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Qi-Fu Chen

Institute of Geology and Geophysics, Key Laboratory of Earth and Planetary Physics, CAS, Faculty Member

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Seismologist
Address: Beijing, Beijing, China

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National & Kapodistrian University of Athens

University of Bristol

Dr. Hadis Samadi Alinia

Western University Canada

Consiglio Nazionale delle Ricerche (CNR)

Atikul Haque Farazi

University of Barisal

STMKG

Washington University in St. Louis

Francisco Velandia

Universidad Industrial de Santander

Ramazan Demirtaş

Ankara University

E. Papadimitriou

Aristotle University of Thessaloniki

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Papers by Qi-Fu Chen

Crust and Uppermost Mantle Magma Plumbing System Beneath Changbaishan Intraplate Volcano, China/North Korea, Revealed by Ambient Noise Adjoint Tomography

Geophysical Research Letters

This dataset contains the original ambient noise cross-correlation data and the final inverted 3D... more This dataset contains the original ambient noise cross-correlation data and the final inverted 3D Vs model for our research paper "Crust and uppermost mantle magma plumbing system beneath Changbaishan intraplate volcano, China/North Korea, revealed by ambient noise adjoint tomography", which has been submitted to Geophysical Research Letters.

Assessment of the site effect of strong ground motion caused by 3 D crustal structure in Beijing area for a scenario earthquake

The three-dimensional (3D) site effect of earthqua ke strong ground motion in Beijing area was as... more The three-dimensional (3D) site effect of earthqua ke strong ground motion in Beijing area was assessed with numerical simulation using the stagge red grid pseudo-spectral time-domain method. The great Sanhe-Pinggu earthquake (M~8, with the ma xi um intensity of XI at the epicenter and VIII in city center of Beijing) is used as the scen ario event in the simulation. The Sanhe-Pinggu earthquake occurred in September 2, 1679 is the lar g st historic event in the past 500 years within a 100-km radius from the center of Beijing. Compreh ension of the ground motion scenario caused by this earthquake will provide valuable informatio n for seismic hazard reduction in the metropolitan Beijing area. The numerical model is c onstructed based on up to date information of the seismogenic Xiadian Fault on which the 1679 M8 event occurred and regional crustal structure model. The simulation results are in fair agreement with the ground motion amplification map in terms of horizontal to vertical s...

Shallow Crustal Response to Arabia‐Eurasia Convergence in Northwestern Iran: Constraints From Multifrequency P‐Wave Receiver Functions

Journal of Geophysical Research: Solid Earth

Distinct Lithospheric Structure in the Xing'an‐Mongolian Orogenic Belt

Geophysical Research Letters

Detailed knowledge of the lithospheric structure is essential for a better understanding of the t... more Detailed knowledge of the lithospheric structure is essential for a better understanding of the tectonic evolution of the Xing'an‐Mongolian Orogenic Belt (XMOB). We constrained the lithospheric structure across the XMOB by receiver function imaging and shear wave splitting analysis from a dense seismic array. The lithosphere‐asthenosphere boundary (LAB) is coherently imaged in different tectonic blocks. The mid‐lithospheric discontinuity is also identified at ∼75–100 km depth over the deeper LAB (∼110–130 km) beneath the western side of the North‐South Gravity Lineament (NSGL), roughly at the same depth as the LAB beneath the eastern side of the NSGL. The distinct variations in both the lithospheric structure and fast shear‐wave polarization direction across the NSGL are likely caused by different tectonic processes in the two sides, indicating that the NSGL might represent the western boundary influenced by the subduction of the (Paleo‐)Pacific Plate. Lithosphere thinning in the XMOB is evidenced to have been limited mainly to the east of the NSGL.

