Spatial segmentation characteristic of focal mechanism of aftershock sequence of Wenchuan Earthquake

Moment tensor solutions of 88 earthquakes were determined by using the broadband waveform data recorded in six stations within 450 km around the Wenchuan Earthquake sequence by means of the time domain moment tensor inversion method. It was found that the type of the focal mechanism solution is characteristic of obvious spatial segmentation. There are six segments along the main rupture zone from southwest to northeast, where initially the focal mechanism is of main thrust type, finally of main right-lateral strike-slip type and between these two areas there is a transition zone characterized in multiple types of focal mechanisms appearing in turn. Earthquakes of left-lateral strike-slip type perpendicular to the main rupture zone occurred near Xiaoyudong Town. The stress field of each segment is inversed by means of the FMSI program, and it was found that, along the main rupture zone from southwest to northeast, the direction of the maximum principal stress is gradually changing from near EW to NW-SE, and finally changing back to near EW.     

Evidence of crustal ＇channel flow＇ in the eastern margin of Tibetan Plateau from MT measurements

Magnetotelluric （MT） survey has been carried out in the eastern margin of the Tibetan Plateau and its neighboring Shimian-Leshan area, Sichuan Province. Analysis of this MT data reveals that the electric structure of the Tibetan Plateau differ much from that of the Sichuan block. In general, the electric resistivity of crust beneath the Sichuan block in the east is larger than that of the eastern margin of the Tibetan Plateau in the west. The crust of the plateau is divided into upper, middle, and lower layers. The middle crust is a low resistivity layer with minimum down to 3-10Ωm about 10-15 km thick. It presumably contains partial melt and/or salt-bearing fluids with low viscosity, prone to deform and flow, producing a ＂channel flow＂ under the southeastward squeeze of the eastern Tibetan Plateau. This low-resistivity layer makes the upper crust decoupled mechanically from the lower crust. In the brittle upper crust, faults are dominated by left-lateral strike-slip and thrust motions, leading to surface rising and shallow earthquakes. The low-resistivity layer also cut the Xianshuihe-Anninghe fault zone into two sections vertically. In this region, the thicknesses of upper, middle, and lower crust vary laterally, producing a transitional zone in the eastern margin of the Tibetan Plateau characterized by thicker crust and higher elevation in the west and thinner crust and lower elevation in the east.     

The M S7.1 Yushu earthquake surface rupture and large historical earthquakes on the Garzê-Yushu Fault

As revealed by field investigations, the co-seismic surface rupture zone of the 2010 M_S7.1 Yushu earthquake, Qinghai is a char-acteristic sinistral strike-slip feature consisting of three distinct sinistral primary ruptures, with an overall strike of 310°–320° and a total length of 31 km. In addition, an approximately 2-km-long en-echelon tensile fissure zone was found east of Longbao Town; if this site is taken as the north end of the rupture zone, then the rupture had a total length of ~51 km. The surface rupture zone is composed of a series of fissures arranged in an en-echelon or alternating relationship between compressive bulges and tensile fissures, with a measured maximum horizontal displacement of 1.8 m. The surface rupture zone extends along the mapped Garzê-Yushu Fault, which implicates it as the seismogenic fault for this earthquake. Historically, a few earthquakes with a magnitude of about 7 have occurred along the fault, and additionally traces of paleoearthquakes are evident that characterize the short-period recurrence interval of large earthquakes here. Similar to the seismogenic process of the 2008 Wenchuan earthquake, the Yushu earthquake is also due to the stress accumulation and release on the block boundaries resulting from the eastward expansion of Qinghai-Tibet Plateau. However, in contrast with the Wenchuan earthquake, the Yushu earthquake had a sinistral strike-slip mechanism resulting from the uneven eastward extrusion of the Baryan Har and Sichuan-Yunnan fault blocks.     

