Focal Mechanism Solutions of the 2008 Wenchuan earthquake sequence from P-wave polarities and SH/P amplitude ratios: new results and implications

The 2008 Wenchuan earthquake, a major intraplate earthquake with Mw 7.9, occurred on the slowly deforming Longmenshan fault. To better understand the causes of this devastating earthquake, we need knowledge of the regional stress field and the underlying geodynamic processes. Here, we determine focal mechanism solutions (FMSs) of the 2008 Wenchuan earthquake sequence (WES) using both P-wave first-motion polarity data and SH/P amplitude ratio (AR) data. As P-wave polarities are more reliable information, they are given priority over SH/P AR, the latter of which are used only when the former has loose constraint on the FMSs. We collect data from three categories: (1) permanent stations deployed by the China Earthquake Administration (CEA); (2) the Western Sichuan Passive Seismic Array (WSPSA) deployed by Institute of Geology, CEA; (3) global stations from Incorporated Research Institutions for Seismology. Finally, 129 events with magnitude over Ms 4.0 in the 2008 WES are identified to have well-constrained FMSs. Among them, 83 are well constrained by P-wave polarities only as shown by Cai et al. (Earthq Sci 24(1):115–125, 2011), and the rest of which are newly constrained by incorporating SH/P AR. Based on the spatial distribution and FMSs of the WES, we draw following conclusions: (1) the principle compressional directions of most FMSs of the WES are subhorizontal, generally in agreement with the conclusion given by Cai et al. (2011) but with a few modifications that the compressional directions are WNW–ESE around Wenchuan and ENE–WSW around Qingchuan, respectively. The subhorizontal compressional direction along the Longmenshan fault from SW to NE seems to have a left-lateral rotation, which agrees well with regional stress field inverted by former researchers (e.g., Xu et al., Acta Seismol Sin 30(5), 1987; Acta Geophys Sin 32(6), 1989; Cui et al., Seismol Geol 27(2):234–242, 2005); (2) the FMSs of the events not only reflected the regional stress state of the Longmenshan region, but also were obviously controlled by the faults to some extent, which was pointed out by Cai et al. (2011) and Yi et al. (Chin J Geophys 55(4):1213–1227, 2012); (3) while the 2008 Wenchuan earthquake and some of its strong aftershocks released most of the elastic energy accumulated on the Longmenshan fault, some other aftershocks seem to occur just for releasing the elastic energy promptly created by the 2008 Wenchuan earthquake and some of its strong aftershocks. (4) Our results further suggest that the Longmenshan fault from Wenchuan to Beichuan was nearly fully destroyed by the 2008 Wenchuan earthquake and accordingly propose that there is less probability for great earthquakes in the middle part of the Longmenshan fault in the near future, although there might be a barrier to the southwest of Wenchuan and it is needed to pay some attention on it in the near future.Wenchuan Fault Scientific Drilling Progra

Face-to-face intercrossed ZnO nanorod arrays with extensive NR-NR homojunctions for a highly sensitive and self-powered ultraviolet photodetector

Abstract(#br)A self-powering ultraviolet photodetector (UVPD) that effectively utilizes UV energy in an easy-to-implement way is an attractive alternative for the UV optical sensing and communication. Here we report a novel self-powered UVPD based on a face-to-face hybrid ZnO nanorod arrays (ZNRAs) nanostructure. Large-area free-standing ZNRAs have been grown on indium tin oxide (ITO) conductive glass and Ti substrates through a hydrothermal method. Different geometric dimension of ZNRAs/ITO and ZNRAs/Ti structures were designed to pair hybrid each other for achieving the optimum photoelectric performance. Experimentally, it is found that the optimum UVPD based on face-to-face hybrid ITO/ l -ZNRAs/ l -ZNRAs/Ti structure exhibits an enhancement of ‘1+1>2’ in photoelectric conversion without applying any external DC voltage when compared with single-face ZNRAs-based UVPDs, and the optimum UVPD demonstrates a responsivity of 2.45 mA W −1 and on/off current ratio of 6.6 × 10 5 under a UV irradiation of 3.06 μW cm −2 as well as a high durability with a cyclic balance of no less than 93.5% in a 4250-s on/off irradiation. The generation of self-power and the high photoelectric performance of face-to-face hybrid ZNRAs-based UVPDs are associated to the Schottky junctions in ITO/ZnO interface as well as the extensive ZnO nanorod-nanorod homojunction

Strain hardening of as-extruded Mg-xZn (x = 1, 2, 3 and 4 wt%) alloys

The influence of Zn on the strain hardening of as-extruded Mg-xZn (x = 1, 2, 3 and 4 wt%) magnesium alloys was investigated using uniaxial tensile tests at 10 s at room temperature. The strain hardening rate, the strain hardening exponent and the hardening capacity were obtained from true plastic stress-strain curves. There were almost no second phases in the as-extruded Mg-Zn magnesium alloys. Average grain sizes of the four as-extruded alloys were about 17.8 μm. With increasing Zn content from 1 to 4 wt%, the strain hardening rate increased from 2850 MPa to 6810 MPa at (σ-σ) = 60 MPa, the strain hardening exponent n increased from 0.160 to 0.203, and the hardening capacity, Hc increased from 1.17 to 2.34. The difference in strain hardening response of these Mg-Zn alloys might be mainly caused by weaker basal texture and more solute atoms in the α-Mg matrix with higher Zn content

Induced systemic resistance against Pythium aphanidermatum by plant growth-promoting rhizobacteria on cucumber (Cucumis sativus L.)

