Frequency-dependent body wave attenuation characteristics in the Kumaun Himalaya

Singh, Charan; Singh, Arun; Bharathi, Vellaichamy; Bansal, A. R.; Chadha, R. K.

doi:10.1016/j.tecto.2011.12.013

Cited by 39 publications

(16 citation statements)

References 34 publications

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“…5) to the estimates obtained in other tectonic areas. The pattern is almost similar to that of Kummaun, India (Singh et al 2012). However, the higher estimates of −1 is mainly attributed to higher degree of heterogeneities in the crust beneath the study area.…”

Section: Resultssupporting

confidence: 76%

Quantifying Regional Body Wave Attenuation in a Seismic Prone Zone of Northeast India

Bora

Biswas

2017

Pure Appl. Geophys.

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Section: Resultssupporting

confidence: 76%

Quantifying Regional Body Wave Attenuation in a Seismic Prone Zone of Northeast India

Bora

Biswas

2017

Pure Appl. Geophys.

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“…Adams and Abercrombie (1998) estimated the attenuation around the Cajon Pass, southern California, and found that Q from surface data exhibits strong frequency dependence below 10 Hz, but only weak frequency dependence at higher frequency. This observation was also validated by Singh et al (2012) in the Kumaun Himalaya. Abercrombie (1997) suggested that if the frequency independent Q is the case, then the spectral ratios between two different recording depths will have a linear slope on a log-linear plot.…”

Section: Spectral Ratio Methodssupporting

confidence: 66%

Near-Surface Attenuation and Velocity Structures in Taiwan from Wellhead and Borehole Recordings Comparisons

Wang¹,

Fong²,

Wu³

et al. 2016

Terr. Atmos. Ocean. Sci.

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By analyzing the data from 28 seismic borehole stations deployed by the Central Weather Bureau Seismic Network throughout Taiwan from 2007 to 2014, we estimated the near-surface velocity (Vp and Vs) and attenuation (Qp and Qs) structures from surface to depths of approximately 300 m. To ensure that the deeper recordings were on the ray path between the seismic source and upper receiver, only events with an incidence angle of less than 35° were selected. Local magnitudes of analyzed events were between 1.1 and 6.6. The subsurface Qp and Qs were well modeled in the 5 -40 Hz frequency band using the spectral ratio of direct P-and S-waves, respectively, at each station, under frequency-independent Q and ω 2 source model assumptions. The estimated Vp in the Coastal Plain, the Western Foothills, the Longitudinal Valley, and the Yilan Plain were approximately 1000 -2000 m s -1 , which was lower than the Vp of 2500 -4000 m s -1 in the Central Mountain Range. In addition, the Vs in the plain areas were lower than that in the Central Mountain Range. The low Vp and Vs and high Vp/Vs ratio in the Coastal Plain and the Western Foothills can be attributed to the unconsolidated soil and high pore-fluid content of subsurface sediments in the plain areas. In contrast to the velocity distribution, low Qp and Qs were observed in the Central Mountain Range. The low Qp and Qs with low Vp/Vs and low Qs/Qp ratios in the Central Mountain Range was consistent with the high thermal temperature observed in the field investigation. The obtained velocity and attenuation structures near surface could also provide important constraints in validation of the crustal structure of Taiwan.

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“…Laboratory studies of melt‐free olivine‐dominated rocks show that Q increases as f 0.2–0.3 [e.g., Faul and Jackson , ], but comparable studies have not been done on crustal rocks. Many studies of seismic wave propagation in continental crust show stronger frequency dependence in tectonically active areas ( Q ~ f 0.4–0.7 ) [ Mitchell , ], and significant bulk modulus attenuation (indicated by Q P / Q S < 1) [e.g., Singh et al ., ; Hazarika et al ., ] unlike the laboratory studies, making it difficult to directly apply laboratory studies of high‐temperature mantle rocks to our crustal study, even with corrections for homologous temperature. Moreover, some of these crustal observations of frequency dependence have been called into question as a potential effect of incorrect geometric spreading corrections [ Morozov , ], so for simplicity we neglect this potential frequency dependence, and report only frequency‐independent t * and Q .…”

Section: Attenuation Measurementsmentioning

confidence: 99%

Physical state of Himalayan crust and uppermost mantle: Constraints from seismic attenuation and velocity tomography

et al. 2014

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We jointly interpret P and S wave seismic attenuation (1/Q) along with previously published seismic velocity results for the crust and uppermost mantle of eastern Nepal and the southern Tibetan Plateau. Seismic attenuation measurements can provide information complementary to seismic velocity estimates and can help distinguish between compositional and thermal mechanisms for observed anomalies. In addition to a dramatic change in seismic velocity observed between the crust of Nepal and southern Tibet, we find a large increase in seismic attenuation from high Q (low attenuation) in eastern Nepal to low Q (high attenuation) in the crust beneath southern Tibet for both P waves and S waves. We interpret the broad zone of low Q values in the southern Tibetan crust as thermal in origin, requiring an elevated geotherm (warm) relative to Nepal, with low V P /V S corresponding to a dominantly felsic middle and upper crust beneath southern Tibet. We find a sharply bounded region with enhanced low Q and high V P /V S at 45-50 km depth beneath southern Tibet, which we suggest may be due to trapped fluid beneath an impermeable cap associated with the crustal alpha-beta quartz transition. Using calibrations from mineral physics, the alpha-beta quartz transition suggests a temperature of 930-960°C at 45 km depth (50 km beneath the surface) beneath the southern Tibetan Plateau. High values of Q P and Q S throughout the uppermost mantle in the region are consistent with cool temperatures in the underthrusting Indian Plate, contributing to brittle conditions and earthquakes in the uppermost mantle.

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Frequency-dependent body wave attenuation characteristics in the Kumaun Himalaya

Cited by 39 publications

References 34 publications

Quantifying Regional Body Wave Attenuation in a Seismic Prone Zone of Northeast India

Quantifying Regional Body Wave Attenuation in a Seismic Prone Zone of Northeast India

Near-Surface Attenuation and Velocity Structures in Taiwan from Wellhead and Borehole Recordings Comparisons

Physical state of Himalayan crust and uppermost mantle: Constraints from seismic attenuation and velocity tomography

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