Search

SUMMERYDue to the far-field effect of the India–Eurasia collision, the Tien Shan orogenic belt has been undergoing reactivation and modification. Two end-member models of the geodynamic mechanisms are (1) surface uplift due to crustal shortening caused by lithospheric compression and (2) mountain formation resulting from thermal upwelling of asthenospheric mantle materials generated by lithospheric subduction. However, the topography along the Tien Shan orogenic belt changes significantly, and the deep structure and dynamic process are quite different beneath the Tien Shan orogenic belt from both geological and geophysical observations. Therefore, the reactivation and modification of the Tien Shan orogenic belt are likely influenced by both geodynamic mechanisms, which also generate various thermal anomalies in the crust. Seismic Lg-wave attenuation is very sensitive to crustal material composition and status and can point to the presence of partial melting within the crust resulting from mantle upwelling. In this study, we develop a high-resolution Lg-wave attenuation model between 0.05 and 10.0 Hz in Northwest China and use lateral attenuation variations to infer thermal structures in the crust. The central Tien Shan is characterized by prominent low-QLg anomalies, whereas relatively high-QLg distributions are imaged beneath the eastern and western Tien Shan. The surface uplift and crustal deformation are mostly related to the upwelling of hot mantle materials in the central Tien Shan and are likely induced by lithospheric compression in the eastern and western Tien Shan. However, low-Q anomalies are observed in the junction between the Pamir Plateau and western Tien Shan, indicating that the uplift in the south of the western Tien Shan is related to thermal subduction-induced upwelling and intrusion into the crust due to the collision between the Indian and Eurasian plates. The Kazakh Shield, characterized by pronounced high-QLg values, is likely a cold and hard terrane, and hence blocks the far-field effect of the India–Eurasia collision.

We investigate the 4 August 2020 Beirut accidental chemical explosion based on regional seismic data recorded at both on- and off-shore stations. The Lg-wave body-wave magnitude is mb(Lg)=3.30±0.46 for the Beirut explosion. The explosive yield obtained using an empirical magnitude-yield relation based on a fully buried explosion source model is only 0.112 kt. Alternatively, the yield estimated using an empirical relation between the yield and crater size is 1.22 kt, with the uncertainties between 0.48 and 2.3 kt. The latter is closer to reality. The P/S spectral amplitude ratios, including Pg/Lg, Pn/Lg, and Pn/Sn, are calculated for the Beirut explosion and nearby natural earthquakes. We find the P/S spectral ratios are effective in discriminating the explosion from earthquakes in the Northwestern Arabia plate. By comparing the spectral ratios of large open-pit explosions, including the Beirut, Xiangshui, and Tianjin explosions, with those from historical nuclear explosions, buried small chemical explosions, and natural earthquakes, we further investigate the detailed differences of network-averaged P/S spectral ratios between different source types.

SUMMARY On 2019 March 21, an explosion accidentally occurred at a chemical plant in Xiangshui, Yancheng City, Jiangsu Province, China. Using broad-band digital seismic data from East China, South Korea and Japan, we investigate properties of the Xiangshui explosion as well as two nearby chemical explosions and four nearby natural earthquakes in Jiangsu Province, East China. From Lg and Rayleigh waves recorded by regional networks, both body wave magnitude mb (Lg) and surface wave magnitude Ms (Rayleigh) are calculated for these events. The magnitudes of the Xiangshui explosion are mb (Lg) = 3.39 ± 0.24 and Ms = 1.95 ± 0.27, respectively. Both the empirical magnitude–yield relation for buried explosion and empirical yield–crater dimension relation for open-pit explosion are adopted for investigating the explosive yield. The result from the yield–crater dimension relation is approximately 492 ton, which is consistent with the ground truth and considerably larger than that from the buried source model. This also reveals that, for Xiangshui explosion, the explosion to seismic energy conversion rate is approximately one-third compared to a similar sized fully confined explosion. By comparing the body wave and surface wave magnitudes from explosions and nearby earthquakes, we find that the mb:Ms discriminant calculated at regional distances cannot properly distinguish explosions from natural earthquakes. However, the P/S spectral ratios Pg/Lg, Pn/Lg and Pn/Sn from the same data set can be good discriminants for identifying explosions from earthquakes.