联合slipBERI与D-InSAR技术的青海省玛多县地震形变场提取与模拟

针对2021年5月22日青海玛多县Ms7.4地震震区形变信息、形变特征以及滑动断裂特性的提取与模拟等问题,获取了玛多县地震区的Sentinel-1A影像,采用双轨差分干涉法,并优化各项参数,提取出同震形变场,利用slipBERI(slip from Bayesian Regularized Inversion)方法对断层的几何参数及形变场进行反演和模拟。结果表明：玛多地震同震形变场的形状近似于一个椭圆,断层整体呈西北-东南走向,其上部为沉降区,下部为隆升区,最大LOS(line of sight,视线向)形变分别为0.65m和0.81m。地震形变场的运动主要以东西方向的水平运动为主,并伴有明显的左旋走滑,断层上下方相对视线向运动可达1.50m,表明此次地震的地表破裂有明显的错位移动。通过分析形变信息和地表破裂特征,可以判断该破裂带位于巴颜喀拉块体,为昆仑山口-江口断裂,反演结果与观测结果相符,这表明观测结果较可靠。     

Rupture process of the Wenchuan <Emphasis Type="Italic">M</Emphasis>8.0 earthquake of Sichuan China: the segmentation feature

Moment tensor solution, rupture process and rupture characteristics of the great Wenchuan M8.0 earthquake are studied by using 39 long-period P and SH waveforms with evenly azimuth coverage of stations. Our results reveal that the Wenchuan M8.0 event consisted of 5 sub-events of Mw≥7.3 occurring succesively in time and space. Rupture started with a Mw7.3 introductory strike-slip faulting in the first 12 s, then within 12?40 s, two sub-events with Mw7.6 and Mw7.4 occurred within 80 km northeast from the init...     

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

Seismicity and slip rates along the Lijiang-Ninglang fault zone between 1999 and 2006 were investigated with the waveform data recorded by the Yunnan digital Seismic Network. The relocated seismicity by the double difference method clearly exhibits different features between the northern and southern segments. More than 76% earthquakes occurred in the southern segment of the fault near the Lijiang area. The relocated seismicity appears to reflect the crustal velocity structure of the study area. Using cross-correlation analysis, we identified a total of 92 doublets and 70 multiplets that show high waveform similarity. Most of these sequences are aperiodic with recurrence intervals varying from a few minutes to hundreds of days. Using two sequences that occurred regularly over the study period, we obtained a fault slip rate of approximately 5 mm/a at ∼23 km, in good agreement with geologic and surface GPS measurement. Supported by National Basic Research Program of China (Grant No. 2004CB418405) and National Natural Science Foundation of China (Grant No. 40174014)     

Influence of O2/Ar ratio on the properties of transparent conductive niobium-doped ZnO films

Niobium-doped ZnO transparent conductive films are deposited on glass substrates by radio frequency sputtering at 300℃. The influence of O2/Ar ratio on the structural, electrical and optical properties of the as-deposited films is investigated by X-ray diffraction, Hall measurement and optical transmission spectroscopy. The lowest resistivity of 4.0×10^-4Ω· cm is obtained from the film deposited at the O2/Ar ratio of 1/12. The average optical transmittance of the films is over 90%.     

Affected zone generated around the erosion pit on carbon steel surface at the incipient stage of vibration cavitation

The characteristics of erosion pits on a carbon steel surface were investigated at the incipient stage of cavitation erosion. After a 5-minute experiment performed in an ultrasonic vibration system, needle-like erosion pits appeared on the polished steel surface, and a specially affected zone was formed around the pit. The shape of the pit and the plastic deformation of the affected zone indicate that the me-chanical impaction on the surface is the main reason for the cavitation damage. On the other hand, the iridescent color, the decreased surface hardness and the precipitated carbides on the affected zone prove that the affected zone has experienced a tempering process with the temperature higher than 300℃. The lack of oxygen in the affected zone also proves that it is not a chemical oxygen result. A special phenomenon that a carbon ring forms in the affected zone is explained as a result of the tor- oidal bubbles＇ heating effect at the final stage of the bubble collapse.     

Study of the ionospheric anomaly before the Wenchuan earthquake

The behavior of the ionosphere before the Wenchuan earthquake is analyzed with the global TEC and ionospheric foF2 observed at Xiamen. It can be found from TEC maps that in the afternoon (16―18LT) on May 9, 2008, 3 days before the earthquake, there is an enhancement of TEC with an amplitude of 10―15 TECU appearing in the east-south direction of Wenchuan, and another enhancement appears at the conjugate region of the Southern Hemisphere with an amplitude of 10 TECU, but no obvious in-crement or decrement can be seen in other regions on global scale. It can also be found that on May 6 (6 days before the great earthquake), there is a decrement of TEC with small amplitude of 4TECU and larger area with 80° along the longitude in southern China, and there is no synchronous decrement observed at the conjugate region of the Southern Hemisphere. There are also many anomalies ob-served by ionosondes across China. The result shows that foF2 and TEC abnormally increased, which is different from pervious results that ionospheric parameters decreased prior to earthquakes. Pre-liminary results suggest that the enhancement on May 9 maybe has a close relationship with the pos-sible enhancement of ionospheric electric fields, and it may be an ionospheric precursor of earth-quakes. Whereas the decrement on May 6 may be attributed to the geomagnetic disturbance appearing on May 5.     