3D topography of mantle transition zone beneath Northeast China ：constraints from receiver function with Ps scattering kernel

Mantle transition zone (MTZ) is the layer between two seismic upper mantle discontinuities, which... more

Upper-mantle shear-wave structure under Asia from Automated Multimode Inversion of waveforms

Japan Geoscience Union, 2015

Crustal Flow beneath Eastern Tibet Revealed by Rayleigh-wave Tomography

Insight Into Major Active Faults in Central Myanmar and the Related Geodynamic Sources

Geophysical Research Letters, 2020

 We detect 854 shallow earthquakes and analyze the focal mechanisms of 40 events based on the da... more  We detect 854 shallow earthquakes and analyze the focal mechanisms of 40 events based on the dataset from a new seismic array in Myanmar.  We identify 2 fault zones in the Central Basin that may accommodate surplus strikeslip deformations not taken up by the Sagaing Fault.  We observe a lower-crustal seismic zone west of the Kabaw Fault, which is controlled by eastward subduction of the Indian Plate.

Layered anisotropy within the crust and lithospheric mantle beneath the Sea of Japan

Journal of Asian Earth Sciences, 2016

Continental rifting during the Oligocene to mid-Miocene caused the opening of the Sea of Japan an... more Continental rifting during the Oligocene to mid-Miocene caused the opening of the Sea of Japan and the separation between the Japanese Islands and the Eurasian Plate. The tectonic evolution in the Sea of Japan is important for understanding the evolution of back-arc regions in active convergent margins. Here, we use data from the seismic stations surrounding the Sea of Japan to map the Rayleigh-wave azimuthal anisotropy in the crust and lithospheric mantle beneath the Sea of Japan. We explore the variations of Rayleigh-wave phase-velocity beneath the Sea of Japan in a broad period range (30-80 s). Rayleighwave dispersion curves are measured by the two-station technique for a total of 231 interstation paths using vertical-component broad-band waveforms at 22 seismic stations around the Sea of Japan from 1411 global earthquakes. The resulting maps of Rayleigh-wave phase velocity and azimuthal anisotropy allow the examination of azimuthal anisotropy at specific periods. They exhibit several regions with different isotropic and anisotropic patterns: the Japan Basin displays fast velocities at shorter periods (30 and 40 s) with NNE-SSW anisotropy, whereas at 60 s and longer, the velocities become slow even if the anisotropy remains NE-SW; the East China Sea shows fast velocities at all periods (30-80 s) with constant NW-SE anisotropy. Trench-normal anisotropy beneath the Japanese Islands is found at short periods (30-40 s) and become trench-parallel at periods of 60 s and longer. Overall, our model resolves two layers of anisotropy, the shallowest and deepest layers being potentially related to frozen deformation due to recent geodynamic events, and asthenospheric flow, respectively.

A viscoelastic model for time-dependent simulating analysis of the Wenchuan earthquake fault

The sudden big earthquake which happened in the Wenchuan county of China in 2008 was an extraordi... more The sudden big earthquake which happened in the Wenchuan county of China in 2008 was an extraordinary type of earthquake. Its exact mechanism is still unknown. The paper presents a simplified computational approach to develop a model to simulate the long-term evolution of the Wenchuan earthquake fault by means of a viscoelastic finite-element method, in order to investigate the dynamic mechanism of the 2008 Wenchuan earthquake. The relevant characteristics of crustal stress fields and displacement fields around the fault are analyzed. It is suggested that the accumulated earthquake energy was mainly due to deep crust motion rather than to surface motion. The study helps show that viscoelastic modeling is a powerful tool for simulating natural phenomena such as crustal movement and its implication for earthquakes.

