Source parameters, path attenuation and site effects from strong-motion recordings of the Wenchuan aftershocks (2008–2013) using a non-parametric generalized inversion technique

Wang, Hongwei; Ren, Yefei; Wen, Rong

doi:10.1093/gji/ggx447

Cited by 40 publications

(15 citation statements)

References 45 publications

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“…However, the dB e values for PGA and PSA at periods of \ 0.4 s in the Minxian earthquake are smaller than in WcA2. According to the same method used for calculating the Dr values for the Ludian, Jinggu, and Kangding earthquakes, the value of Dr estimated for the Minxian earthquake was 0.35 MPa, slightly lower than the value of Dr = 0.40 MPa for WcA2 provided by Wang et al (2018). Differences in the Dr values between the two earthquakes may potentially explain the different dB e values for short-period ground motions.…”

Section: Figurementioning

confidence: 90%

Observations on Regional Variability in Ground-Motion Amplitude from Six Mw ~ 6.0 Earthquakes of the North–South Seismic Zone in China

Ren

Wen

et al. 2019

Pure Appl. Geophys.

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Observed ground-motion intensity for six earthquakes of M w = 6.0-6.2 that occurred in China's North-South Seismic Zone (NSSZ) was compared with predicted medians from the BSSA14 model. The resulting between-event (dB e ) and withinevent (dW es ) residuals for peak ground acceleration and pseudospectral acceleration up to 5.0 s were used to investigate the impact of source effects and path propagation on the regional variability in observed ground-motion amplitude within the NSSZ. Although the magnitude and fault type were similar among the six earthquakes, the results showed that their source effects were significantly different, which contributed in part to the regional variability in observed ground-motion amplitude. Estimated values for stress drop were found to mirror the trend in variation of the dB e values for short-period ground motions in the six earthquakes. This suggests that stress drop is an important factor for accurate representation of source effects and should be considered in the functional form of ground-motion prediction equations. Anelastic attenuation of ground motion was found to be considerably different in local areas of the NSSZ, which may constitute the primary reason for the regional variability in the observed ground-motion amplitude. The variation in dW es values confirmed that regional adjustment of anelastic attenuation in the BSSA14 model is applicable to some local areas (i.e., around the Longmenshan fault) but not to the NSSZ in its entirety.

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Section: Figurementioning

confidence: 90%

Observations on Regional Variability in Ground-Motion Amplitude from Six Mw ~ 6.0 Earthquakes of the North–South Seismic Zone in China

Ren

Wen

et al. 2019

Pure Appl. Geophys.

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“…In order to resolve a remaining degree of freedom coming from the trade-offs between source and site terms, the constraining condition for either the source or the site should be fixed beforehand. The most commonly used method was to set the site response of an ideal outcrop bedrock site to be equal to unity irrespective of frequency (Wang et al, 2018), or to set the average site response of a set of rock sites to be equal to unity (Oth et al, 2009;Oth and Kaiser, 2014;Pacor et al, 2016) or the horizontal-to-vertical (H/V) spectral ratio of body waves (Bindi et al, 2004;Wang et al, 2018). The site conditions for the 25 strong-motion stations considered in this study were classified into three classes defined in the Code for Seismic Design of Buildings in China (GB 50011, 2010) according to the terrain-based metrics (Shi, 2009), 16 for class II (medium-stiff soil), eight for class III (medium soft soil), and one for class IV (soft soil); thus, no one can be approximately regarded as a rock site.…”

Section: Methodsmentioning

confidence: 99%

“…Studies associated with the earthquake source were of decisive importance for a deep understanding of the seismic source physics and reliable prediction of future ground motions and seismic hazards. The observed ground motion recordings have been commonly utilized in a number of established methods (e.g., empirical Green's function-based method and large-scale stacking and generalized inversion techniques) aimed at revealing the earthquake source characteristics, e.g., the earthquake source scaling (Allmann and Shearer, 2009;Viegas et al, 2010;Baruah et al, 2016;Trugmann and Shearer, 2017;Baltay et al, 2019) and the source rupture directivity (Abercrombie et al, 2017;Calderoni et al, 2017;Wang et al, 2018). The source characteristics have important implications for explaining the earthquake nucleation and growth (e.g., Moyer et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

Earthquake Source Characteristics and S-Wave Propagation Attenuation in the Junction of the Northwest Tarim Basin and Kepingtage Fold-and-Thrust Zone

Wang

Wen

2020

Front. Earth Sci.

