Pre-Failure Strain Localization in Siliclastic Rocks: A Comparative Study of Laboratory and Numerical Approaches


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Date

2024-08

Publication Type

Journal Article

ETH Bibliography

yes

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Abstract

We combined novel laboratory techniques and numerical modeling to investigate (a) seismic preparatory processes associated with deformation localization during a triaxial failure test on a dry sample of Berea sandstone. Laboratory observations were quantified by measuring strain localization on the sample surface with a distributed strain sensing (DSS) array, utilizing optical fibers, in conjunction with both passive and active acoustic emission (AE) techniques. A physics-based computational model was subsequently employed to understand the underlying physics of these observations and to establish a spatio-temporal correlation between the laboratory and modeling results. These simulations revealed three distinct stages of preparatory processes: (i) highly dissipative fronts propagated towards the middle of the sample correlating with the observed acoustic emission locations; (ii) dissipative regions were individuated in the middle of the sample and could be linked to a discernible decrease of the P-wave velocities; (iii) a system of conjugate bands formed, coalesced into a single band that grew from the center towards the sample surface and was interpreted to be representative for the preparation of a weak plane. Dilatative lobes at the process zones of the weak plane extended outwards and grew to the surface, causing strain localization and an acceleration of the simulated deformation prior to failure. This was also observed during the experiment with the strain rate measurements and spatio-temporally correlated with an increase of the seismicity rate in a similar rock volume. The combined approach of such laboratory and numerical techniques provides an enriched view of (a)seismic preparatory processes preceding the mainshock.

Publication status

published

Editor

Book title

Volume

57 (8)

Pages / Article No.

5371 - 5395

Publisher

Springer

Event

Edition / version

Methods

Software

Geographic location

Date collected

Date created

Subject

Strain localization; Preparatory processes; Acoustic emissions; Distributed strain sensing with optical fibers; Continuum-based numerical modeling

Organisational unit

03698 - Tackley, Paul / Tackley, Paul check_circle
09636 - Behr, Whitney / Behr, Whitney check_circle

Notes

Funding

192017 - Advancing laboratory seismology for improving the forecasting of natural and induced earthquakes (SNF)
856559 - Fault Activation adn Earthquake Rupture (EC)
170766 - Physical constraints on natural and induced earthquakes using innovative lab-scale experiments: The LabQuake Machine (SNF)

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