Distinct slab interfaces imaged within the mantle transition zone

Nature Geoscience, 2020

Anisotropic Rayleigh wave phase velocity maps of eastern China

Journal of Geophysical Research: Solid Earth, 2014

We explore the variations of Rayleigh wave phase velocity beneath eastern China in a broad period... more We explore the variations of Rayleigh wave phase velocity beneath eastern China in a broad period range (20-200 s). Rayleigh wave dispersion curves are measured by the two-station technique for a total of 734 interstation paths using vertical component broadband waveforms at 39 seismic stations in eastern China from 466 global earthquakes. In addition, 599 waveform inversion interstation measurements were added to this data set. The interstation dispersion curves are then inverted for high-resolution isotropic and azimuthally anisotropic phase velocity maps at periods between 20 and 200 s. At shorter periods sampling the crustal depth range, phase velocities are higher in the southeastern part of the region, reflecting the thinner crust there. The Jiangnan Belt separates Cathaysia from the Yangtze Craton, the latter with thicker crust and a deep, high-velocity cratonic root. The eastern part of Yangtze Craton, however, east of 115-116 • E, does not display a deep root and has a thin lithosphere. Azimuthal anisotropy at long periods (>120 s) shows fast propagation directions broadly similar to that of the absolute plate motion. Beneath Cathaysia and eastern Yangtze Craton, anisotropy in the asthenosphere is strong and suggests coast-perpendicular flow. Asthenospheric flow from beneath China's thick continental lithosphere toward the thinner lithosphere of the margin and the resulting decompression melting may be the fundamental causes of the intraplate basaltic volcanism along the eastern coast of China.

Deep deformation of the Longmenshan fault zone related to the 2008 Wenchuan earthquake

Chinese Science Bulletin, 2018

The crustal structures of the central Longmenshan along and its margins as related to the seismot... more

Upper-mantle shear-wave structure under East and Southeast Asia from Automated Multimode Inversion of waveforms

Geophysical Journal International, 2015

We present a new Sv-velocity model of the upper mantle under East and Southeast Asia constrained ... more We present a new Sv-velocity model of the upper mantle under East and Southeast Asia constrained by the inversion of seismic waveforms recorded by broad-band stations. Seismograms from earthquakes occurred between 1977 and 2012 are collected from about 4786 permanent and temporary stations in the region whenever and wherever available. Automated Multimode Inversion of surface and multipleS waveforms is applied to extract structural information from the seismograms, in the form of linear equations with uncorrelated uncertainties. The equations are then solved for the seismic velocity perturbations in the crust and upper mantle with respect to a three-dimensional (3-D) reference model and a realistic crust. Major features of the lithosphere-asthenosphere system in East and Southeast Asia are identified in the resulting model. At lithospheric depth, low velocities can be seen beneath Tibet, whereas high velocities are found beneath cratonic regions, such as the Siberian, North China, Yangtze,) Tarim, and Dharwarand cratons. A number of microplates are mapped and the interaction with neighbouring plates is discussed. Slabs from the Pacific and Indian Oceans can be seen in the upper mantle. Passive marginal basins and subduction zones are also properly resolved.

Slip rate along the Lijiang-Ninglang fault zone estimated from repeating microearthquakes

Chinese Science Bulletin, 2008

D.: Predicting the 1975 Haicheng earthquake

The publicized four-stage (long-term, middle-term, short-term, and im-minent) prediction of the M... more The publicized four-stage (long-term, middle-term, short-term, and im-minent) prediction of the M 7.3 1975 Haicheng, China, earthquake once generated worldwide fascination. Yet the prediction process has remained mysterious because of lack of reports on real-time documentation and details of how warnings were issued. In the present work, study of declassified Chinese documents and interviews of key witnesses have allowed us to reconstruct this important history. Our findings indicate that there were two official middle-term predictions but no official short-term prediction. On the day of the earthquake, a county government issued a specific evacuation order, and actual actions taken by provincial scientists and government officials also effectively constituted an imminent prediction. These efforts saved thousands of lives, but the local construction style and time of the earthquake also contributed to minimizing fatalities. Evacuation was extremely uneven across the disaster region,...

