Estimation of the source parameters of the Himalaya earthquake of October 19, 1991, average effective shear wave attenuation parameter and local site effects from accelerograms

Kumar, Dinesh; Sarkar, Irene; Sriram, V.; Khattri, K. N.

doi:10.1016/j.tecto.2005.06.006

Cited by 42 publications

(8 citation statements)

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“…Model predictions of friction coefficients for a wide range of strain rate using a grain size of 30 mm, an effective normal stress of 100 MPa and temperatures of 100, 200, 300, and 400°C. agree relatively well with static stress drop estimates from earthquakes covering a large magnitude range [Abercrombie and Rice, 2005;Duni and Kuka, 2005;Kanamori, 1994;Konstantinou et al, 2005;Kumar et al, 2005;McGarr and Fletcher, 2002;Scholz, 2002].…”

Section: Implications For Seismogenesissupporting

confidence: 70%

A microphysical model for strong velocity weakening in phyllosilicate‐bearing fault gouges

2007

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[1] Previous rotary shear experiments, performed on a halite-muscovite fault gouge analogue system have shown that the presence of phyllosilicates, under conditions favoring the operation of cataclasis and pressure solution in the matrix phase, can have major effects on the frictional behavior of gouges. While 100% halite and 100% muscovite samples exhibit rate-independent frictional/brittle behavior, the strength of mixtures containing 10-30% muscovite is both normal stress and sliding velocitydependent. At high sliding velocities (>1 mm s À1 ), such mixtures show unusually marked velocity weakening, along with the development of a structureless, cataclastic microstructure. In the present paper, a micromechanical model is developed in an attempt to explain this behavior. The model assumes a granular flow process involving competition between intergranular dilatation and compaction by pressure solution. The predictions of the model agree favorably with the experimental results. Extension of the model to quartz-mica systems implies that the presence of phyllosilicates plus the operation of pressure solution can strongly promote (unstable) velocity-weakening behavior at rapid slip rates on natural faults, under midcrustal conditions. Static stress drop predictions based on the model agree reasonably well with estimates from seismic observations. Our results may help explain the discrepancy between laboratory-derived rate-and-state friction parameter values, obtained for dry, low-strain and/or single-phase rock systems, and the values for natural fault rocks inferred from seismological data.Citation: Niemeijer, A. R., and C. J. Spiers (2007), A microphysical model for strong velocity weakening in phyllosilicate-bearing fault gouges,

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Section: Implications For Seismogenesissupporting

confidence: 70%

A microphysical model for strong velocity weakening in phyllosilicate‐bearing fault gouges

2007

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“…In the present analysis, the corner frequency has been taken from the acceleration spectra since earthquakes are of low to moderate magnitudes and can directly be picked from the spectral acceleration (Kumar et al 2005). However, this assumption is not valid for large earthquakes, because low-value corner frequency may be eliminated during the filtering of the data.…”

Section: The Spreading Factor H N Is Computed Asmentioning

confidence: 99%

Rapid Estimation of Source Parameters Using Finite Fault Modeling--Case Studies from the Sikkim and Garhwal Himalayas

Raj¹,

Nath²,

Bansal³

et al. 2009

Seismological Research Letters

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“…GUPTA et al (1995) andMANDAL et al (2001) have earlier obtained the coda-Q estimates of the region using single backscattering model (AKI and CHOUET, 1975). The estimates of Q b based on strong motion data of the 1991 Uttarkashi and 1999 Chamoli earthquakes in the region are available (SINGH et al, 2004;DINESH et al, 2005;SRIRAM et al, 2005). However, the waveforms of strong motion data are affected more by source characteristics as compared to the weak motion data considered here.…”

Section: Introductionmentioning

confidence: 99%

Attenuation of P- and S-waves in the Chamoli Region, Himalaya, India

Sharma

Teotia

Kumar

et al. 2009

Pure Appl. Geophys.

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The attenuation properties of the crust in the Chamoli region of Himalaya have been examined by estimating the frequency-dependent relationships of quality factors for P waves (Q a ) and for S waves (Q b ) in the frequency range 1.5-24 Hz. The extended coda normalization method has been applied on the waveforms of 25 aftershocks of the 1999 Chamoli earthquake (M 6.4) recorded at five stations. The average value of Q a is found to be varied from 68 at 1.5 Hz to 588 at 24 Hz while it varies from 126 at 1.5 Hz to 868 at 24 Hz for Q b . The estimated frequency-dependent relations for quality factors are Q a = (44 ± 1)f (0.82±.04) and Q b = (87 ± 3)f (0.71±.03) . The rate of increase of Q(f) for P and S waves in the Chamoli region is comparable with the other regions of the world. The ratio Q b /Q a is greater than one in the region which along with the frequency dependence of quality factors indicates that scattering is an important factor contributing to the attenuation of body waves in the region. A comparison of attenuation relation for S wave estimated here (Q b = 87f 0.71 ) with that of coda waves (Q c = 30f 1.21 ) obtained by MANDAL et al. (2001) for the same region shows that Q c > Q b for higher frequencies (>8 Hz) in the region. This indicates a possible high frequency coda enrichment which suggests that the scattering attenuation significantly influences the attenuation of S waves at frequencies >8 Hz. This observation may be further investigated using multiple scattering models. The attenuation relations for quality factors obtained here may be used for the estimation of source parameters and near-source simulation of earthquake ground motion of the earthquakes, which in turn are required for the assessment of seismic hazard in the region.

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Estimation of the source parameters of the Himalaya earthquake of October 19, 1991, average effective shear wave attenuation parameter and local site effects from accelerograms

Cited by 42 publications

References 40 publications

A microphysical model for strong velocity weakening in phyllosilicate‐bearing fault gouges

A microphysical model for strong velocity weakening in phyllosilicate‐bearing fault gouges

Rapid Estimation of Source Parameters Using Finite Fault Modeling--Case Studies from the Sikkim and Garhwal Himalayas

Attenuation of P- and S-waves in the Chamoli Region, Himalaya, India

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