The Experts below are selected from a list of 252 Experts worldwide ranked by ideXlab platform
Jieyuan Ning - One of the best experts on this subject based on the ideXlab platform.
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Post-critical SsPmp and its Applications to Virtual Deep Seismic Sounding (VDSS)–3: Back-projection Imaging of the Crust-Mantle Boundary in a Heterogeneous Lithosphere
2020Co-Authors: Simon Louis Klemperer, Chunquan Yu, Jieyuan NingAbstract:Virtual Deep Seismic Sounding (VDSS) uses the arrival time of post-critical SsPmp relative to the direct S wave to infer Moho depth at the Pmp reflection point. Due to the large offset between the virtual source and the receiver, SsPmp is more sensitive to lateral variations of structures than near-vertical phases such as Ps that is used to construct conventional P receiver functions. However, the way post-critical SsPmp is affected by lateral variations in lithospheric structures is not well understood, and previous studies largely assumed a 1D structure when analyzing SsPmp waveforms. Here we present synthetic tests with various 2D models to show that lateral variations in lithospheric structures, from the lithosphere-asthenosphere Boundary to sedimentary basins, profoundly affect travel time, phase and amplitude of post-critical SsPmp, and that a 1D approximation is usually inappropriate when analyzing 2D data. Despite these strong effects we show, with synthetic examples and the ChinArray data from the Ordos Block in northern China, that a simple ray-theory-based back-projection method can retrieve the geometry of the Crust-Mantle Boundary given array observations in cases with moderate lateral variations in the Crust-Mantle Boundary and/or the lithosphere-asthenosphere Boundary. The success of our back-projection method indicates that ray-theory approximations are sufficient in modeling SsPmp travel times in the presence of moderate lateral heterogeneity. In contrast, we show that the ray theory is generally insufficient in modeling SsPmp phase shifts in a strongly heterogeneous lithosphere due to non-planar down-going P waves incident at the Crust-Mantle Boundary. Nonetheless, our results demonstrate the feasibility of direct imaging of the Crust-Mantle Boundary with post-critical SsPmp even in the presence of 2D variations of lithospheric structures.
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Post-critical SsPmp and its applications to Virtual Deep Seismic Sounding (VDSS)—1: sensitivity to lithospheric 1-D and 2-D structure
Geophysical Journal International, 2018Co-Authors: Simon Louis Klemperer, Chunquan Yu, Jieyuan NingAbstract:Virtual Deep Seismic Sounding (VDSS) has recently emerged as a novel method to image the Moho and potentially other lithospheric boundaries. The behaviour of SsPmp, the post-critical reflection phase at the Moho that is utilized in VDSS, is rich with complexities not yet widely considered. Here, motivated by observations from the Ordos Plateau in North China, we use synthetic seismograms computed with a broad range of 1-D models to evaluate how different parts of the lithosphere along the ray path of SsPmp affect its phase, amplitude and arrival time. Our findings include: (1) When the crust–mantle Boundary is a sharp discontinuity, the SsPmp phase shift relative to the direct S wave is controlled by lower-crustal V_p, upper-mantle V_p and ray parameter. This property indicates the possibility of using SsPmp to constrain V_p in the lower crust and uppermost mantle. (2) When the crust–mantle Boundary is a velocity-gradient zone, SsPmp arrival times vary as different functions of ray parameter from cases with a sharp crust–mantle Boundary, because different rays turn at different depths. This feature allows measurement of the vertical velocity gradient in the crust–mantle transition zone with SsPmp. (3) When the virtual source (location of S-to-P conversion at the free surface) is in a sedimentary basin, SsPmp amplitude can be significantly reduced due to low S-to-P reflected energy at the virtual source. This may cause the absence of SsPmp despite appropriate source–receiver geometry. In addition to 1-D models, we further conduct 2-D waveform modelling and find that the SsPmp arrival time relative to direct S is not only controlled by crustal thickness at the reflection point but also by lateral variation of V_s beneath the virtual source and receiver. Therefore, in areas with significant lateral heterogeneity in the lithosphere the accuracy of crustal-thickness measurements from SsPmp arrival times depends on our knowledge of the variability of lithospheric structure across a broad region.