Pntomography with Moho depth correction from eastern Europe to western China

Journal of Geophysical Research: Solid Earth

Increasing background seismicity and dynamic triggering behaviors with nearby mining activities around Fangshan Pluton in Beijing, China

Journal of Geophysical Research: Solid Earth

Dynamic triggering in western Fangshan Pluton, Beijing, China, has been repeatedly identified, bu... more Dynamic triggering in western Fangshan Pluton, Beijing, China, has been repeatedly identified, but previous studies are limited by sparse seismic station coverage. Here we systematically analyze continuous waveforms recorded by both permanent stations and a temporary seismic network 40 days before and after the 11 March 2011 Mw 9.1 Tohoku-Oki and the 14 April 2012 Mw 8.6 Indian Ocean earthquakes. We first build a template database using a short-term average to long-term average method. Next, we apply the matched filter technique that cross correlates the template waveforms with continuous data to detect additional seismic events. Overall, we detect 1956 and 950 seismic events around the Tohoku-Oki and Indian Ocean main shocks, respectively. Most detected events are shallow (<5 km) and clustered at Beiling Syncline in western Fangshan Pluton, which is adjacent to a running coalmine. Seven and 10 events are detected during the large-amplitude surface waves of the two main shocks, respectively, but no similar burst is detected following their major foreshock and aftershocks. Multiple statistical tests indicate that the short-term bursts after the two main shocks are dynamically triggered. We suggest that mining-related activities may perturb the subsurface stress conditions and hence make the region more susceptible for dynamic triggering than other places.

Pnwave geometrical spreading and attenuation in Northeast China and the Korean Peninsula constrained by observations from North Korean nuclear explosions

Journal of Geophysical Research: Solid Earth

We investigate the geometric spreading and attenuation of seismic Pn waves in Northeast China and... more We investigate the geometric spreading and attenuation of seismic Pn waves in Northeast China and the Korean Peninsula. A high-quality broadband Pn wave data set generated by North Korean nuclear tests is used to constrain the parameters of a frequency-dependent log-quadratic geometric spreading function and a power law Pn Q model. The geometric spreading function and apparent Pn wave Q are obtained for Northeast China and the Korean Peninsula between 2.0 and 10.0 Hz. Using the two-station amplitude ratios of the Pn spectra and correcting them with the known spreading function, we remove the contributions of the source and crust from the apparent Pn Q and retrieve the P wave attenuation information along the pure upper mantle path. We then use both Pn amplitudes and amplitude ratios in a tomographic approach to obtain the upper mantle P wave attenuation in the studied area. The Pn wave spectra observed in China are compared with those recorded in Japan, and the result reveals that the high-frequency Pn signal across the oceanic path attenuated faster compared with those through the continental path.

Complicated crustal deformation beneath the NE margin of the Tibetan plateau and its adjacent areas revealed by multi-station receiver-function gathering

Earth and Planetary Science Letters

We use a multi-station stacking method to analyze receiver function data recorded by a large-scal... more We use a multi-station stacking method to analyze receiver function data recorded by a large-scale dense seismic array covering the northeastern (NE) margin of the Tibetan plateau and its adjacent regions to estimate crustal thickness (H), V p/V s ratio (κ) and crustal anisotropy (fast polarization direction ϕ and splitting time τ). For each station of the array, we gathered all the receiver functions recorded by the station and its nearby stations located inside a circle with a radius of 0.5 •. We applied the H−κ stacking technique and the joint inversion scheme to a total of 654 station clusters to measure the (H, κ) and (ϕ, τ), respectively. The measured Moho depth varies from a peak value of 67 km beneath the northern-central plateau to 39-45 km beneath the surrounding blocks in the northeast. The front of the depressed Moho beneath the plateau margin exhibits a complicated geometry, which suggests that when the Tibetan plateau encroached upon the surrounding terranes, the front expanded unevenly depending on the strength of the encountering terranes. The thickened crust beneath the margin also has a very low V p/V s ratio, indicating that the crust is composed largely of felsic minerals. More than one third of the station clusters (221) have a splitting time significantly larger than 0.2 s. The average splitting times of the 221 measurements is 0.68 s, which is comparable to those measured from the SKS/SKKS (XKS) phases (0.94 s). The fast directions estimated from the Moho Ps and XKS phases recorded by the station clusters within the margin are very similar, and are also approximately parallel to the strikes of major faults, sutures and thrust fronts in the area. The low V p/V s ratio, together with the observed fast polarization directions from the Moho Ps and XKS phases, suggests that shortening of the entire lithosphere orthogonal to the compressional direction is likely the main cause for the observed crustal thickening occurring at the margin. We also found that the Moho Ps and XKS recorded by stations inside the western Hetao basin and the Yinchuan basin present very different anisotropy, which may suggest that the crust and mantle beneath the two basins have very different deformation patterns.