Cucumber root rot caused by Pythium aphanidermatum can be suppressed by introduced plant growth-promoting rhizobacteria (PGPR). Preliminary experiments clarified that this root disease could be suppressed by strains of Pseudomonas aureofaciens, P. corrugata, and P. fluorescens. To determine whether the mechanism was a systemic resistance induced by PGPR, a split root technique was employed on greenhouse cucumbers grown in soilless substrates. On the split roots, bacteria which were introduced into one side of the root were completely separated from pathogen challenged-inoculated roots-on the other side of the roots. Results from the series of experiments conducted with this design demonstrated that (i) the resistance against root rot induced by PGPR was systemic, (ii) germination of P. aphanidermatum zoospores was reduced in extracts from bacterized roots compared to non-treated control, and (iii) spread of Pythium mycelia was delayed and zoospore germination was inhibited on the distant induced root, compared to the non-bacterized control. Furthermore, enzyme analysis indicated that phenylalanine ammonia lyase, peroxidase and polyphenoloxidase increased on cucumber roots two days after they were bacterized with Pseudomonas strains 13 or 63--28. When the bacterized roots were challenged with P. aphanidermatum, these plant defense enzymes increased as the symptoms appeared, but this accumulation of enzymes was not any higher on roots induced with each of the Pseudomonas strains compared to the Pythium inoculated control. This enzyme stimulation was also systemically induced by PGPR or P. aphanidermatum on cucumber roots. The patterns of iso-peroxidase induced with the PGPR and P. aphanidermatum treatments were different. High levels of salicylic acid (SA) accumulated in bacteria-induced roots, as well as in pathogen-infected roots, which suggests that SA may be associated with cucumber resistance response. But exogenous application of SA did not induce any system

Fluid Inclusion Constrained Multiple Petroleum Chargings in the Lithologic Reservoirs of the Late Eocene Shahejie Formation in the Minfeng Sag, Bohai Bay Basin, East China

The fluid inclusion technique was utilized to reveal the petroleum charging events in the lithologic reservoirs embraced in the Late Eocene Shahejie Formation of the Minfeng sag, Bohai Bay Basin, East China. Petrography, fluorescence microspectrometry, and microthermometry were systematically carried out on 15 double-polished thin sections handled from reservoir core samples of the third Member of the Shahejie Formation. The results show that three generations of petroleum inclusions with fluorescence colors of yellow, yellowish green and bright blue were entrapped along the healed fractures in detrital quartz grains of these samples. The fluorescence features of petroleum inclusions illustrate that inclusion oils have different maturities and were products of source rocks at different stages. In addition, the trapping time of petroleum inclusions was determined by combining the homogenization temperatures of their coeval aqueous inclusions with thermal-burial histories. By integrating the petrographic occurrence, characteristics of petroleum inclusions, and the maturity and the trapping time of the studied inclusion oils, it is jointly constrained that the lithologic reservoirs of the Late Eocene Shahejie Formation in the Minfeng sag underwent three petroleum chargings, which occurred during 37.8~25 Ma, 11.7~3.5 Ma and 1.4~0.1 Ma, respectively. The petroleum from each charging period migrated from the center of the sag to the edge, and the lower the maturity of the migrating petroleum, the longer the migration duration

Fluid Inclusion Constrained Multiple Petroleum Chargings in the Lithologic Reservoirs of the Late Eocene Shahejie Formation in the Minfeng Sag, Bohai Bay Basin, East China

The fluid inclusion technique was utilized to reveal the petroleum charging events in the lithologic reservoirs embraced in the Late Eocene Shahejie Formation of the Minfeng sag, Bohai Bay Basin, East China. Petrography, fluorescence microspectrometry, and microthermometry were systematically carried out on 15 double-polished thin sections handled from reservoir core samples of the third Member of the Shahejie Formation. The results show that three generations of petroleum inclusions with fluorescence colors of yellow, yellowish green and bright blue were entrapped along the healed fractures in detrital quartz grains of these samples. The fluorescence features of petroleum inclusions illustrate that inclusion oils have different maturities and were products of source rocks at different stages. In addition, the trapping time of petroleum inclusions was determined by combining the homogenization temperatures of their coeval aqueous inclusions with thermal-burial histories. By integrating the petrographic occurrence, characteristics of petroleum inclusions, and the maturity and the trapping time of the studied inclusion oils, it is jointly constrained that the lithologic reservoirs of the Late Eocene Shahejie Formation in the Minfeng sag underwent three petroleum chargings, which occurred during 37.8~25 Ma, 11.7~3.5 Ma and 1.4~0.1 Ma, respectively. The petroleum from each charging period migrated from the center of the sag to the edge, and the lower the maturity of the migrating petroleum, the longer the migration duration