SUMMARYThe crustal attenuation structure can effectively reveal the rheology and thermal properties of different geological blocks, and can provide seismological constraints on regional tectonic evolution. Based on 11 306 vertical-component Lg-wave seismograms recorded at 111 broad-band stations from 891 crustal earthquakes that occurred between 1994 and 2020, a broad-band Lg-wave attenuation model is obtained for Southeast Asia. This study demonstrates the capability of applying crustal Lg-wave attenuation inversion in a complex region mixed with continents, islands and marginal seas. The resolution approaches 2° in most parts in the study region. Lg blockages are observed at places with sharp Moho depth changes. The resultant Q models are consistent with regional geologic structures provided by previous studies. Prominent low-attenuation anomalies are located in the Sundaland Core containing stable ancient crust, including Indochina, Malay Peninsula, East Sumatra, Sunda Shelf and Borneo Core. Regions with strong attenuation are associated with complex tectonic conditions, such as the Indo–Australian subduction zone, sutures in Sarawak and Sabah. The observed Lg-wave attenuation characteristics provide constraints on the tectonic affinities and evolutions of the geological blocks. The results show that the Borneo Core remained stable since its accretion with the Sundaland Core. Ancient blocks are characterized by weak Lg attenuation, whereas geologically younger terranes are often characterized by strong Lg attenuation, which can be exploited to better understand the separation and convergence of plates during the tectonic evolution.

We have developed an optimal method to determine expansion parameters for flexible stencils in 2D scalar-wave finite-difference frequency-domain (FDFD) simulation. Our stencil only requires the involved grid points to be paired and rotationally symmetric around the central point. We apply this method to the transition zone in discontinuous-grid modeling, in which the key issue is designing particular FDFD stencils to correctly propagate the wavefield passing through the discontinuous interface. Our method can work in an FDFD discontinuous grid with arbitrary integer coarse- to fine-grid spacing ratios. Numerical examples are developed to determine how to apply this optimal method to discontinuous-grid FDFD schemes with spacing ratios of 3 and 5. The synthetic wavefields are highly consistent to those calculated using the conventional dense uniform grid, and the memory requirement and computational costs are greatly reduced. For velocity models with large contrasts, our discontinuous-grid FDFD method can significantly improve the computational efficiency in forward modeling, imaging, and full-waveform inversion.

The applicability of the empirical magnitude–yield relations developed for northeast China and Korean Peninsula explosions was investigated for data from northwest China. We collected regional broadband digital seismic data from 13 chemical explosions (CEx) detonated between 6 September and 10 October 2018, on the eastern margin of the Junggar basin, northwest China, five nuclear tests at the Semipalatinsk nuclear test site, and eight natural earthquakes. Both Lg and Rayleigh-wave magnitudes (mb(Lg) and Ms, respectively) were estimated for these events. Similar to the North Korean test site, the mb(Lg)–Ms discriminant did not properly distinguish explosions from natural earthquakes at the Semipalatinsk test site. However, network-averaged P/S spectral ratios (Pg/Lg, Pn/Lg, and Pn/Sn) did successfully discriminate explosions from earthquakes at both the North Korean and the Semipalatinsk test sites at frequencies above 2.0 Hz. Based on 13 known-yield CEx, we selected an empirical magnitude–yield relation to constrain the explosive yields of five historical nuclear tests at the Semipalatinsk test site. The resulting yields are lower than those previously obtained from teleseismic observations.

The discontinuous-grid method can greatly reduce the storage requirement and computational cost in finite-difference modeling, especially for models with large velocity contrasts. However, this technique is mostly applied to time-domain methods. We have developed a discontinuous-grid finite-difference scheme for frequency-domain 2D scalar wave modeling. Special frequency-domain finite-difference stencils are designed in the fine-coarse grid transition zone. The coarse-to-fine-grid spacing ratio is restricted to [Formula: see text], where [Formula: see text] is a positive integer. Optimization equations are formulated to obtain expansion coefficients for irregular stencils in the transition zone. The proposed method works well when teamed with commonly used 9- and 25-point schemes. Compared with the conventional frequency-domain finite-difference method, the proposed discontinuous-grid method can largely reduce the size of the impedance matrix and number of nonzero elements. Numerical experiments demonstrated that the proposed discontinuous-grid scheme can significantly reduce memory and computational costs, while still yielding almost identical results compared with those from conventional uniform-grid simulations. When tested for a very long elapsed time, the frequency-domain discontinuous-grid method does not show instability problems as its time-domain counterpart usually does.