Crust and Uppermost Mantle Magma Plumbing System Beneath Changbaishan Intraplate Volcano, China/North Korea, Revealed by Ambient Noise Adjoint Tomography

Geophysical Research Letters

This dataset contains the original ambient noise cross-correlation data and the final inverted 3D... more This dataset contains the original ambient noise cross-correlation data and the final inverted 3D Vs model for our research paper "Crust and uppermost mantle magma plumbing system beneath Changbaishan intraplate volcano, China/North Korea, revealed by ambient noise adjoint tomography", which has been submitted to Geophysical Research Letters.

Assessment of the site effect of strong ground motion caused by 3 D crustal structure in Beijing area for a scenario earthquake

The three-dimensional (3D) site effect of earthqua ke strong ground motion in Beijing area was as... more The three-dimensional (3D) site effect of earthqua ke strong ground motion in Beijing area was assessed with numerical simulation using the stagge red grid pseudo-spectral time-domain method. The great Sanhe-Pinggu earthquake (M~8, with the ma xi um intensity of XI at the epicenter and VIII in city center of Beijing) is used as the scen ario event in the simulation. The Sanhe-Pinggu earthquake occurred in September 2, 1679 is the lar g st historic event in the past 500 years within a 100-km radius from the center of Beijing. Compreh ension of the ground motion scenario caused by this earthquake will provide valuable informatio n for seismic hazard reduction in the metropolitan Beijing area. The numerical model is c onstructed based on up to date information of the seismogenic Xiadian Fault on which the 1679 M8 event occurred and regional crustal structure model. The simulation results are in fair agreement with the ground motion amplification map in terms of horizontal to vertical s...

Shallow Crustal Response to Arabia‐Eurasia Convergence in Northwestern Iran: Constraints From Multifrequency P‐Wave Receiver Functions

Journal of Geophysical Research: Solid Earth

Distinct Lithospheric Structure in the Xing'an‐Mongolian Orogenic Belt

Geophysical Research Letters

Detailed knowledge of the lithospheric structure is essential for a better understanding of the t... more Detailed knowledge of the lithospheric structure is essential for a better understanding of the tectonic evolution of the Xing'an‐Mongolian Orogenic Belt (XMOB). We constrained the lithospheric structure across the XMOB by receiver function imaging and shear wave splitting analysis from a dense seismic array. The lithosphere‐asthenosphere boundary (LAB) is coherently imaged in different tectonic blocks. The mid‐lithospheric discontinuity is also identified at ∼75–100 km depth over the deeper LAB (∼110–130 km) beneath the western side of the North‐South Gravity Lineament (NSGL), roughly at the same depth as the LAB beneath the eastern side of the NSGL. The distinct variations in both the lithospheric structure and fast shear‐wave polarization direction across the NSGL are likely caused by different tectonic processes in the two sides, indicating that the NSGL might represent the western boundary influenced by the subduction of the (Paleo‐)Pacific Plate. Lithosphere thinning in the XMOB is evidenced to have been limited mainly to the east of the NSGL.

3D topography of mantle transition zone beneath Northeast China ：constraints from receiver function with Ps scattering kernel

Mantle transition zone (MTZ) is the layer between two seismic upper mantle discontinuities, which... more

Upper-mantle shear-wave structure under Asia from Automated Multimode Inversion of waveforms

Japan Geoscience Union, 2015

Crustal Flow beneath Eastern Tibet Revealed by Rayleigh-wave Tomography

Insight Into Major Active Faults in Central Myanmar and the Related Geodynamic Sources

Geophysical Research Letters, 2020

 We detect 854 shallow earthquakes and analyze the focal mechanisms of 40 events based on the da... more  We detect 854 shallow earthquakes and analyze the focal mechanisms of 40 events based on the dataset from a new seismic array in Myanmar.  We identify 2 fault zones in the Central Basin that may accommodate surplus strikeslip deformations not taken up by the Sagaing Fault.  We observe a lower-crustal seismic zone west of the Kabaw Fault, which is controlled by eastward subduction of the Indian Plate.

