Spatiotemporal characteristics of the energy radiation sources of the three great earthquakes near Sumatra Island in September 2007

Three strong earthquakes with magnitudes of Mw 8.4, Mw 7.9 and Mw 7.0 occurred in the sea west of Sumatra Island on September 12 and 13, 2007. We relocated the epicenters and focal depths of the three events by means of the reversal-time imaging technique using broadband digital seismic data from worldwide stations ranging from 30° to 90°, imaged the spatiotemporal variation of the energy radiation sources by means of the nonplane wave array technique using the broadband digital seismic data from a generalized array made up of 33 stations of the Capital Region Digital Seismograph Network （CRDSN）, and obtained the rupture duration times, extents and rupture velocities. Also, we discussed the correlations between the locations of the energy radiation sources of the three events.     

Slip zone and energetics of a large earthquake from the Taiwan Chelungpu-fault Drilling Project

Determining the seismic fracture energy during an earthquake and understanding the associated creation and development of a fault zone requires a combination of both seismological and geological field data. The actual thickness of the zone that slips during the rupture of a large earthquake is not known and is a key seismological parameter in understanding energy dissipation, rupture processes and seismic efficiency. The 1999 magnitude-7.7 earthquake in Chi-Chi, Taiwan, produced large slip (8 to 10 metres) at or near the surface, which is accessible to borehole drilling and provides a rare opportunity to sample a fault that had large slip in a recent earthquake. Here we present the retrieved cores from the Taiwan Chelungpu-fault Drilling Project and identify the main slip zone associated with the Chi-Chi earthquake. The surface fracture energy estimated from grain sizes in the gouge zone of the fault sample was directly compared to the seismic fracture energy determined from near-field seismic data. From the comparison, the contribution of gouge surface energy to the earthquake breakdown work is quantified to be 6 per cent.     

Focal mechanism analysis and parameter estimation of Zhangbei-Shangyi earthquake from differential SAR interferometry

On 10 January, 1998 an earthquake of Ms=6.2occurred in the Zhangbei-Shangyi region of North China.The surface seismic deformation was measured in the previous study using the 3 pass ERS-1/2 SAR differential interferometric technology (D-INSAR). In this note the focal mechanism of Zhangbei-Shangyi earthquake is estimated from the D-INSAR measurement of surface deformation based on a standard elastic dislocation model for seismic displacement. The inversion procedure is an iterative, linear least-squares algorithm. Through the relation between the focal parameters and displacement in the line of sight direction measured in the radar interferogram, the optimum focal parameter set is derived. The results show that the seismic fault of Zhangbei-Shangyi earthquake is a thrust fault dipping SW with a large right-lateral displacement component.The strike and dip are 95° and 30° respectively on a fault patch of 12 km long by 14 km wide. Its hypocenter is located at N40°58', E114°21', and 7.5 km in depth. The estimated slip vector is 0.728 m with a rake of 105.95°, the trend of slip is NW13.26°, and M0is 2.69×1018 N @ m.     

Fine mapping of the red plant gene R1 in upland cotton(Gossypium hirsutum)

Sub 16 is a substitution line with G. hirsutum cv. TM-1 genetic background except that the 16th chromosome (Chr. 16) is replaced by the corresponding homozygous chromosome of G. barbadense cv. 3-79, and T586 is a G. hirsutum multiple gene marker line with 8 dominant mutation genes. The R ₁ gene for anthocyanin pigmentation was tagged in Chr. 16 in T586. The objective of this research was to screen SSR markers tightly linked with R ₁ by using the F₂ segregating population containing 1259 plants derived from the cross of Sub 16 and T586 and the backbone genetic linkage map from G. hirsutum×G. barbadense BC₁ newly updated by our laboratory. Genetic analysis suggested that the segregation ratio of red plants in the F₂ population fit Mendelian 1:2:1 inheritance, confirming that the red plant trait was controlled by an incomplete dominance gene. Preliminary mapping of R ₁ was conducted using 237 randomLy selected F₂ individuals and JoinMap v3.0 software. Then, a fine map of R1 was constructed using the F₂ segregating population containing 1259 plants, and R ₁ was located between NAU4956 and NAU6752, with only 0.49 cM to the nearest maker loci (NAU6752). These results provided a foundation for map-based cloning of R ₁ and further development of cotton cultivars with red fibers by transgenic technology. Supported by National Natural Science Foundation of China (Grant No. 30730067) and Programme of Introducing Talents of Discipline to Universities (Grant No. B08025)     

