Traces Of Laboratory Earthquake Nucleation In The Spectrum Of Ambient Noise

Abstract

The short-term forecast of earthquakes associated with fault rupture is a challenge in seismology and rock mechanics. The evolution of mechanical characteristics of a local fault segment may be encoded in the ambient noise, thus, converting the ambient noise to an efficient source of information about the fault stress-strain conditions. In laboratory experiments we investigate micro-vibrations of a block-fault system induced by weak external disturbances with the purpose of getting reliable evidence of how the system transits to the metastable state. We show that precursory changes of spectral characteristics of micro-vibrations are observed for the complete spectrum of failure modes. In the course of experiments we systematically change the properties of interface to perform the transition from stick-slip to steady sliding and observe the characteristics of micro-vibrations of the laboratory block-fault system. Detected were systematical alterations of the system natural frequency and those alterations were determined by the evolution of fault stiffness. The detected regularities suggest that the final stage of seismic event preparation can be revealed in analyzing the spectral characteristics of ambient noise. The detection of natural oscillations of a block-fault system can be a new useful tool to monitor active faults in real time.

Constitutive Behavior of Rocks During the Seismic Cycle

“…But most importantly, the state variables that encapsulate the evolutionary effects originate from measurable physical quantities, may it be the real area of contact (Aharonov & Scholz, 2018, 2019; Bar‐Sinai et al., 2014; Barbot, 2019b, 2022; Boitnott et al., 1992; Bowden & Tabor, 1964; Sleep, 2006) or the porosity (J. Chen, 2023; J. Chen & Spiers, 2016; J. Chen et al., 2017; Sleep, 2005). The evolving texture of the fault gouge influences other observables, including fluid permeability (Im et al., 2019; Proctor et al., 2020), electrical conductivity (Yamashita et al., 2014), acoustic transmissivity (Fukuyama et al., 2019; Kocharyan et al., 2018; Nagata et al., 2008, 2012; Rouet‐Leduc et al., 2018), optical transparency and reflectivity (Bayart et al., 2018; Ben‐David et al., 2010; Dieterich & Kilgore, 1994; Rubinstein et al., 2004; Selvadurai & Glaser, 2015, 2017), fault compaction and dilatancy (Carpenter, Ikari, & Marone, 2016; Marone et al., 1990), and the density of off‐fault damage (Goebel et al., 2014). Hence, these physical quantities can serve as proxies for state variables in nature or in the laboratory, potentially explaining subtle changes in crustal properties shortly before and after earthquakes (Brenguier et al., 2008; Kato & Ben‐Zion, 2021; Y. Li et al., 1998).…”

“…Chen et al, 2017;Sleep, 2005). The evolving texture of the fault gouge influences other observables, including fluid permeability (Im et al, 2019;Proctor et al, 2020), electrical conductivity (Yamashita et al, 2014), acoustic transmissivity (Fukuyama et al, 2019;Kocharyan et al, 2018;Nagata et al, 2008Nagata et al, , 2012Rouet-Leduc et al, 2018), optical transparency and reflectivity (Bayart et al, 2018;Ben-David et al, 2010;Dieterich & Kilgore, 1994;Rubinstein et al, 2004;Selvadurai & Glaser, 2015, fault compaction and dilatancy (Carpenter, Ikari, & Marone, 2016;Marone et al, 1990), and the density of off-fault damage (Goebel et al, 2014). Hence, these physical quantities can serve as proxies for state variables in nature or in the laboratory, potentially explaining subtle changes in crustal properties shortly before and after earthquakes (Brenguier et al, 2008;Kato & Ben-Zion, 2021;Y.…”

Orientation-dependent optic-fiber accelerometer based on excessively tilted fiber grating

“…Vibration (acceleration) monitoring and detection are extremely important for engineering structural health, geological prospecting, space flight and aviation, and so on [1][2][3]. Compared with traditional vibration accelerometers based on piezoelectric or microelectromechanical systems (MEMS), optic-fiber based sensing techniques possess the advantages including high sensitivity, compact size, immunization to electromagnetic, remote sensing and resistance to hash environment.…”

ISSLEDOVANIE PROCESSA PODGOTOVKI SEJSMIChESKIH SOBYTIJ S POMOShh''Ju ANALIZA NIZKOChASTOTNOGO SEJSMIChESKOGO ShUMA

“…В последнее десятилетие сформировалась гипотеза о том, что при переходе очаговой области будущего землетрясения в метастабильное состояние механические характеристики разломной зоны должны заметно изменяться, а в последние годы эта гипотеза была подтверждена и экспериментально [1,2]. Если этот эффект имеет место в натурных условиях, то может существовать возможность инструментального контроля изменений напряженнодеформированного состояния разломной зоны на заключительной стадии подготовки землетрясения.…”