Regional seismic discrimination in central Asia with emphasis on western China

Hartse, Hans E.; Taylor, S.R.; Phillips, W. S.; Randall, George E.

doi:10.2172/378792

Cited by 52 publications

(81 citation statements)

References 4 publications

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“…The velocities that we use to define the widths of the P n windows are7.6 and 8:2 km=sec, and those for S n windows are 4.0 and 4:7 km=sec (Hartse, et al, 1997). The windows are centered at the peaks of the phases.…”

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Geometric Spreading of Pn and Sn in a Spherical Earth Model

Yang¹,

Lay²,

Xie³

et al. 2007

Bulletin of the Seismological Society of America

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Geometric spreading of P n and S n waves in a spherical Earth model is different than that of classical headwaves and is frequency dependent. The behavior cannot be fully represented by a frequency-independent power-law model, as is commonly assumed. The lack of an accurate representation of P n and S n geometric spreading in a spherical Earth model impedes our ability to characterize Earth properties including anelasticity. We conduct numerical simulations to quantify P n and S n geometric spreading in a spherical Earth model with constant mantle-lid velocities. Based on our simulation results, we present new empirical P n and S n geometricspreading models in the form Gr; f 10 n 3 f =r 0 r 0 =r n 1 f logr 0 =rn 2 f and n i f n i1 logf=f 0 2 n i2 logf=f 0 n i3 , where i 1, 2, or 3; r is epicentral distance; f is frequency; r 0 1 km; and f 0 1 Hz. We derive values of coefficients n ij by fitting the model to computed P n and S n amplitudes for a spherical Earth model having a 40-km-thick crust, generic values of P and S velocities, and a constant-velocity uppermost mantle. We apply the new spreading model to observed data in Eurasia to estimate average P n attenuation, obtaining more reasonable results compared to using a standard power-law model. Our new P n and S n geometric-spreading models provide generally applicable reference behavior for spherical Earth models with constant uppermost-mantle velocities.

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Section: Methodsmentioning

confidence: 99%

“…We make spectral-amplitude measurements at 100 frequencies log-evenly distributed between 0.75 and 13 Hz. Amplitude at each frequency f i is calculated by taking the average of the amplitudes between frequencies f i = 2 p and 2 p f i (Bowman and Kennett, 1991;Hartse et al, 1997).…”

Section: Methodsmentioning

confidence: 99%

Geometric Spreading of Pn and Sn in a Spherical Earth Model

Yang¹,

Lay²,

Xie³

et al. 2007

Bulletin of the Seismological Society of America

View full text Add to dashboard Cite

show abstract

“…Higher-frequencies are generally thought to discriminate better (e.g. Walter et al, 1995;Hartse et al, 1997), but both lower signal and higher noise conspire to produce poor signal-to-noise ratios at these frequencies for a number of events.…”

Section: Methodsmentioning

confidence: 99%

“…Walter et al, 1995;Taylor, 1996;Hartse et al, 1997;Kim et al, 1997;Rodgers and Walter, 2002;Taylor et al, 2002;Bottone et al, 2002;Walter et al, 2007). The application of this discriminant to broad regions, however, has been hampered by large variations in the amplitudes of phases due to propagation effects in the crust and upper mantle.…”

Section: Introductionmentioning

confidence: 99%

Testing Event Discrimination over Broad Regions using the Historical Borovoye Observatory Explosion Dataset

Pasyanos

Ford

Walter

2012

Pure Appl. Geophys.

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We test the performance of high-frequency regional P/S discriminants to differentiate between earthquakes and explosions at test sites and over broad regions using a historical dataset of explosions recorded at the Borovoye observatory in Kazakhstan. We compare these explosions to modern recordings of earthquakes at the same location. We then evaluate the separation of the two types of events using the raw measurements and those where the amplitudes are corrected for 1-D and 2-D attenuation structure. We find that high-frequency P/S amplitudes can reliably identify earthquakes and explosions and that the discriminant is applicable over broad regions as long as propagation effects are properly accounted for. Lateral attenuation corrections provide the largest improvement in the 2-4 Hz band, the use of which may allow us to examine smaller, distant events that have lower signal-to-noise at higher frequencies. We also find variations in P/S ratios among the three main nuclear testing locations within the Semipalatinsk Test Site which, due to their nearly identical paths to BRVK, must be a function of differing geology and emplacement conditions.

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“…These station-centric discriminants are known to be robust to instrument response calibration, and this calculation also removes the effect of magnitude. In the literature, station discriminants are then corrected for distance with a regression model built from earthquake calibration data (see Hartse et al, 1997;Bottone et al, 2002). Analogous to the development in the section titled The MDAC Discriminant: Model Inadequacy and Station Noise, define the random variable X ijk to be the regression corrected station discriminant for source type i 0; 1 (earthquake, explosion), event j, and station k (observed station discriminants are denoted x ijk ).…”

Section: Nts Data Analysis With a Regression Correction Multistation mentioning

confidence: 99%

Regional Multistation Discriminants: Magnitude, Distance, and Amplitude Corrections, and Sources of Error

Anderson¹,

Walter²,

Fagan³

et al. 2009

Bulletin of the Seismological Society of America

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Magnitude, distance, and amplitude corrections (MDAC) made to observed regional amplitudes are necessary so that what remains in the corrected amplitude is mostly information about the seismic source type. Corrected amplitudes can be used in ratios to discriminate between earthquakes and explosions. However, source effects remain that cannot easily be determined and applied as amplitude corrections, such as those due to depth, focal mechanism, local material property, and apparent stress variability. We develop a mathematical model to capture these nearsource effects as random (unknown), giving an error partition of three sources: model inadequacy, station noise, and amplitude correlation. This mathematical model is the basis for a general multistation regional discriminant formulation. The standard error of the discriminant includes the variances of model inadequacy and station noise, along with amplitude correlation in its formulation. The developed methods are demonstrated for a collection of Nevada test site (NTS) events observed at regional stations (see Fig. 1). Importantly, the proposed formulation includes all corrected amplitude information through the construction of multistation discriminants. In contrast, previous studies have only computed discriminants from single stations having both P and S amplitudes. The proposed multistation approach has similarities to the wellestablished m b versus M s discriminant and represents a new paradigm for the regional discrimination problem.

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Regional seismic discrimination in central Asia with emphasis on western China

Cited by 52 publications

References 4 publications

Geometric Spreading of Pn and Sn in a Spherical Earth Model

Geometric Spreading of Pn and Sn in a Spherical Earth Model

Testing Event Discrimination over Broad Regions using the Historical Borovoye Observatory Explosion Dataset

Regional Multistation Discriminants: Magnitude, Distance, and Amplitude Corrections, and Sources of Error

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