A Method of Segmentation and Organization of Multi-section Video Data

AbstractThe purpose of this invention is to provide a method for the segmentation organization of multi-section videos based on GPS in the GIS (Geographical Information System). The topological relationship is gained by integrating the geographical information with the video information, extracting the information of nodes in the road network and every section. By segmenting and organizing the videos according to the topological relationship to obtain rapid retrieval and positioning between the geographical coordinates and the video frames so as to provide roaming based on the actual scene for users. This invention is mainly suitable for the application of GIS based on videos in the traffic management. With this method, GPS positioning information and real-time collection & video playback of the road video images can be realized, including searching & positioning and synchrocontrol with E-maps of videos

The seed plant flora of the Mount Jinggangshan region, southeastern China.

The Mount Jinggangshan region is located between Jiangxi and Hunan provinces in southeastern China in the central section of the Luoxiao Mountains. A detailed investigation of Mount Jinggangshan region shows that the seed plant flora comprises 2,958 species in 1,003 genera and 210 families (Engler's system adjusted according to Zhengyi Wu's concept). Among them, 23 species of gymnospermae belong to 17 genera and 9 families, and 2,935 species of angiosperms are in 986 genera and 201 families. Moreover, they can also be sorted into woody plants (350 genera and 1,295 species) and herbaceous plants (653 genera and 1,663 species). The dominant families are mainly Fagaceae, Lauraceae, Theaceae, Hamamelidaceae, Magnoliaceae, Ericaceae, Styracaceae, Aquifoliaceae, Elaeocarpaceae, Aceraceae, Rosaceae, Corylaceae, Daphniphyllaceae, Symplocaceae, Euphorbiaceae, Pinaceae, Taxodiaceae, Cupressaceae and Taxaceae. Ancient and relic taxa include Ginkgo biloba, Fokieniahodginsii, Amentotaxusargotaenia, Disanthuscercidifolia subsp. longipes, Hamamelismollis, Manglietiafordiana, Magnoliaofficinalis, Tsoongiodendronodorum, Fortuneariasinensis, Cyclocaryapaliurus, Eucommiaulmoides, Sargentodoxacuneata, Bretschneiderasinensis, Camptothecaacuminata, Tapisciasinensis, etc. The flora of Mount Jinggangshan region includes 79 cosmopolitan genera and 924 non-cosmopolitan genera, which are 7.88% and 92.12% of all genera. The latter includes 452 tropical genera (48.92%) and 472 temperate genera (51.08%). The temperate elements include 44 genera endemic to China, accounting for 4.76% of all genera. Among 1,003 genera, 465 have only a single species and 401 are oligotypic genera (with 2-5 species). These genera account for 86.34% of all genera. The floristic analysis indicates that the flora of Mount Jinggangshan region is closely related to the flora of Mount Wuyishan region in southeastern China. The flora of Mount Jinggangshan region also contains many elements of central and southern China. Mount Jinggangshan region is an important north-south floristic passageway and is also a boundary between the floras of eastern, central and south China

Fine-grained sublacustrine fan deposits and their significance in shale oil reservoirs in the Lucaogou Formation in the Jimsar Sag, Junggar Basin

Objective The Jimsar Sag of the Junggar Basin is representative of successful shale oil exploration in China. However, the sedimentary facies in the Permian Lucaogou Formation hosting shale oil has long been disputed. Previous studies proposed two contradictory environments of shallow lakes and semideep to deep lakes in the interior lacustrine basin and identified sandstone interlays as deltaic distal sandbar deposition and beach and bar deposition. Methods The study combined core observations with analyses of sandstone granularity, logging facies, and reservoir properties to identify the development of sublacustrine fans in a semi-deep to deep lake background. Results Fine-grained turbidity currents played a significant role in the transportation and deposition of sediment in these fans. The lithofacies observed included lenticular-wave bedded muddy siltstone to siltstone (dominant type), parallel bedded siltstone, graded siltstone, and massive-graded bedded siltstone to fine-grained sandstone. The cumulative probability granularity curves exhibited smooth upper arches with a high suspension population, and the cross-spots on the C-M diagram were located in the grade suspension zone. The sublacustrine fans consisted of sedimentary microfacies of sheet-like lobes and gravity flow channel levees, showing fining- and coarsening-upwards successions, respectively. These fans contained numerous interlayers of siltstone and fine-grained sandstone, as well as terrigenous detrital particles that influenced the mineral content and enhanced shale oil reservoir properties by promoting the growth of solution pores. Conclusion The study concluded that sublacustrine fan deposits are thin-bedded and fine-grained, and they occur frequently. It also determined that desert reservoirs formed in the areas where sublacustrine fans were deposited, which has significant implications for shale oil exploration in the study area