Slip model for the 2011 M_w 9.0 Sendai （Japan） earthquake and its M_w 7.9 aftershock derived from GPS data

Using GPS-measured coseismic and post-seismic displacements for the 8 h following the M w 9.0 Sendai earthquake of March 11, 2011, coseismic and post-seismic fault slip models were developed based on a layered crustal model. The geodetic moment magnitude of the main shock was measured as approximately M w 8.98. The slip exhibits clear reverse characteristics, with a maximum near the hypocenter, and a magnitude of about 23.3 m. Some strike-slip behavior may occur on the two sides of the peak rupture zone. Almost 90% of the seismic moments released by the main shock occurred at depths less than 40 km. The energy released by the fault slip in the 8 h following the main shock is approximately equal to an earthquake of M w 8.13. With a maximum of ~1.5 m, the post-seismic slip was concentrated in the southwestern part of the coseismic rupture fault, which agrees well with the location and behavior of the M w 7.9 aftershock. This implies that the post-seismic deformation in the 8 h after the main shock was mainly induced by the M w 7.9 aftershock. In addition, a post-seismic slip of 0.2-0.4 m was observed at the down-dip extension of the coseismic rupture, which may have been caused by the effect of after-slip during this period.     

Complicated phenomena of the Beichuan-Yingxiu surface fracture zone during Wenchuan <Emphasis Type="Italic">M</Emphasis>s8.0 earthquake in Sichuan Province,China

After Wenchuan Ms8.0 earthquake, the surface fractures have been investigated in Beichuan City and Yingxiu Town. It was found that the Beichuan-Yingxiu earthquake fracture zone trends northeastward, dipping to northwest. The earthquake fracture zone is mainly characterized by thrust faulting with small amounts of strike-slip movement, and demonstrating various complexities for different areas. The phenomena related to dextral strike-slip displacement are found in Beichuan City and those related to left-lateral strike-slip movement in Yingxiu Town. The compressive shortening of the two surface fracture zones in Beichuan City is 2.8-3.9 m and the left-lateral strike-slip displacement of the surface fractures in Yingxiu Town is 0.52 m.     

Lushan M S7.0 earthquake: A special earthquake occurs on curved fault

Relocation result shows that the aftershocks of the Lushan M _S7.0 earthquake spatially distribute in a shape like “half bowl”, indicating that the rupture structure of the mainshock is a highly curved surface. Kinematic analysis reveals that a laterally varied dislocation pattern occurs on this curved fault even though a single relative horizontal movement controls slip on this fault. Reverse slip prevails on curved fault. However, significant normal slip is predicted near the edge of north flank. Moreover, the north flank features left-lateral slip while the south flank contrarily features right-lateral slip. The relative scope of aftershock distribution implies inadequate breaking of the curved fault during the mainshock, calling for the attention to potential earthquake risk on the neighboring portions of the coseismic rupture due to significant increase of the coseismic Coulomb stress. Coseismic stress modeling also reveals that it is unnecessary for the stress on ruptured part to be unloaded following the earthquakes on the curved fault. The coseismic stress loading on ruptured elements unveils the specialty of faulting for the Lushan earthquake and we conclude that this specialty is due to the highly curved fault geometry.     

Effects of ultraviolet radiation B （UV-B） on photosynthesis of natural phytoplankton assemblages in a marine bay in Southern China

Solar ultraviolet radiation B (UVB) is known to have inhibitive effects on phytoplankton photosynthesis. UVB light decreases rapidly with increasing depth in the water column and exerts different degrees of UVB inhibitive effects on phytoplankton photosynthesis. In this study, the objectives were to quantify effects of UVB on phytoplankton photosynthesis and quantum yield, and to examine UVB effects on phytoplankton photosynthesis when light varies. The insitu experiments were conducted in Da Ya Bay, which is a semienclosed area in the subtropical South China. The results showed a significant reduction of photosynthetic rates and quantum yield in the presence of UVB. Maximum photosynthetic rates (Pmax) and maximum quantum yield (Φmax) were 11%-22% and 17%-49% less under solar radiation with UVB than without UVB. A simplified model was developed to describe the UVB biologically effective fluence rate (E*inh) as an exponential decay function of depth. Light-shift experiments, in which water samples from the surface and at depth of 4 m were divided into several subsamples, and each subsamples were then incubated at different depths with and without UVB in the water column, showed that phytoplankton from the deeper water (4 m) had more inhibitive rates by UVB than that from the surface when exposed to the same light condition.     