The seismological characteristics of the 15 February 2013 Chelyabinsk bolide explosion are investigated based on seismograms recorded at 50 stations with epicentral distances ranging from 229 to 4324 km. By using 8–25 s vertical-component Rayleigh waveforms, we obtain a surface-wave magnitude of 4.17±0.31 for this event. According to the relationship among the Rayleigh-wave magnitude, burst height and explosive yield, the explosion yield is estimated to be 686 kt. Using a single-force source to fit the observed Rayleigh waveforms, we obtain a single force of 1.03×1012 N, which is equivalent to the impact from the shock wave generated by the bolide explosion.

At 11:30 on September 3, 2017 (Beijing time), a strong earthquake occurred in Democratic People′s Republic of Korea (DPRK). International seismic monitoring agencies, e.g., the China Earthquake Network Center (CENC) and the United States Geological Survey, suspected that it is an explosion. Based on seismic data from the China National Digital Seismic Network (CNDSN) and Global Seismic Network (GSN), we investigated characteristics of this event and an aftershock 8 min after the main event. The P- and S-wave excitation functions of explosion and earthquake sources are scaled differently. Therefore, the P/S-type spectral ratios can be an effective discriminant for separating explosions from earthquakes. Using the P/S spectral ratios Pg/Lg, Pn/Lg and Pn/Sn as discriminants, we confirmed the 3 September 2017 event was an explosion. For the aftershock occurred after the main event, we identified it is a collapse, likely caused by the failure of the explosion generated cavity. Using a pre-calibrated regional seismic network in Northeast China and the Korean peninsula, and the regional Lg-wave attenuation model developed previously, we obtained the Lg wave body wave magnitudes for the 3 September 2017 main event and its aftershock to be m b(Lg)=5.6±0.2, and 3.95±0.04. We used a group of historical events to calibrate the regional network for calculating Rayleigh wave magnitude. After correcting for the site responses, the network averaged surface wave magnitudes for the main shock and the aftershock were obtained to be M s=5.1±0.2 and 3.95±0.08. To test body-wave versus surface-wave magnitude as a potential discriminant, we compared the M s (Rayleigh) and m b (Lg) for all 6 DPRK nuclear explosions and a group of earthquakes in Northeast China and the Korean peninsula. The explosion and earthquake populations were largely overlapped with each other. The above results show that the P/S ratio method is a more effective discriminant than the m b(Lg)- M s criterion in Northeast China and the Korean Peninsula. The seismic yield of an underground nuclear explosion can be estimated from its magnitude using a calibrated empirical magnitude-yield relation. However, the DPRK test site (DPRKTS) is an uncalibrated test site. Considering that the DPRKTS is located at a granite site in a stable geology platform, we adopted the fully-coupled hard-rock site equation used at the Novaya Zemlya test site to calculate the yield at the DPRKTS. The estimated yield for the 3 September 2017 explosion was 56 kt using this relationship and assuming a normally scaled burial depth. Transferring the measurement error of ±0.2 magnitude unit to the yield calculation introduced uncertainties between 30 and 100 kt. However, if the explosion was over buried at depths between 1000 and 2400 m, the yield could be increased to 100–200 kt.