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Post-critical SsPmp and Its Applications to Virtual Deep Seismic Sounding (VDSS): 1. Sensitivity to Lithospheric 1D and 2D structure
2018Co-Authors: Simon Louis Klemperer, Chunquan Yu, Jieyuan NingAbstract:Virtual Deep Seismic Sounding (VDSS) has recently emerged as a novel method to image the Moho and potentially other lithospheric boundaries. The behavior of SsPmp, the post-critical reflection phase at the Moho that is utilized in VDSS, is rich with complexities not yet widely utilized. Here, motivated by observations from the Ordos Plateau in North China, we use synthetic seismograms computed with a broad range of 1D models to evaluate how different parts of the lithosphere along the ray path of SsPmp affect its phase, amplitude, and arrival time. Our findings include: (1) When the Crust-Mantle Boundary is a sharp discontinuity, the SsPmp phase shift relative to the direct S wave is controlled by lower-crustal Vp, upper-mantle Vp and ray parameter. This property indicates the possibility of using SsPmp to constrain Vp in the lower crust and uppermost mantle. (2) When the Crust-Mantle Boundary is a velocity-gradient zone, SsPmp arrival times vary as different functions of ray parameter from cases with a sharp Crust-Mantle Boundary, because different rays turn at different depths. This feature allows measurement of the vertical velocity gradient in the Crust-Mantle transition zone with SsPmp. (3) When the virtual source (location of S-to-P conversion at the free surface) is in a sedimentary basin, SsPmp amplitude can be significantly reduced due to low S-to-P reflected energy at the virtual source. This may cause the absence of SsPmp despite appropriate source-receiver geometry. In addition to 1D models, we further conduct 2D waveform modeling and find that the SsPmp arrival time relative to direct S is not only controlled by crustal thickness at the reflection point, but also by lateral variation of Vs beneath the virtual source and receiver. Therefore, in areas with significant lateral heterogeneity in the lithosphere the accuracy of crustal-thickness measurements from SsPmp arrival times depends on our knowledge of the variability of lithospheric structure across a broad region.
Josep Gallart - One of the best experts on this subject based on the ideXlab platform.
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Complex images of Moho and variation of Vp/Vs across the Himalaya and South Tibet, from a joint receiver-function and wide-angle-reflection approach
Geophysical Research Letters, 2002Co-Authors: ALBERTO GALVE, J.-c. Lépine, Adriano Hirn, J Diaz, Mireille Laigle, Martine Sapin, Josep GallartAbstract:Teleseismic receiver functions (RF) allow us to image the spatial variation of the Crust-Mantle Boundary (Moho) along a tight array spanning from south of the Himalayas to the centre of the Tibetan Plateau. This approach is cross-tested with wide-angle reflection imaging (WARR). Highlighted by each of the two independent methods, a complex architecture of the Moho with dipping and overlapping segments indicating lithospheric imbrication, is confirmed. The joint use of the two methods reveals an increase of the average crustal P-to-S-wave-velocity ratio from south to the centre of the Lhasa block. This may be due to lowered S-wave velocity confined in specific layers, that may be interpreted as partial melt. This accounts for half of the relative increase in the delay of direct teleseismic S-wave arrivals with respect to P-wave arrivals from south to north, suggesting a similar anomaly in the shallower mantle.
Simon Louis Klemperer - One of the best experts on this subject based on the ideXlab platform.
