Characteristic features of local breakdown near a crack-tip in the transition zone from nucleation to unstable rupture during stick-slip shear failure

Ohnaka, Mitiyasu; Kuwahara, Yasuto

doi:10.1016/0040-1951(90)90138-x

Cited by 177 publications

(170 citation statements)

References 17 publications

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“…This kind of observation suggests that the existence of a nucleation region of an earthquake whose size might scale as the eventual size, as expected by rock experiments (e.g. Ohnaka and Kuwahara, 1990) and theoretical studies (e.g. Shibazaki and Matsu'ura, 1998).…”

Section: Introductionsupporting

confidence: 59%

Scaling relationships between sizes of nucleation regions and eventual sizes of microearthquakes

Hiramatsu

Furumoto

2007

Tectonophysics

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We investigate the initial rupture process of microearthquakes to reveal relationships between nucleation region sizes and eventual earthquake sizes. In order to obtain high quality waveform data, we installed a trigger recording system with a sampling frequency of 10 kHz at the base of a deep borehole at the Nojima Fault, Japan.We analyze waveform data of 31 events around the borehole, with seismic moment ranging from 4.2x10 9 Nm to 7.1x10 11 Nm. We use both a circular crack model with an accelerating rupture velocity (SK model) (Sato and Kanamori, 1999), which generates a slow initial phase of velocity pulse, and a circular crack model with a constant rupture velocity (SH model) (Sato and Hirasawa, 1973), which generates a ramp-like velocity pulse. Source parameters of these two models are estimated by waveform inversion of the first half cycle of the observed velocity pulse applying both a grid search and a non-linear least squares method. 14 of 31 events are never reproduced by the SH model with a constant Q operator. But SK model with a constant Q operator provides a size of the pre-existing crack, corresponding to the size of the nucleation regions, and a size of -3 -the eventual crack. We recognize that (i) the eventual seismic moment is approximately scaled as the cube of the size of pre-existing cracks, (ii) the eventual seismic moment is scaled as the cube of the size of eventual cracks, and (iii) the size of eventual cracks is roughly proportional to the size of pre-existing cracks. We, thus, conclude that the size of eventual earthquakes is controlled by the size of the nucleation regions.

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Section: Introductionsupporting

confidence: 59%

Scaling relationships between sizes of nucleation regions and eventual sizes of microearthquakes

Hiramatsu

Furumoto

2007

Tectonophysics

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“…Sampling rates are typically kilohertz to megahertz. For example, Dieterich (1978a) and Ohnaka and Kuwahara (1990) used semiconductor strain gauges to monitor analogue earthquakes in granite in a block model set-up. Pressure gauges have been used by Niewland et al (2000) to measure stress in situ in analogue models potentially useful for analogue earthquake models in future.…”

Section: Local Monitoring Techniquesmentioning

confidence: 99%

Analogue earthquakes and seismic cycles: experimental modelling across timescales

2017

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Abstract. Earth deformation is a multi-scale process ranging from seconds (seismic deformation) to millions of years (tectonic deformation). Bridging short-and long-term deformation and developing seismotectonic models has been a challenge in experimental tectonics for more than a century. Since the formulation of Reid's elastic rebound theory 100 years ago, laboratory mechanical models combining frictional and elastic elements have been used to study the dynamics of earthquakes. In the last decade, with the advent of high-resolution monitoring techniques and new rock analogue materials, laboratory earthquake experiments have evolved from simple spring-slider models to scaled analogue models. This evolution was accomplished by advances in seismology and geodesy along with relatively frequent occurrences of large earthquakes in the past decade. This coincidence has significantly increased the quality and quantity of relevant observations in nature and triggered a new understanding of earthquake dynamics. We review here the developments in analogue earthquake modelling with a focus on those seismotectonic scale models that are directly comparable to observational data on short to long timescales. We lay out the basics of analogue modelling, namely scaling, materials and monitoring, as applied in seismotectonic modelling. An overview of applications highlights the contributions of analogue earthquake models in bridging timescales of observations including earthquake statistics, rupture dynamics, ground motion, and seismic-cycle deformation up to seismotectonic evolution.

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“…Surfaces that have been artificially ground flat have diminished long-wavelength roughness above the corner wavelength λ c which is related to the grit size used for grinding [Brown and Scholz, 1985;Ohnaka and Kuwahara, 1990;Marone and Cox, 1994]. AEs with dimensions smaller than λ c will most likely be arrested, but AEs that become larger than λ c are unlikely to encounter a strength barrier that will arrest their propagation.…”

Section: 1002/2014jb011220mentioning

confidence: 99%

Preslip and cascade processes initiating laboratory stick slip

2014

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Recent modeling studies have explored whether earthquakes begin with a large aseismic nucleation process or initiate dynamically from the rapid growth of a smaller instability in a "cascade-up" process. To explore such a case in the laboratory, we study the initiation of dynamic rupture (stick slip) of a smooth saw-cut fault in a 76 mm diameter cylindrical granite laboratory sample at 40-120 MPa confining pressure. We use a high dynamic range recording system to directly compare the seismic waves radiated during the stick-slip event to those radiated from tiny (M À6) discrete seismic events, commonly known as acoustic emissions (AEs), that occur in the seconds prior to each large stick slip. The seismic moments, focal mechanisms, locations, and timing of the AEs all contribute to our understanding of their mechanics and provide us with information about the stick-slip nucleation process. In a sequence of 10 stick slips, the first few microseconds of the signals recorded from stick-slip instabilities are nearly indistinguishable from those of premonitory AEs. In this sense, it appears that each stick slip begins as an AE event that rapidly (~20 μs) grows about 2 orders of magnitude in linear dimension and ruptures the entire 150 mm length of the simulated fault. We also measure accelerating fault slip in the final seconds before stick slip. We estimate that this slip is at least 98% aseismic and that it both weakens the fault and produces AEs that will eventually cascade-up to initiate the larger dynamic rupture.

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Characteristic features of local breakdown near a crack-tip in the transition zone from nucleation to unstable rupture during stick-slip shear failure

Cited by 177 publications

References 17 publications

Scaling relationships between sizes of nucleation regions and eventual sizes of microearthquakes

Scaling relationships between sizes of nucleation regions and eventual sizes of microearthquakes

Analogue earthquakes and seismic cycles: experimental modelling across timescales

Preslip and cascade processes initiating laboratory stick slip

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