We characterize the seismic events that occurred in North Korea on 9 September 2016 and South Korea on 12 September 2016. The 9 September 2016 event was identified as an explosion, and the two 12 September 2016 events were identified as natural earthquakes using the P/S (P-and S-wave) spectral ratios, Pg/Lg, Pn/Lg, and Pn/Sn as discriminants. The explosive event was relocated within the North Korean nuclear test site using a relative location method and the 2006 North Korea underground nuclear test as the master event, and the epicenter was identified at 41.2976 degrees N latitude and 129.0804 degrees E longitude. From the regional Lg and Rayleigh waves, the body-and surface-wave magnitudes for the 9 September 2016 event were calculated as m(b) (Lg) = 4: 8 +/- 0: 2 and M-s = 4: 2 +/- 0: 1. By adopting an empirical magnitude-yield relation for the body-wave magnitude, and assuming that the explosion was fully coupled and detonated at a normally scaled depth, we estimated that the seismic yield was similar to 6 kt, and the uncertainty range was between 3 and 11 kt. If an overburied depth range between 780 and 1200 m was applied, then the yield would be increased to 16-22 kt.

We estimate the Lg-wave quality factor (Q) across the Australian continent from vertical-component Lg waveforms. A tomographic inversion is performed to construct an Lg attenuation model for 58 frequencies between 0.05 and 10.0 Hz. The available spatial resolution is approximately 1.5° × 1.5° for the 0.5–2.0 Hz band. At 1.0 Hz, the Lg-wave Q over the whole island continent varies from 50 to 1250 with an average value of 850. Significant regional variations in the Lg-wave Q images tie well with many geological features and boundaries in Australia. The cratons in western, northern and southern parts of Australia usually have higher Q values (700–1250), while the volcanic regions, sedimentary basins and orogenic areas in eastern Australia are characterized by increased attenuation (lower Q values, 50–650). We determine the frequency-dependent Q of Lg waves for different blocks across Australia, and find the frequency dependence of Q is much more complex than the traditional single power law representation. When combined with the assumed geometrical spreading relation, the Lg Q maps provide a new way of assessing potential ground motion across the continent for any event location.

We have developed a general optimal method for 2D frequency-domain finite-difference simulation of the scalar wave equation. For a given finite-difference stencil, this method can generate the dispersion equation and optimize the expansion coefficients. Many commonly used frequency-domain finite-difference schemes (e.g., grids with different numbers of points, rotated grids, and grid spaces with different aspect ratios) can be derived as special cases under this framework. The possibility of expanding this method to 3D does exist. Based on the 2D scalar wave equation, the optimized coefficients of 25-point, 9-point, 17-point, and 15-point schemes have been worked out. The dispersion analysis indicates that our 25-point scheme has much higher accuracy than the average-derivative method 25-point scheme. The number of grid points per the smallest wavelength is reduced from 2.78 to 2.13 for a maximum phase velocity errors of 1%. The synthetic seismograms and the wavefield snapshots calculated using our optimal 25-point finite-different scheme give smaller dispersions than other finite-difference schemes.

Seismology plays an important role in characterizing potential underground nuclear tests. Using broad-band digital seismic data from Northeast China, South Korea and Japan, we investigated the properties of the recent seismic event occurred in North Korea on 2016 January 6. Using a relative location method and choosing the previous 2006 explosion as the master event, the 2016 event was located within the North Korean nuclear test site, with its epicentre at latitude 41.3003°N and longitude 129.0678°E, approximately 900 m north and 500 m west of the previous event on 2013 February 12. Based on the error ellipse, the relocation uncertainty was approximately 70 m. Using the P/S spectral ratios, including Pg/Lg, Pn/Lg and Pn/Sn, as the discriminants, we identify the 2016 event as an explosion rather than an earthquake. The body-wave magnitude calculated from regional wave Lg is mb(Lg) equal to 4.7 ± 0.2. Adopting an empirical magnitude–yield relation, and assuming that the explosion is fully coupled and detonated at a normally scaled depth, we find that the seismic yield is about 4 kt, with the uncertainties allowing a range from 2 to 8 kt.

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.