Synthesis and characterization of BiFeO3 nanotube arrays and Y-junction BiFeO3 nanotubes

Multiferroic BiFeO₃ (BFO) nanotube arrays (∼100 nm in diameter and ∼50 μm in length) were synthesized by the sol-gel method utilizing the anodic aluminum oxide (AAO) membrane technique. The microstructure and chemical components of the BFO nanotubes were investigated using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectrometer (XPS). The BFO nanotubes exhibited polycrystalline microstructures. The novel Y-junction BFO nanotubes were simultaneously fabricated. Supported by the National Natural Science Foundation of China (Grant No. 90306010), Program for New Century Excellent Talents in University (Grant No. NCET-04-0653) and National Basic Research Program of China (Grant No. 2007CB616911)     

SAR差分干涉测量技术在地震区域形变测量中的应用研究

合成孔径雷达(SAR)差分干涉测量是一种最新的大地形变测量遥感技术方法.利用欧洲空间局1996年4月15日获取的地球资源卫星ERS-1数据和4月16日获取的ERS-2数据,以及1997年12月2日获取的ERS-2数据,应用差分干涉测量技术对发生于1997年11月8日的西藏玛尼地震进行了提取区域形变场的应用研究.从得到的变化检测条纹图中可识别出地表破裂带,并可定量推算震中周围和两条断裂带附近的变形情况.分析结果表明:断裂为左行平移性质,断裂带南侧水平错动的最大变形量至少超过2.8 m,北侧水平错动的最大变形量至少超过1.75 m.差分干涉测量分析结果与地面调查及已有的相关研究资料符合得很好.     

^40Ar／^39Ar geochronological constraints on syn-orogenic strike-slip movement of Tan-Lu fault zone

Two phases of sinistral strike-slip ductile shear belts occur on the eastern margin of the Dabie orogenic belt. A muscovite ~(40)Ar/~(39)Ar plateau age of 128 Ma was obtained from mylonite in the later ductile shear zone. Three muscovite samples separated from mylonites of 3 localities in the earlier ductile shear belts yield ~(40)Ar/~(39)Ar plateau ages of 192.5±0.7 Ma, 189.7±0.6 Ma and 188.7±0.7 Ma, respectively. They are interpreted as cooling ages of the earlier sinistral strike-slip deformation. It is suggested that left-lateral displacement of the Tan-Lu fault zone started in a late stage of the collision orogeny in the Dabie-Sulu orogenic belt between the North and South China plates. Therefore, the earlier Tan-Lu fault zone was syn-orogenic strike-slip tectonics. The fault zone was used again for sinistral displacement during tectonic activities of peri-Pacific regime in Early Cretaceous. It is proposed that the fault zone occurred as a transform fault during the orogenic process.     

Rupture of the 2004 Sumatra-Andaman earthquake inferred from direct P-wave imaging

The Sumatra-Andaman earthquake on December 26, 2004 is the first well recorded gigantic earthquake (moment magnitude MW 9.3) by modern broadband seismic and Global Positioning System networks. The rich seismic and geodetic recordings have documented unprecedented details about the earthquake rupture, coseismic and postseismic deformations. This is a report of detailed images of the rupture process using the first-arriving compressional waves recorded by the China National Digital Seismic Network (CNDSN). An improved imaging condition was employed to account for the sparse distribution of the CNDSN stations. The resulting images are consistent with the major rupture features reported by previous seismic and geodetic studies. It is found that the earthquake rupture initiated at offshore of northwestern Sumatra and propagated in the north northwest direction at a speed of 2.7 ± 0.2 km/s. The rupture continued for at least 420 s and extended about 1200-1300 km along the Andaman trough with two bursts of seismic energy.     

A four-state memory cell based on magnetoelectric composite

A four-state memory can store four states in each memory cell. We designed a four-state memory cell using Co/PZT magnetoelectric composite and observed a broad magnetoelectric hysteretic output loop on applying magnetic field. Based on magnetoelectric hysteresis, we developed a read method by applying a bias magnetic field on the memory cell. Results gave clearly four-state signals of 15.8, -4.4, 5.5 and -11.3μV, which demonstrated the feasibility of our design.     