Core-shell microstructure formed in the ternary Fe-Co-Cu peritectic alloy droplet

The metastable liquid phase separation occurs in the ternary Cu₅₀Fe_37.5Co_12.5 peritectic alloy droplets during free fall. The separated alloy melt rapidly solidifies and evolves core-shell microstructure composed of L₁(Cu) and L₂(Fe,Co) phases. Based on the determination of the phase transition temperature, the core-shell microstructure evolution, the interfacial energy, the temperature gradient and the Marangoni migration are analyzed. The interfacial energy of the separated liquid phase increases with the decrease of the temperature. The temperature gradient changes from large to small along the radius direction from inside to outside in the alloy droplet. The Marangoni force (F _M) acting on the micro-droplet of L₂(Fe,Co) phase increases with the increase of the size of the L₂(Fe,Co) phase, and decreases with the increase of undercooling. Driven by F _M, the micro-droplet of L₂(Fe,Co) phase migrates from outside to inside in the alloy droplet, collides and coagulates each other during migration, and then forms different types of core-shell microstructures. Supported by the National Natural Science Foundation of China (Grant Nos. 50121101, 50395105) and NPU Youth Scientific and Technological Innovation Foundation (Grant No. W016223)     

The Lushan M S7.0 earthquake and activity of the southern segment of the Longmenshan fault zone

Following the Lushan M _S7.0 earthquake on 20 April 2013, a topic of much concern is whether events of M _S7 or greater could occur again on the southern segment of the Longmenshan fault zone. In providing evidence to answer this question, this work analyzes the tectonic relationship between the Lushan event and the 2008 Wenchuan earthquake and the rupture history of the southern segment of the Longmenshan fault zone, through field investigations of active tectonics and paleoearthquake research, and our preliminary conclusions are as follows. The activity of the southern segment of the Longmenshan fault zone is much different to that of its central section, and the late Quaternary activity has propagated forward to the basin in the east. The seismogenic structure of the 2008 Wenchuan earthquake is the central-fore-range fault system, whereas that of the 2013 Lushan event is attributed to the fore-range-range-front fault system, rather than the central fault. The southern segment of the Longmenshan fault zone becomes wider towards the south with an increasing number of secondary faults, of which the individual faults exhibit much weaker surface activity. Therefore, this section is not as capable of generating a major earthquake as is the central segment. It is most likely that the 2013 earthquake fills the seismic gap around Lushan on the southern segment of the Longmenshan fault zone.     

C-H···Pd(II) interaction-driven homochiral M helix formation of neutral (R,R)-bis(pyrrol-2-ylmethyl- eneamino) cyclohexane palladium(II) complex

A chiral complex of (R,R)-Pd was prepared by reaction of optically pure (R,R)-bis(pyrrol-2-ylmethyl-eneamino) cyclohexane ligand with Pd(OAc)2·2H2O under the base condition at room temperature. The weak intermolecular C-H···Pd interaction was found to be responsible for the homochiral M helix for-mation of the neutral,chiral,mononuclear (R,R)-Pd in the crystal packing.     

The spatial distribution pattern of landslides triggered by the 20 April 2013 Lushan earthquake of China and its implication to identification of the seismogenic fault

After the 20 April 2013 Lushan MS6.6 earthquake occurred,investigation and identification of the seismogenic fault for this event have become a focused and debatable issue.This work prepared an initial landslide inventory map related to the Lushan earthquake based on field investigations and visual interpretation of high-resolution aerial photographs and provided evidence for solving the issue aforementioned.The analysis of three landslide-density profiles perpendicular to strike direction of the probable seismogenic fault shows that many landslides occurred on the footwall of the Shuangshi–Dachuan fault(SDF),without sudden change of landslide density near the fault.Very few landslides were detected near the Dayi fault(DF)and also no change of landslide density there.While obvious sudden change of landslide density appeared about 1–2 km from the northwest to the western Shangli fault(WSF),and the landslide density on the hanging wall of the fault is obviously higher than that of on the footwall.Therefore,we infer that the seismogenic fault for the Lushan earthquake is neither the SDF nor the DF,rather probably the WSF located between these two faults,which is an evident linear trace on the earth surface.Meanwhile,the coseismic slip did not propagate upward to the ground,implying the Lushan earthquake was spawned by a blind-thrust-fault beneath the WSF.     