Online Material: Figures of Pn waveform comparisons and spectral ratios; tables of Pn differential times and parameters for events used in the study. On 12 February 2013, North Korea conducted its third and the largest nuclear test to date in the China–North Korea border area. According to local news, people living in nearby Chinese cities experienced shaking from this explosion. The U.S. Geological Survey (USGS) reported the explosion was located at (41.301° N, 129.066° E) and the magnitude was M 5.1. This event trigged abundant regional seismic phases in northeast China, Korea, and Japan. Because of its large magnitude, the seismic records from this event showed better signal‐to‐noise ratios than those from previous two nuclear explosions. Illustrated in Figure 1 are broadband regional seismograms at station MDJ for three North Korea nuclear tests. These waveforms are highly similar, all are featured with abrupt P ‐wave arrivals, weak Lg phases and well‐developed short‐period Rayleigh waves. We collect the regional waveforms recorded on China National Digital Seismic Network (CNDSN), Global Seismic Network (GSN), and Japan F‐net to investigate the 12 February 2013 North Korean nuclear test. Figure 1. Seismograms recorded on MDJ from three North Korean nuclear tests in 2013, 2009, and 2006. Illustrated are normalized vertical displacements. The event date, maximum amplitudes, and epicenter distances are listed on the left. Marks on the waveforms indicate apparent group velocities. Note that the waveforms show similar features and display clear impulsive P ‐wave onset, relatively weak Lg phases, and 3–5 s period Rayleigh waves. ### High‐Precision Location By adopting the relative location method (e.g., Schaff and Richards, 2004; Zhang et al. , 2005; Wen and Long, 2010; Murphy et al. , 2013), and using the first North Korean nuclear test on 9 October 2006 as the master event, we calculate the origin times and locations of the 25 May 2009 and …

As a prominent geophysical anomaly, unusually high seismic wave attenuation is observed in the crust and upper mantle of the Tibetan Plateau, particularly along its northern area. Theoretical and laboratory investigations show that the strong seismic attenuation can indicate high temperatures and partial melting, which may decrease the viscosity of the material and cause it to flow. Thus, seismic attenuation distribution may provide useful constraints to the crust flows if they exist. Using Lg-wave Q tomography, we construct a 0.05–10.0 Hz broadband high-resolution crust attenuation model for the Tibetan Plateau and its surrounding regions. The maximum spatial resolution is approximately 1.0 ° × 1.0 ° in well-covered areas and for frequencies between 0.05 and 1.5 Hz. This attenuation model reveals an apparent low-QLg belt stretching along the northern and eastern Tibetan plateau. Combining the Lg-wave Q model with other geophysical data, two possible crust flow channels are found in the Tibetan Plateau. The main flow channel is from north to east and then turns to southeastern Tibet along the western edge of the rigid Sichuan basin, while a second channel starts from southern Tibet and crosses the Eastern Himalayan syntaxis.

Lian-Feng Zhao,1,2 Xiao-Bi Xie,2 Wei-Min Wang,3 Jin-Hai Zhang1 and Zhen-Xing Yao1 1Key Laboratory of the Earth’s Deep Interior, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, China. E-mail: zhaolf@mail.iggcas.ac.cn 2Institute of Geophysics and Planetary Physics, University of California, Santa Cruz, CA 95064, USA 3Key Laboratory of Continental Collision and Plateau Uplift, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, China

The seismic waveforms would be clipped when the amplitude exceeds the upper-limit dynamic range of seismometer. Clipped waveforms are typically assumed not useful and seldom used in waveform-based research. Here, we assume the clipped components of the waveform share the same frequency content with the un-clipped components. We leverage this similarity to convert clipped waveforms to true waveforms by iteratively reconstructing the frequency spectrum using the projection onto convex sets method. Using artificially clipped data we find that statistically the restoration error is ~1% and ~5% when clipped at 70% and 40% peak amplitude, respectively. We verify our method using real data recorded at co-located seismometers that have different gain controls, one set to record large amplitudes on scale and the other set to record low amplitudes on scale. Using our restoration method we recover 87 out of 93 clipped broadband records from the 2013 Mw6.6 Lushan earthquake. Estimating that we recover 20 clipped waveforms for each M5.0+ earthquake, so for the ~1,500 M5.0+ events that occur each year we could restore ~30,000 clipped waveforms each year, which would greatly enhance useable waveform data archives. These restored waveform data would also improve the azimuthal station coverage and spatial footprint.

This thesis takes archives management system of Huzhou Teachers College which the author has participated in its development when working in the archive as an example, and briefly introduces the system architecture and function module of archives management system in high education based on B/S model and ASP technology, which greatly raises network level of file query and management efficiency in colleges and university.

