气候变化领域集成服务门户(CCPortal): Source Mechanisms of Laboratory Earthquakes During Fault Nucleation and Formation

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DOI	10.1029/2020JB021059
	Source Mechanisms of Laboratory Earthquakes During Fault Nucleation and Formation
	King T.; Vinciguerra S.; Burgess J.; Benson P.; De Siena L.
发表日期	2021
ISSN	21699313
卷号	126 期号:5
英文摘要	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. © 2021. The Authors.
英文关键词	acoustic emission; focal mechanism; fracture; precusory; rock deformation
语种	英语
来源期刊	Journal of Geophysical Research: Solid Earth
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/187146
作者单位	Department of Earth Sciences, University of Turin, Turin, Italy; Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Catania - Osservatorio Etneo, Catania, Italy; Rock Mechanics Laboratory, School of Earth and Environmental Sciences, University of Portsmouth, Portsmouth, United Kingdom; Institute of Geosciences, Johannes Gutenberg University, Mainz, Germany; Department of Geology and Petroleum Geology, School of Geosciences, King's College, University of Aberdeen, Aberdeen, United Kingdom
推荐引用方式 GB/T 7714	King T.,Vinciguerra S.,Burgess J.,et al. Source Mechanisms of Laboratory Earthquakes During Fault Nucleation and Formation[J],2021,126(5).
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).
MLA	King T.,et al."Source Mechanisms of Laboratory Earthquakes During Fault Nucleation and Formation".Journal of Geophysical Research: Solid Earth 126.5(2021).