Layered anisotropy within the crust and lithospheric mantle beneath the Sea of Japan

Journal of Asian Earth Sciences, 2016

Continental rifting during the Oligocene to mid-Miocene caused the opening of the Sea of Japan an... more Continental rifting during the Oligocene to mid-Miocene caused the opening of the Sea of Japan and the separation between the Japanese Islands and the Eurasian Plate. The tectonic evolution in the Sea of Japan is important for understanding the evolution of back-arc regions in active convergent margins. Here, we use data from the seismic stations surrounding the Sea of Japan to map the Rayleigh-wave azimuthal anisotropy in the crust and lithospheric mantle beneath the Sea of Japan. We explore the variations of Rayleigh-wave phase-velocity beneath the Sea of Japan in a broad period range (30-80 s). Rayleighwave dispersion curves are measured by the two-station technique for a total of 231 interstation paths using vertical-component broad-band waveforms at 22 seismic stations around the Sea of Japan from 1411 global earthquakes. The resulting maps of Rayleigh-wave phase velocity and azimuthal anisotropy allow the examination of azimuthal anisotropy at specific periods. They exhibit several regions with different isotropic and anisotropic patterns: the Japan Basin displays fast velocities at shorter periods (30 and 40 s) with NNE-SSW anisotropy, whereas at 60 s and longer, the velocities become slow even if the anisotropy remains NE-SW; the East China Sea shows fast velocities at all periods (30-80 s) with constant NW-SE anisotropy. Trench-normal anisotropy beneath the Japanese Islands is found at short periods (30-40 s) and become trench-parallel at periods of 60 s and longer. Overall, our model resolves two layers of anisotropy, the shallowest and deepest layers being potentially related to frozen deformation due to recent geodynamic events, and asthenospheric flow, respectively.

A viscoelastic model for time-dependent simulating analysis of the Wenchuan earthquake fault

The sudden big earthquake which happened in the Wenchuan county of China in 2008 was an extraordi... more The sudden big earthquake which happened in the Wenchuan county of China in 2008 was an extraordinary type of earthquake. Its exact mechanism is still unknown. The paper presents a simplified computational approach to develop a model to simulate the long-term evolution of the Wenchuan earthquake fault by means of a viscoelastic finite-element method, in order to investigate the dynamic mechanism of the 2008 Wenchuan earthquake. The relevant characteristics of crustal stress fields and displacement fields around the fault are analyzed. It is suggested that the accumulated earthquake energy was mainly due to deep crust motion rather than to surface motion. The study helps show that viscoelastic modeling is a powerful tool for simulating natural phenomena such as crustal movement and its implication for earthquakes.

Distinct slab interfaces imaged within the mantle transition zone

Nature Geoscience, 2020

Anisotropic Rayleigh wave phase velocity maps of eastern China

Journal of Geophysical Research: Solid Earth, 2014

We explore the variations of Rayleigh wave phase velocity beneath eastern China in a broad period... more We explore the variations of Rayleigh wave phase velocity beneath eastern China in a broad period range (20-200 s). Rayleigh wave dispersion curves are measured by the two-station technique for a total of 734 interstation paths using vertical component broadband waveforms at 39 seismic stations in eastern China from 466 global earthquakes. In addition, 599 waveform inversion interstation measurements were added to this data set. The interstation dispersion curves are then inverted for high-resolution isotropic and azimuthally anisotropic phase velocity maps at periods between 20 and 200 s. At shorter periods sampling the crustal depth range, phase velocities are higher in the southeastern part of the region, reflecting the thinner crust there. The Jiangnan Belt separates Cathaysia from the Yangtze Craton, the latter with thicker crust and a deep, high-velocity cratonic root. The eastern part of Yangtze Craton, however, east of 115-116 • E, does not display a deep root and has a thin lithosphere. Azimuthal anisotropy at long periods (>120 s) shows fast propagation directions broadly similar to that of the absolute plate motion. Beneath Cathaysia and eastern Yangtze Craton, anisotropy in the asthenosphere is strong and suggests coast-perpendicular flow. Asthenospheric flow from beneath China's thick continental lithosphere toward the thinner lithosphere of the margin and the resulting decompression melting may be the fundamental causes of the intraplate basaltic volcanism along the eastern coast of China.

