreting precursors to fault rupture. This study presents the results of a new and robust derivation of first motion polarity focal mechanism solutions (FMS) applied to acoustic emission (AE). FMS are solved using a least squares minimization of the fit between projected polarity measurements and the deviatoric stress field induced by dilatational (T-type), shearing (S-type), and compressional (C-type) sources. 4 × 10 cm cylindrical samples of Alzo Granite (AG, porosity <1%) and Darley Dale Sandstone (DDS, porosity ≈14%) underwent conventional triaxial tests in order to investigate the relationships between increasing confining pressure (5, 10, 20, and 40 MPa), deformation and failure mode, and role of microstructural features. Results highlight that S-type events occur in very low numbers with poor spatial correlation to fault structure. Instead, deformation is driven by a complex interplay between compactant (C-type) and dilatant (T-type) regions of deformation. C-type events are the earliest precursor related to crack nucleation and T-type events mark new cracks opening, with the onset of fracture growth characterized by periodic cycles of coalescence. For AG a single sequence is able to lead to dynamic failure, while for DDS several cycles are needed for coalescence to take place due to the competition between dilatant and compactant deforming regions induced by multiple fracture nucleation sites. The occurrence of C- and S-type events is also consistent with a quasi-static premonitory phase, or foreshock, before a critical nucleation length allows the development of a planar localization.

KW - acoustic emission

KW - focal mechanism

KW - fracture

KW - precusory

KW - rock deformation

UR - http://www.scopus.com/inward/record.url?scp=85106893667&partnerID=8YFLogxK

U2 - 10.1029/2020JB021059

DO - 10.1029/2020JB021059

M3 - Article

AN - SCOPUS:85106893667

VL - 126

JO - Journal of Geophysical Research: Solid Earth

JF - Journal of Geophysical Research: Solid Earth

SN - 2169-9313

IS - 5

M1 - e2020JB021059

ER -

ID: 28098937