The distribution characteristics of the flows in the near-Earth region： TC-1 observational results

TC-1 observational results clearly indicate that the velocity of the flows in the near-Earth region is dependent on the satellite location. The flow speed decreases while satellite moves close to the Earth. The plasma flow in the region close to the Earth tends to drift into the midnight region from the dawn and dusk region while the flow in the region away from the Earth shows an opposite drift. The observational results also show that the tailward flows are mainly located in the plasma sheet boundary while the earthward flow becomes dominant in the plasma sheet. It is found that both the strong tailward and earthward flows are distributed in the region around X= -11 Re, which coincides with the trigger region of the substorm onset. Hence, it may suggest that the flows are related with the trigger of the substorm onset. In addition, the BBFs coming from the mid-tail maily distributed in the region where X〈-9R E a n d ｜Z｜ 〈 3 R E that differs from the convection.     

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.     

Colluvial wedges associated with pre-historical reverse faulting paleoearthquakes

Colluvial wedges collapsed from fault scarp can also be used to study reverse faulting paleoearthquakes. Generating processes of reverse faulting colluvial wedges are much more complex than those associated with normal faulting earthquakes. Reverse faulting colluvial wedge is also in triangle shape, and dies away from the fault. Contact between the fault and the colluvial wedge may be a simple straight reverse fault or a combination of an erosive surface in the upper part and a reverse fault in the lower part. Contents and grain sizes increase near the fault and along the base of a colluvial wedge. Based on examples from the piedmont reverse fault and fold along the northern Tainshan, we studied characteristics of reverse faulting colluvial wedges, and discussed the generating processes of reverse faulting colluvial wedges. Reverse faulting generates an unstable scarp hanging in the air immediately after an earthquake. Fallen material deposits along the base of newly formed fault scarp. Erosive surface and surface of colluvial wedge form an antithetic scarp with an opposite direction to underlain reverse fault. If the later stage colluvium covers both the early stage colluvium and the erosive surface, the colluvial wedge will have a curved vertical edge with reverse fault in the lower part and erosive surface in the upper part. If the erosive surface is not covered by later stage colluvium, the colluvial wedge will only have a simple straight vertical edge, which is the reverse fault. A colluvial wedge represents a paleoearthquake event, but the height of the wedge is not equal to vertical offset of the paleoearthquake.     

Preliminary results pertaining to coseismic displacement and preseismic strain accumulation of the Lushan M S7.0 earthquake, as reflected by GPS surveying

This paper presents the coseismic displacement and preseismic deformation fields of the Lushan M _S7.0 earthquake that occurred on April 20, 2013. The results are based on GPS observations along the Longmenshan fault and within its vicinity. The coseismic displacement and preseismic GPS results indicate that in the strain release of this earthquake, the thrust rupture is dominant and the laevorotation movement is secondary. Furthermore, we infer that any possible the rupture does not reach the earth’s surface, and the seismogenic fault is most likely one fault to the east of the Guanxian-Anxian fault. Some detailed results are obtainable. (1) The southern segment of the Longmenshan fault is locked preceding the Lushan earthquake. After the Wenchuan earthquake, the strain accumulation rate in the southeast direction accelerates in the epicenter of the Lushan earthquake, and the angle between the principal compressional strain and the seismogenic fault indicates that a sinistral deformation background in the direction of the seismogenic fault precedes the Lushan earthquake. Therefore, it is evident that the Wenchuan M _S8.0 earthquake accelerated the pregnancy of the Lushan earthquake. (2) The coseismic displacements reflected by GPS data are mainly located in a region that is 230 km (NW direction) × 100 km (SW direction), and coseismic displacements larger than 10 mm lie predominantly in a 100-km region (NW direction). (3) On a large scale, the coseismic displacement shows thrust characteristics, but the associated values are remarkably small in the near field (within 70 km) of the earthquake fault. Meanwhile, the thrust movement in this 70-km region does not correspond with the attenuation characteristics of the strain release, indicating that the rupture of this earthquake does not reach the earth’s surface. (4) The laevorotation movements are remarkable in the 50-km region, which is located in the hanging wall that is close to the earthquake fault, and the corresponding values in this case correlate with the attenuation characteristics of the strain release.     