Deep deformation of the Longmenshan fault zone related to the 2008 Wenchuan earthquake

Chinese Science Bulletin, 2018

The crustal structures of the central Longmenshan along and its margins as related to the seismot... more

Upper-mantle shear-wave structure under East and Southeast Asia from Automated Multimode Inversion of waveforms

Geophysical Journal International, 2015

We present a new Sv-velocity model of the upper mantle under East and Southeast Asia constrained ... more We present a new Sv-velocity model of the upper mantle under East and Southeast Asia constrained by the inversion of seismic waveforms recorded by broad-band stations. Seismograms from earthquakes occurred between 1977 and 2012 are collected from about 4786 permanent and temporary stations in the region whenever and wherever available. Automated Multimode Inversion of surface and multipleS waveforms is applied to extract structural information from the seismograms, in the form of linear equations with uncorrelated uncertainties. The equations are then solved for the seismic velocity perturbations in the crust and upper mantle with respect to a three-dimensional (3-D) reference model and a realistic crust. Major features of the lithosphere-asthenosphere system in East and Southeast Asia are identified in the resulting model. At lithospheric depth, low velocities can be seen beneath Tibet, whereas high velocities are found beneath cratonic regions, such as the Siberian, North China, Yangtze,) Tarim, and Dharwarand cratons. A number of microplates are mapped and the interaction with neighbouring plates is discussed. Slabs from the Pacific and Indian Oceans can be seen in the upper mantle. Passive marginal basins and subduction zones are also properly resolved.

Slip rate along the Lijiang-Ninglang fault zone estimated from repeating microearthquakes

Chinese Science Bulletin, 2008

D.: Predicting the 1975 Haicheng earthquake

The publicized four-stage (long-term, middle-term, short-term, and im-minent) prediction of the M... more The publicized four-stage (long-term, middle-term, short-term, and im-minent) prediction of the M 7.3 1975 Haicheng, China, earthquake once generated worldwide fascination. Yet the prediction process has remained mysterious because of lack of reports on real-time documentation and details of how warnings were issued. In the present work, study of declassified Chinese documents and interviews of key witnesses have allowed us to reconstruct this important history. Our findings indicate that there were two official middle-term predictions but no official short-term prediction. On the day of the earthquake, a county government issued a specific evacuation order, and actual actions taken by provincial scientists and government officials also effectively constituted an imminent prediction. These efforts saved thousands of lives, but the local construction style and time of the earthquake also contributed to minimizing fatalities. Evacuation was extremely uneven across the disaster region,...

Pntomography with Moho depth correction from eastern Europe to western China

Journal of Geophysical Research: Solid Earth

Increasing background seismicity and dynamic triggering behaviors with nearby mining activities around Fangshan Pluton in Beijing, China