Coexistence of normal, super-, and hyper-deformation in nuclei: A study with angular momentum projection method

Angular-momentum-projected energy surface calculations for A ≈ 110 nuclei indicate three distinct energy minima occurring at different angular-momenta. These correspond to normal, super-, and hy- per-deformed shapes coexisting in one nucleus. 110Pd is studied in detail, with a quantitative prediction on super- and hyper-deformed spectra by the Projected Shell Model calculation. It is found that several other neighboring nuclei in the A-110 mass region, with the neutron number around 64, also exhibit clear s...     

川西石亭江地区遥感地质解译及构造解析

利用遥感地质解译以及土壤地球化学测量和地气测量,发现沿四川绵竹市和什邡市之间的石亭江发育走滑断裂.它们走向北西,雁行斜列,左行走滑.在两条主要左行走滑断裂的右侧叠覆区,两条主断裂第四纪的左行走滑运动产生一个胚胎期的菱形断陷.石亭江菱形断陷中可能形成了与断裂有关的地热系统,而浅层天然气可能沿断裂泄漏了.     

Induction of corneal epithelial prosenitors from bone-marrow mesenchymal stem cells of rhesus monkeys in vitro

Bioengineered corneas are substitutes for human donor tissue that are designed to treat severe disease affecting ocular surfaces. However, a shortage of candidate seed cells for bioengineering corneas is still a problem. Bone-marrow mesenchymal stem cells （MSCs） are capable of multilineage differentiation. Therefore, we determined whether MSCs differentiate into corneal epithelial cells （ECs）. We applied three exoteric-microenvironmental systems to induce MSCs to become ECs. Induced MSC were identified by means of morphologic examination, immunocytochemical analysis, and flow cytometry. MSCs grown in one microenvironment had characteristics similar to those of corneal epithelial progenitors. Induced MSCs expressed markers for EC, including integrin 61, Cx43, Pax6, and P63. MSCs were successfully induced to become corneal epithelial progenitors. Therefore, the use of MSCs may hold substantial promise for reconstructing the ocular surface after corneal injury.[第一段]     

A novel heteroseneous reaction for generating gaseous nitrous acid

The short-lived reactive specimen nitrous acid HONO was generated in the gas phase by the heterogeneous reaction of gaseous HCl with AgNO2 which can generate higher concentration of HONO than other methods. We investigated the process from generation to dissociation in the gas phase under different controlled temperatures, and discussed the ionization and reaction on the solid surface by combination of the photoelectron spectroscopy and photoionization mass spectroscopy （PES-PIMS） and in situ diffuse reflectance infrared Fourier transform spectroscopy （DRIFTS）.     

An exceptionally well-preserved fossil Kalligrammatid from the Jehol Biota

A new species of Neuroptera, Sophogramma lii sp. nov. is described and illustrated in this paper. This new species is assigned to Sophogramma Ren of Kalligrammatidae, mainly based on its humeral recurrent veins, the basal cell present between posterior branch of media at base of wing, etc. The new species is distinguished from all other Sophogramma species on the difference of wing venation. This exceptionally well-preserved specimen is recovered from the Yixian Formation, Huangbanjigou, located near Beipiao City, in western Liaoning Province. The genus diagnosis has been emended based on new characters shown in this new species. Based on a summary of localities, distribution and geological ages of all genera and species of the Kalligrammatidae, we suggest that Kalligrammatids might have originated in Eastern Asia, especially in China. Function of the wing pigmentation is discussed briefly. Supported by National Natural Science Foundation of China (Grant Nos. 30430100 and 40872022), Beijing Natural Science Foundation Program (Grant No. 5082002), Scientific Research Key Program (Grant No. KZ200910028005) and PHR Project of of Beijing Municipal Commission of Education, Science-Technology Basic Condition Platform from the Ministry of Science and Technology of the People’s Republic of China (Grant No. 2005DKA21402)     

Ultrahigh resolution optical coherence tomography with femtosecond Ti:sapphire laser and photonic crystal fiber

Optical coherence tomography （OCT） with ultrahigh axial resolution was achieved by the super-continuum generated by coupling femtosecond pulses from a commercial Ti：sapphire laser into an air-silica microstructure fiber. The visible spectrum of the super-continuum from 450 to 700 nm centered at 540 nm can be generated. A free-space axial OCT resolution of 0.64 pm was achieved. The sensitivity of OCT system was 108 dB with incident light power 3 mW at sample, only 7dB below the theoretical limit. Subcellular OCT imaging was also demonstrated, showing great potential for biomedical application.