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Post-critical SsPmp and its Applications to Virtual Deep Seismic Sounding (VDSS)–3: Back-projection Imaging of the Crust-Mantle Boundary in a Heterogeneous Lithosphere
2020Co-Authors: Simon Louis Klemperer, Chunquan Yu, Jieyuan NingAbstract:Virtual Deep Seismic Sounding (VDSS) uses the arrival time of post-critical SsPmp relative to the direct S wave to infer Moho depth at the Pmp reflection point. Due to the large offset between the virtual source and the receiver, SsPmp is more sensitive to lateral variations of structures than near-vertical phases such as Ps that is used to construct conventional P receiver functions. However, the way post-critical SsPmp is affected by lateral variations in lithospheric structures is not well understood, and previous studies largely assumed a 1D structure when analyzing SsPmp waveforms. Here we present synthetic tests with various 2D models to show that lateral variations in lithospheric structures, from the lithosphere-asthenosphere Boundary to sedimentary basins, profoundly affect travel time, phase and amplitude of post-critical SsPmp, and that a 1D approximation is usually inappropriate when analyzing 2D data. Despite these strong effects we show, with synthetic examples and the ChinArray data from the Ordos Block in northern China, that a simple ray-theory-based back-projection method can retrieve the geometry of the Crust-Mantle Boundary given array observations in cases with moderate lateral variations in the Crust-Mantle Boundary and/or the lithosphere-asthenosphere Boundary. The success of our back-projection method indicates that ray-theory approximations are sufficient in modeling SsPmp travel times in the presence of moderate lateral heterogeneity. In contrast, we show that the ray theory is generally insufficient in modeling SsPmp phase shifts in a strongly heterogeneous lithosphere due to non-planar down-going P waves incident at the Crust-Mantle Boundary. Nonetheless, our results demonstrate the feasibility of direct imaging of the Crust-Mantle Boundary with post-critical SsPmp even in the presence of 2D variations of lithospheric structures.
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Post-critical SsPmp and its applications to Virtual Deep Seismic Sounding (VDSS)—1: sensitivity to lithospheric 1-D and 2-D structure
Geophysical Journal International, 2018Co-Authors: Simon Louis Klemperer, Chunquan Yu, Jieyuan NingAbstract:Virtual Deep Seismic Sounding (VDSS) has recently emerged as a novel method to image the Moho and potentially other lithospheric boundaries. The behaviour of SsPmp, the post-critical reflection phase at the Moho that is utilized in VDSS, is rich with complexities not yet widely considered. Here, motivated by observations from the Ordos Plateau in North China, we use synthetic seismograms computed with a broad range of 1-D models to evaluate how different parts of the lithosphere along the ray path of SsPmp affect its phase, amplitude and arrival time. Our findings include: (1) When the crust–mantle Boundary is a sharp discontinuity, the SsPmp phase shift relative to the direct S wave is controlled by lower-crustal V_p, upper-mantle V_p and ray parameter. This property indicates the possibility of using SsPmp to constrain V_p in the lower crust and uppermost mantle. (2) When the crust–mantle Boundary is a velocity-gradient zone, SsPmp arrival times vary as different functions of ray parameter from cases with a sharp crust–mantle Boundary, because different rays turn at different depths. This feature allows measurement of the vertical velocity gradient in the crust–mantle transition zone with SsPmp. (3) When the virtual source (location of S-to-P conversion at the free surface) is in a sedimentary basin, SsPmp amplitude can be significantly reduced due to low S-to-P reflected energy at the virtual source. This may cause the absence of SsPmp despite appropriate source–receiver geometry. In addition to 1-D models, we further conduct 2-D waveform modelling and find that the SsPmp arrival time relative to direct S is not only controlled by crustal thickness at the reflection point but also by lateral variation of V_s beneath the virtual source and receiver. Therefore, in areas with significant lateral heterogeneity in the lithosphere the accuracy of crustal-thickness measurements from SsPmp arrival times depends on our knowledge of the variability of lithospheric structure across a broad region.
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Post-critical SsPmp and Its Applications to Virtual Deep Seismic Sounding (VDSS): 1. Sensitivity to Lithospheric 1D and 2D structure
2018Co-Authors: Simon Louis Klemperer, Chunquan Yu, Jieyuan NingAbstract:Virtual Deep Seismic Sounding (VDSS) has recently emerged as a novel method to image the Moho and potentially other lithospheric boundaries. The behavior of SsPmp, the post-critical reflection phase at the Moho that is utilized in VDSS, is rich with complexities not yet widely utilized. Here, motivated by observations from the Ordos Plateau in North China, we use synthetic seismograms computed with a broad range of 1D models to evaluate how different parts of the lithosphere along the ray path of SsPmp affect its phase, amplitude, and arrival time. Our findings include: (1) When the Crust-Mantle Boundary is a sharp discontinuity, the SsPmp phase shift relative to the direct S wave is controlled by lower-crustal Vp, upper-mantle Vp and ray parameter. This property indicates the possibility of using SsPmp to constrain Vp in the lower crust and uppermost mantle. (2) When the Crust-Mantle Boundary is a velocity-gradient zone, SsPmp arrival times vary as different functions of ray parameter from cases with a sharp Crust-Mantle Boundary, because different rays turn at different depths. This feature allows measurement of the vertical velocity gradient in the Crust-Mantle transition zone with SsPmp. (3) When the virtual source (location of S-to-P conversion at the free surface) is in a sedimentary basin, SsPmp amplitude can be significantly reduced due to low S-to-P reflected energy at the virtual source. This may cause the absence of SsPmp despite appropriate source-receiver geometry. In addition to 1D models, we further conduct 2D waveform modeling and find that the SsPmp arrival time relative to direct S is not only controlled by crustal thickness at the reflection point, but also by lateral variation of Vs beneath the virtual source and receiver. Therefore, in areas with significant lateral heterogeneity in the lithosphere the accuracy of crustal-thickness measurements from SsPmp arrival times depends on our knowledge of the variability of lithospheric structure across a broad region.