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We separated the propagation path attenuation and source spectra from the S-wave Fourier amplitude spectra of the observed ground motions recorded during 46 small-to-moderate earthquakes in the junction of the northwest Tarim Basin and Kepingtage fold-and-thrust zone, mainly composed of two Jiashi seismic sequences in 2020 and 2018. Slow seismic wave decay was observed as the distance increased, while the quality factor regressed as 60.066 f0.988 for frequency f = 0.254–30 Hz reflects the strong anelastic attenuation in the study region. We estimated the stress drops for the 46 earthquakes under investigation from the preferred corner frequencies and seismic moments by fitting the inverted source spectra and the theoretical ω-square model. The relationship between seismic moment and corner frequency and the dependence of the stress drop on the moment magnitude reveal the breakdown of earthquake self-similar scaling for the events in this study. The temporal variation in stress drops indicates that the mainshock plays a short-term role in the source characteristics of the surrounding earthquakes. Aftershocks immediately following the mainshock show a low stress release and then gradually recover in a short time. The healing process for the fractured fault in the mainshock may be one reason for the stress drop recovery of the aftershock. The foreshock with the low stress release occurring in the high-heterogeneity fault zone may motivate the following occurrence of the largest magnitude mainshock with a high stress drop. We inferred that the foreshock-mainshock behavior, including several moderate events, may be predisposed to occur in our study region characterized by an inhomogeneous crust.

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“…Earthquake self‐similar scaling is a controversial issue characterized by a constant stress drop (Δ σ ) over a wide range of earthquake sizes. It was originally recognized by Aki (), and it has been observed in large numbers of earthquakes, for example, global moderate–large earthquakes (Allmann & Shearer, ), Japanese crustal or subcrustal earthquakes (Oth, ), and the 2008 Wenchuan seismic sequence (Wang et al, ). However, the breakdown of earthquake self‐similar scaling has been verified in certain specific seismic sequences, for example, the 2004 Les Saintes Guadeloupe seismic sequence (Drouet et al, ) and the 2009 L'Aquila seismic sequence (Pacor, Spallarossa, et al, ).…”

Section: Earthquake Self‐similar Scalingmentioning

confidence: 99%

Breakdown of Earthquake Self‐Similar Scaling and Source Rupture Directivity in the 2016–2017 Central Italy Seismic Sequence

et al. 2019

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To analyze the source characteristics of the 2016-2017 central Italy seismic sequence, source spectra of 78 earthquakes of M L = 3.5-6.1 were separated from the S wave Fourier spectra using the two-step nonparametric generalized inversion technique. Source parameters (e.g., stress drop) were estimated from the source spectra following the ω-square model. Stress drops were found mainly in the range 0. 113-12.190 MPa. The significant dependence of stress drop on magnitude indicates the breakdown of earthquake self-similar scaling in this sequence. The low stress drops for small events following the release of high stress by the mainshock might have led to stress accumulation on the unruptured fault, which could explain the subsequent occurrence of multiple major events. We investigated the source rupture directivity for 36 events through the azimuthal variation of apparent source spectra. Significant variation was observed at specific frequency bands (generally, over corner frequencies) in 10 events caused by rupture directivity, which was verified by the stable estimation of rupture plane. The rupture parameters confirmed unilateral ruptures predominantly on the NNW-SSE striking fault with fast rupture velocity (2.52-2.84 km/s) for the 10 events. Rupture parameters for an additional four events with stable estimated rupture plane were also analyzed. These were characterized by slow rupture velocity causing weak directivity effects. According to the rupture parameters for the 14 events, prevailing SSE or SEE (NNW or NNE) rupture directivity was a common feature for events to the north (south) of the mainshock in this earthquake sequence.

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Source parameters, path attenuation and site effects from strong-motion recordings of the Wenchuan aftershocks (2008–2013) using a non-parametric generalized inversion technique

Cited by 40 publications

References 45 publications

Observations on Regional Variability in Ground-Motion Amplitude from Six Mw ~ 6.0 Earthquakes of the North–South Seismic Zone in China

Observations on Regional Variability in Ground-Motion Amplitude from Six Mw ~ 6.0 Earthquakes of the North–South Seismic Zone in China

Earthquake Source Characteristics and S-Wave Propagation Attenuation in the Junction of the Northwest Tarim Basin and Kepingtage Fold-and-Thrust Zone

Breakdown of Earthquake Self‐Similar Scaling and Source Rupture Directivity in the 2016–2017 Central Italy Seismic Sequence

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