Journal of Geophysical Research: Solid Earth

Dynamic triggering in western Fangshan Pluton, Beijing, China, has been repeatedly identified, bu... more Dynamic triggering in western Fangshan Pluton, Beijing, China, has been repeatedly identified, but previous studies are limited by sparse seismic station coverage. Here we systematically analyze continuous waveforms recorded by both permanent stations and a temporary seismic network 40 days before and after the 11 March 2011 Mw 9.1 Tohoku-Oki and the 14 April 2012 Mw 8.6 Indian Ocean earthquakes. We first build a template database using a short-term average to long-term average method. Next, we apply the matched filter technique that cross correlates the template waveforms with continuous data to detect additional seismic events. Overall, we detect 1956 and 950 seismic events around the Tohoku-Oki and Indian Ocean main shocks, respectively. Most detected events are shallow (<5 km) and clustered at Beiling Syncline in western Fangshan Pluton, which is adjacent to a running coalmine. Seven and 10 events are detected during the large-amplitude surface waves of the two main shocks, respectively, but no similar burst is detected following their major foreshock and aftershocks. Multiple statistical tests indicate that the short-term bursts after the two main shocks are dynamically triggered. We suggest that mining-related activities may perturb the subsurface stress conditions and hence make the region more susceptible for dynamic triggering than other places.

Pnwave geometrical spreading and attenuation in Northeast China and the Korean Peninsula constrained by observations from North Korean nuclear explosions

Journal of Geophysical Research: Solid Earth

We investigate the geometric spreading and attenuation of seismic Pn waves in Northeast China and... more We investigate the geometric spreading and attenuation of seismic Pn waves in Northeast China and the Korean Peninsula. A high-quality broadband Pn wave data set generated by North Korean nuclear tests is used to constrain the parameters of a frequency-dependent log-quadratic geometric spreading function and a power law Pn Q model. The geometric spreading function and apparent Pn wave Q are obtained for Northeast China and the Korean Peninsula between 2.0 and 10.0 Hz. Using the two-station amplitude ratios of the Pn spectra and correcting them with the known spreading function, we remove the contributions of the source and crust from the apparent Pn Q and retrieve the P wave attenuation information along the pure upper mantle path. We then use both Pn amplitudes and amplitude ratios in a tomographic approach to obtain the upper mantle P wave attenuation in the studied area. The Pn wave spectra observed in China are compared with those recorded in Japan, and the result reveals that the high-frequency Pn signal across the oceanic path attenuated faster compared with those through the continental path.

Complicated crustal deformation beneath the NE margin of the Tibetan plateau and its adjacent areas revealed by multi-station receiver-function gathering

Earth and Planetary Science Letters

We use a multi-station stacking method to analyze receiver function data recorded by a large-scal... more We use a multi-station stacking method to analyze receiver function data recorded by a large-scale dense seismic array covering the northeastern (NE) margin of the Tibetan plateau and its adjacent regions to estimate crustal thickness (H), V p/V s ratio (κ) and crustal anisotropy (fast polarization direction ϕ and splitting time τ). For each station of the array, we gathered all the receiver functions recorded by the station and its nearby stations located inside a circle with a radius of 0.5 •. We applied the H−κ stacking technique and the joint inversion scheme to a total of 654 station clusters to measure the (H, κ) and (ϕ, τ), respectively. The measured Moho depth varies from a peak value of 67 km beneath the northern-central plateau to 39-45 km beneath the surrounding blocks in the northeast. The front of the depressed Moho beneath the plateau margin exhibits a complicated geometry, which suggests that when the Tibetan plateau encroached upon the surrounding terranes, the front expanded unevenly depending on the strength of the encountering terranes. The thickened crust beneath the margin also has a very low V p/V s ratio, indicating that the crust is composed largely of felsic minerals. More than one third of the station clusters (221) have a splitting time significantly larger than 0.2 s. The average splitting times of the 221 measurements is 0.68 s, which is comparable to those measured from the SKS/SKKS (XKS) phases (0.94 s). The fast directions estimated from the Moho Ps and XKS phases recorded by the station clusters within the margin are very similar, and are also approximately parallel to the strikes of major faults, sutures and thrust fronts in the area. The low V p/V s ratio, together with the observed fast polarization directions from the Moho Ps and XKS phases, suggests that shortening of the entire lithosphere orthogonal to the compressional direction is likely the main cause for the observed crustal thickening occurring at the margin. We also found that the Moho Ps and XKS recorded by stations inside the western Hetao basin and the Yinchuan basin present very different anisotropy, which may suggest that the crust and mantle beneath the two basins have very different deformation patterns.