VLAN technology refers to the virtual local area network technology, which is classifyd into several network segments in logic through the internal devices of existing LAN, rather than physical location, so as to realize a computer network technology of virtual working group. This paper analyzes and studies on the generation, characteristics, and communication method of VLAN technology, as well as its actual application and setting.

Semi steel radial tire for passenger car needs to be classified and palletized after dynamic balance and uniformity test, in order to store in the finished product warehouse. In view of the present situation that tire's classification and palletizing remains to manual operation, a kind of automatic classification and palletizing manipulator which is used for passenger car tire after dynamic balance and uniformity test has been researched and designed. This paper introduces the manipulator's composition and the manipulator's three dimensional CAD models have been established in SolidWorks platform.

In this paper the object of study is automatic sorting and palletizing manipulator for passenger car tire. It designed the driving mechanism and control system of the manipulator. There are 3 degrees of freedom with the automatic sorting and palletizing manipulator in this paper. The horizontal and vertical movement of manipulator's movable parts is drived by servo motor. And manipulator's gripper grabs and places tires by cylinder drive. In addition, the centering device opens or tightens 4 embraced arms by cylinder drive. A touch-screen is used as the man-machine interface, which can represent manipulator's operation process and results. Realizing the control of the manipulator by PLC combined with the corresponding software programming.

We collect nine vertical component broadband seismograms from the 25 May 2009 North Korean nuclear explosion for a regional seismic network in which eight stations also recorded the 9 October 2006 North Korean nuclear test. Comparing the observed waveforms and spectra from the two events, we estimate that the amplitudes of the records from the second event are approximately five times those from the first one. Additionally, we use 599 vertical broadband seismograms from 82 regional events recorded on the regional network between December 1995 and May 2009 to calibrate the network Lg ‐wave magnitude. The calibrated network is used to calculate the Lg ‐wave body‐wave magnitude m b( Lg )=4.53 for the 25 May 2009 North Korean nuclear explosion. Based upon 15 first arrivals from the two North Korea nuclear explosions, the regional Pn velocity in the northeast China–North Korea region is calculated to be 8.0 km/s. This result, along with the regional geological structures, suggests that the North Korean test site (NKTS) is located at a relatively stable continental region. We thus use a modified fully coupled magnitude–yield relation to estimate the explosion yield, and the result shows that the yield of the 25 May 2009 North Korean nuclear test is approximately 2.35 kt under the minimum burial depth assumption. Online Material: Epicentral parameters, computed m b( Lg ), and corrected m b( Lg ) for 82 events used in the study.

We investigate the regional seismic signature of the 9 October 2006 North Korean nuclear test. Broadband regional data for the nuclear test and a group of earthquakes close to the test site were obtained between December 2000 and No- vember 2006. Epicentral distances from the stations to the test site are between 371 and 1153 km. We first use these regional events to calibrate the Lg-wave magnitude in the network. Then the network is used to calculate mbLg �� 3:93 for the North Ko- rean nuclear explosion. Using a modified fully coupled magnitude-yield relation, the yield of the North Korean nuclear test is estimated to be 0.48 kt. Because of large uncertainties in the source depth, the estimate is preliminary. The P=S-type spectral ratios Pg=Lg, Pn=Lg, and Pn=Sn are calculated for the nuclear explosion and a group of earthquakes close to the test site. At frequencies above 2 Hz, the network-averaged P=S spectral ratios clearly separate the 9 October 2006 explosion from the regional earthquakes. Our result indicates that a single-blast explosion in the North Korea re- gion shows different seismic characteristics from an earthquake. Any well-coupled single-blast explosion detonated in this region with yield similar to that for the North Korean nuclear test has a large probability of being identified by a regional seismic network such as the one adopted in this study.