ALBERTO GALVE - One of the best experts on this subject based on the ideXlab platform.
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Complex images of Moho and variation of Vp/Vs across the Himalaya and South Tibet, from a joint receiver-function and wide-angle-reflection approach
Geophysical Research Letters, 2002Co-Authors: ALBERTO GALVE, J.-c. Lépine, Adriano Hirn, J Diaz, Mireille Laigle, Martine Sapin, Josep GallartAbstract:Teleseismic receiver functions (RF) allow us to image the spatial variation of the Crust-Mantle Boundary (Moho) along a tight array spanning from south of the Himalayas to the centre of the Tibetan Plateau. This approach is cross-tested with wide-angle reflection imaging (WARR). Highlighted by each of the two independent methods, a complex architecture of the Moho with dipping and overlapping segments indicating lithospheric imbrication, is confirmed. The joint use of the two methods reveals an increase of the average crustal P-to-S-wave-velocity ratio from south to the centre of the Lhasa block. This may be due to lowered S-wave velocity confined in specific layers, that may be interpreted as partial melt. This accounts for half of the relative increase in the delay of direct teleseismic S-wave arrivals with respect to P-wave arrivals from south to north, suggesting a similar anomaly in the shallower mantle.
Chunquan Yu - One of the best experts on this subject based on the ideXlab platform.
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Post-critical SsPmp and its Applications to Virtual Deep Seismic Sounding (VDSS)–3: Back-projection Imaging of the Crust-Mantle Boundary in a Heterogeneous Lithosphere
2020Co-Authors: Simon Louis Klemperer, Chunquan Yu, Jieyuan NingAbstract:Virtual Deep Seismic Sounding (VDSS) uses the arrival time of post-critical SsPmp relative to the direct S wave to infer Moho depth at the Pmp reflection point. Due to the large offset between the virtual source and the receiver, SsPmp is more sensitive to lateral variations of structures than near-vertical phases such as Ps that is used to construct conventional P receiver functions. However, the way post-critical SsPmp is affected by lateral variations in lithospheric structures is not well understood, and previous studies largely assumed a 1D structure when analyzing SsPmp waveforms. Here we present synthetic tests with various 2D models to show that lateral variations in lithospheric structures, from the lithosphere-asthenosphere Boundary to sedimentary basins, profoundly affect travel time, phase and amplitude of post-critical SsPmp, and that a 1D approximation is usually inappropriate when analyzing 2D data. Despite these strong effects we show, with synthetic examples and the ChinArray data from the Ordos Block in northern China, that a simple ray-theory-based back-projection method can retrieve the geometry of the Crust-Mantle Boundary given array observations in cases with moderate lateral variations in the Crust-Mantle Boundary and/or the lithosphere-asthenosphere Boundary. The success of our back-projection method indicates that ray-theory approximations are sufficient in modeling SsPmp travel times in the presence of moderate lateral heterogeneity. In contrast, we show that the ray theory is generally insufficient in modeling SsPmp phase shifts in a strongly heterogeneous lithosphere due to non-planar down-going P waves incident at the Crust-Mantle Boundary. Nonetheless, our results demonstrate the feasibility of direct imaging of the Crust-Mantle Boundary with post-critical SsPmp even in the presence of 2D variations of lithospheric structures.