Deep structure beneath the southwestern section of the Longmenshan fault zone and seimogenetic context of the 4.20 Lushan M S7.0 earthquake

Magnetotelluric measurements were carried out along two profiles across the middle and southwestern sections of the Longmenshan fault zone (LMSf) from 2009 to 2011, after the 2008 Wenchuan M _W7.9 earthquake. The former profile crosses the Wenchuan event epicenter and the latter one crosses 2013 Lushan M _S7.0 event epicenter. The data were analyzed using advanced processing techniques, including phase tensor and two-dimensional inversion methods, in order to obtain reliable 2-D profiles of the electrical structure in the vicinity of the two earthquakes. A comparison of the two profiles indicates both similarities and differences in the deep crustal structure of the LMSf. West of the southwestern section, a crustal high conductivity layer (HCL) is present at about 10 km depth below the Songpan-Garzê block; this is about 10 km shallower than that under the middle section of the LMSf. A high resistivity body (HRB) is observed beneath the southwestern section, extending from the near surface to the top of upper mantle. It has a smaller size than the HRB observed below the middle section. In the middle section, there is a local area of decreased resistivity within the HRB but there is absence of this area. The 2013 Lushan earthquake occurred close to the eastern boundary of HRB and the Shuangshi-Dachuan fault, of which the seismogenic context has both common and different features in comparison with the 2008 Wenchuan event. On a large scale, the 2013 Lushan earthquake is associated with the HCL and deformation in the crust including HCL of the eastern Tibetan Plateau. In order to assess seismic risk, it is important to consider both the stress state and the detailed crustal structure in different parts of the LMSf.     

The deterministic nature of earthquake rupture

Understanding the earthquake rupture process is central to our understanding of fault systems and earthquake hazards. Multiple hypotheses concerning the nature of fault rupture have been proposed but no unifying theory has emerged. The conceptual hypothesis most commonly cited is the cascade model for fault rupture. In the cascade model, slip initiates on a small fault patch and continues to rupture further across a fault plane as long as the conditions are favourable. Two fundamental implications of this domino-like theory are that small earthquakes begin in the same manner as large earthquakes and that the rupture process is not deterministic--that is, the size of the earthquake cannot be determined until the cessation of rupture. Here we show that the frequency content of radiated seismic energy within the first few seconds of rupture scales with the final magnitude of the event. We infer that the magnitude of an earthquake can therefore be estimated before the rupture is complete. This finding implies that the rupture process is to some degree deterministic and has implications for the physics of the rupture process.     

<Emphasis Type="Italic">Ab initio</Emphasis> study of the effects of Ag/Mn doping on the electronic structure of LiFePO<Subscript>4</Subscript>

Based on density functional theory （DFT） of the first-principle for the cathode materials of lithium ion battery, the electronic structures of Li（Fe1-x）PO4 （Me = Ag/Mn, x = 0-0.40） are calculated by plane wave pseudo-potential method using Cambridge serial total energy package （CASTEP） program. The calculated results show that the Fermi level of mixed atoms Fe1-xAgx moves into its conduction bands （CBs） due to the Ag doping. The Li（Fe1-xAgx）PO4 system displays the periodic direct semiconductor characteristic with the increase of Ag-doped concentration. However, for Fe1-xMnx mixed atoms, the Fermi level is pined at the bottom of conduction bands （CBs）, which is ascribed to the interaction between Mn（3d） electrons and Fe（4s） electrons. The intensity of the partial density of states （PDOS） near the bottom of CBs becomes stronger with the increase of Mn-doped concentration. The Fermi energy of the Li（Fe1-xMnx）PO4 reaches maximum at x = 0.25, which is consistent with the experimental value of x = 0.20. The whole conduction property of Mn-doped LiFePO4 is superior to that of Ag-doped LiFePO4 cathode material, but the structural stability is reverse.     

Determination of free energy of protein folding on liquid-solid interface

Based on the fact that the stoichiometric displacement model for retention of solute and the total adsorption free energy of solute on a solid surface can be divided into two components, net adsorption and net desorbed energies, a new principle and an equation for calculating the free energy of protein folding, △△GF, on the solid surface are proposed. With high-performance hydrophobic interaction chromatography (HPHIC), an experimental method for determining the △△GF is established. Lysozyme and α-amylase have been selected as examples to test the new method, and their △△GF on the HPHIC stationary phase surface are found to be much higher than that reported from a solution. In addition, the △△GF of the two proteins are found to increase with the concentration of denaturing agent employed. The average standard deviations, ±4.7% for lysozyme and ±3.0% for α-amylase, indicate that the new method has a satisfactory reproducibility and reliability.