The widely distributed Cenozoic sediments in the Bohai Bay Basin give rise to noticeable modification of broadband teleseismic P waveforms. At one station in the west Bohai Bay Basin, the observed amplitude of tangential P-receiver func- tions is significantly above the noise level, and sedimentary reverberations (e.g., the P-type wave PpPp) remain one of the most prominent features in both the radial and tangential components. To investigate the lateral heterogeneity structure under this site, a 3D raytracing technique is used to compute the teleseismic P-wave response, and a fast simulated annealing algorithm is applied to the simultaneous inversion of radial receiver functions for different backazimuths. An upper crustal structure con- sisting of shallow dipping sedimentary layers with low seismic velocities and large Poisson's ratios is proposed to interpret the observed seismic data. The west-dipping interfaces we obtained are consistent with the north-northeast-south-southwest sur- face geology in North China, and Tertiary extensional fault structures may be re- sponsible for the formation of dipping sedimentary layers.

Wogonoside, a bioactive flavonoid extracted from the root of Scutellaria baicalensis Georgi, has been reported to have anti-inflammatory and antioxidant effects. In this study, we examined the protective effects of wogonoside against lipopolysaccharide (LPS) and D-galactosamine (D-GalN)-induced liver injury in mice. Mice were given an intraperitoneal injection of wogonoside 1h before LPS and d-GalN treatment. The results showed that wogonoside inhibited the production of serum Alanine transaminase (ALT), Aspartate aminotransferase (AST), IL-1β, TNF-α, and hepatic malondialdehyde (MDA) content induced by LPS/GalN. In addition, wogonoside promoted the expression of Nrf2, NQO-1, GCLC, and HO-1. Wogonoside inhibited the expression of hepatic NLRP3, ASC, caspase-1, and IL-1β induced by LPS/GalN. In conclusion, these results suggest that wogonoside protects against LPS/GalN-induced acute liver injury by activating Nrf2 and inhibiting NLRP3 inflammasome activation.

A sequential waveform method is developed to simulate the seismic response of basin-edge structure excited by a plane incident P-wave. The full procedure involves: (a) a previous parameterization of the investigated model using the seismic wave velocities and depths of the sedimentary stratifications; (b) an input motion determined from the records at stations installed on hard rock; (c) forward computation of the P-SV elastic wave field by means of a two-dimensional finite difference (FD) method; (d) the optimization of the model vector using simulated annealing technique and comparing the simulated seismic response of the tested structure with the observed wave field; (e) the correction of the initial model by trial-and-error by testing the differences between synthetics and observed data, and (f) the final solution obtained by iteration using the conjugate gradient algorithm. The search of an optimal basin-edge model has been parallel processed by varying the shapes and velocities of strata on the basis of the fitting of relative timing, amplitude and phase between the output and the observed data. The input motion and sensitivity have been checked and the validity of the method has been demonstrated by numeric analysis. Using the teleseismic records generated by 7 earthquakes recorded at 26 broadband seismic stations, we have studied the seismic velocity structure of the southern edge of the Jiyang depression located in the Bohai Bay basin, northern China. Two cross sections show an agreement between the velocity results and the geological sections available in the region. In addition, we obtain evidence of three hidden faults under the sections and features that suggest major extensions at the Paleogene.

The predicted total yield of the Indian nuclear tests at Pokhran on May 11, 1998 (POK2) ranges from 12 to 60kt according to the literature. A factor of about five in the uncertainties of yield estimation motivated this study. Based on the broadband seismic body wave data from the Global Seismic Network, we inverted for the effective source model parameters and estimated the seismic yield of event POK2. We found that the empirical equation between the relative static strength and yield in Nevada test site (NTS) obtained by Lay[1] is appropriate for estimating the Indian nuclear test. Our result of 36kt for event POK2 supports the point of view that the yield of POK2 is significantly less than 60kt.

The source rupture process of the July 11, 2004, Tibet (Mw 6.2) earthquake is investigated by the finite fault model using far field broadband body wave records. The results show that it's a shallow, predominantly dip-slipping, normal-fault earthquake, and the hypocentral depth is about 12.5km. The fault plane has a strike of 152° and a dip of 44°, and the average slip angle is –117°. The rupture nucleates near the hypocenter, then propagates to the two ends of the fault with an average velocity of 2.8km/s, and the slip reaches to its maximum value of 43cm at about 5km northeast of the epicenter. The main principal tension axis of the fault plane solution shows roughly EW extension, which is controlled by the local rift belt in NNW-SSE or nearly NS direction, and the thrust motion of the India plate towards north is the main mechanical reason of this earthquake.