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Post-critical SsPmp and its applications to Virtual Deep Seismic Sounding (VDSS)—1: sensitivity to lithospheric 1-D and 2-D structure
Geophysical Journal International, 2018Co-Authors: Simon Louis Klemperer, Chunquan Yu, Jieyuan NingAbstract:Virtual Deep Seismic Sounding (VDSS) has recently emerged as a novel method to image the Moho and potentially other lithospheric boundaries. The behaviour of SsPmp, the post-critical reflection phase at the Moho that is utilized in VDSS, is rich with complexities not yet widely considered. Here, motivated by observations from the Ordos Plateau in North China, we use synthetic seismograms computed with a broad range of 1-D models to evaluate how different parts of the lithosphere along the ray path of SsPmp affect its phase, amplitude and arrival time. Our findings include: (1) When the crust–mantle Boundary is a sharp discontinuity, the SsPmp phase shift relative to the direct S wave is controlled by lower-crustal V_p, upper-mantle V_p and ray parameter. This property indicates the possibility of using SsPmp to constrain V_p in the lower crust and uppermost mantle. (2) When the crust–mantle Boundary is a velocity-gradient zone, SsPmp arrival times vary as different functions of ray parameter from cases with a sharp crust–mantle Boundary, because different rays turn at different depths. This feature allows measurement of the vertical velocity gradient in the crust–mantle transition zone with SsPmp. (3) When the virtual source (location of S-to-P conversion at the free surface) is in a sedimentary basin, SsPmp amplitude can be significantly reduced due to low S-to-P reflected energy at the virtual source. This may cause the absence of SsPmp despite appropriate source–receiver geometry. In addition to 1-D models, we further conduct 2-D waveform modelling and find that the SsPmp arrival time relative to direct S is not only controlled by crustal thickness at the reflection point but also by lateral variation of V_s beneath the virtual source and receiver. Therefore, in areas with significant lateral heterogeneity in the lithosphere the accuracy of crustal-thickness measurements from SsPmp arrival times depends on our knowledge of the variability of lithospheric structure across a broad region.
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Post-critical SsPmp and Its Applications to Virtual Deep Seismic Sounding (VDSS): 1. Sensitivity to Lithospheric 1D and 2D structure
2018Co-Authors: Simon Louis Klemperer, Chunquan Yu, Jieyuan NingAbstract:Virtual Deep Seismic Sounding (VDSS) has recently emerged as a novel method to image the Moho and potentially other lithospheric boundaries. The behavior of SsPmp, the post-critical reflection phase at the Moho that is utilized in VDSS, is rich with complexities not yet widely utilized. Here, motivated by observations from the Ordos Plateau in North China, we use synthetic seismograms computed with a broad range of 1D models to evaluate how different parts of the lithosphere along the ray path of SsPmp affect its phase, amplitude, and arrival time. Our findings include: (1) When the Crust-Mantle Boundary is a sharp discontinuity, the SsPmp phase shift relative to the direct S wave is controlled by lower-crustal Vp, upper-mantle Vp and ray parameter. This property indicates the possibility of using SsPmp to constrain Vp in the lower crust and uppermost mantle. (2) When the Crust-Mantle Boundary is a velocity-gradient zone, SsPmp arrival times vary as different functions of ray parameter from cases with a sharp Crust-Mantle Boundary, because different rays turn at different depths. This feature allows measurement of the vertical velocity gradient in the Crust-Mantle transition zone with SsPmp. (3) When the virtual source (location of S-to-P conversion at the free surface) is in a sedimentary basin, SsPmp amplitude can be significantly reduced due to low S-to-P reflected energy at the virtual source. This may cause the absence of SsPmp despite appropriate source-receiver geometry. In addition to 1D models, we further conduct 2D waveform modeling and find that the SsPmp arrival time relative to direct S is not only controlled by crustal thickness at the reflection point, but also by lateral variation of Vs beneath the virtual source and receiver. Therefore, in areas with significant lateral heterogeneity in the lithosphere the accuracy of crustal-thickness measurements from SsPmp arrival times depends on our knowledge of the variability of lithospheric structure across a broad region.