South China Sea Typhoon Hagibis enhanced Xinfengjiang Reservoir seismicity

There was an evident increase in the number of earthquakes in the Xinfengjiang Reservoir from June to July 2014 after the landing of Typhoon Hagibis.To understand the spatial and temporal evolution of this microseismicity,we built a high-precision earthquake catalog for 2014 and relocated 2275 events using recently developed methods for event picking and catalog construction.Seismicity occurred in the southeastern part of the reservoir,with the preferred fault plane orientation aligned along the Heyuan Fault.The total seismic energy peaked when the typhoon passed through the reservoir,and seismicity correlated with typhoon energy.In contrast,a limited seismic response was observed during the later Typhoon Rammasun.Combining data regarding the water level in the Xinfengjiang Reservoir and seismicity frequency changes in the Taiwan region during these two typhoon events,we suggest that typhoon activity may increase microseism energy by impacting fault stability around the Xinfengjiang Reservoir.Whether a fault can be activated also depends on how close the stress accumulation is to its failure point.

Three dimensional shear wave velocity structure of the crust and upper mantle beneath China from ambient noise surface wave tomography

We determine the three-dimensional shear wave velocity structure of the crust and upper mantle in China using Green＇s functions obtained from seismic ambient noise cross-correlation. The data we use are from the China National Seismic Network, global and regional networks and PASSCAL stations in the region. We first acquire cross-correlation seismograms between all possible station pairs. We then measure the Rayleigh wave group and phase dispersion curves using a frequency-time analysis method from 8 s to 60 s. After that, Rayleigh wave group and phase velocity dispersion maps on 1°by 1°spatial grids are obtained at different periods. Finally, we invert these maps for the 3-D shear wave velocity structure of the crust and upper mantle beneath China at each grid node. The inversion results show large-scale structures that correlate well with surface geology. Near the surface, velocities in major basins are anomalously slow, consistent with the thick sediments. East-west contrasts are striking in Moho depth. There is also a fast mid-to-lower crust and mantle lithosphere beneath the major basins surrounding the Tibetan plateau （TP） and Tianshan （Junggar, Tarim, Ordos, and Sichuan）. These strong blocks, therefore, appear to play an important role in confining the deformation of the TP and constraining its geometry to form its current triangular shape. In northwest TP in Qiangtang, slow anomalies extend from the crust to the mantle lithosphere. Meanwhile, widespread, a prominent low-velocity zone is observed in the middle crust beneath most of the central, eastern and southeastern Tibetan plateau, consistent with a weak （and perhaps mobile） middle crust.

Major Miocene geological events in southern Tibet and eastern Asia induced by the subduction of the Ninetyeast Ridge

Cenozoic adakitic rocks in the Gangdese changed from barren continental melts to ore-forming slab melts at * 23 Ma. The distribution and chemical characteristics of the ore-forming adakites point to an association with the Ninetyeast Ridge. The subduction of the thick,rigid Ninetyeast Ridge changed the geometry and rheology of the eastern Tibetan Plateau lithosphere and asthenosphere, restrained the eastward escape of asthenospheric mantle as well as continental fragments, and promoted the uplift and building of the Tibetan Plateau, which consequently changed the tectonic and climatic regimes in eastern Asia.

Origin of ULVZs near the African LLSVP: Implications from their distribution and characteristics

Ultra-low velocity zones(ULVZs)provide important information on the composition and dynamics of the core-mantle boundary(CMB).However,their global distribution and characteristics are not well constrained,especially near African large low-shear velocity provinces(LLSVPs).Here,we used ScS precursor(SdS)and postcursor(ScscS)phases recorded by various seismic networks in Africa and South America to investigate the ULVZ characteristics underlying the South Atlantic Ocean.We found no evidence of ULVZs near the SE boundary of South America,but an ULVZ was found within the SW boundary of the African LLSVP,with thicknesses ranging from 11–18 km and reductions in S-wave velocities of 18%–34%.Our results,combined with the global distribution of ULVZs,suggest that thermal activity may be essential to ULVZ formation.Moreover,subducted slab and mantle flow may also play a key role,depending on the location of the ULVZs.

Topography effect on ambient noise tomography using a dense seismic array

With the rapid increase of dense seismic array deployment, more and more ambient noise studies have been applied on short period surface waves tomography. For arrays with inter-station distance of several hundred meters,the effect of surface topography has to be considered. In this study, we investigate topography effect on ambient noise surface wave tomography using synthetic data from different topographic models. Our travel times are synthetized considering surface topography, and shear wave inversions are performed by incorporating and not incorporating topography respectively. Our inversion results suggest that topography does affect subsurface shear wave velocity inversion. If topography is not considered, although the pattern of the structure may be recovered reasonably well, the depth distribution of velocity structure can be distorted. The maximum distortion depth is generally correlated with the relief of the topography and the amplitude of the velocity anomalies. Finally, our example of real data inversion in a mountain area demonstrates good correlation between shear velocity and the geological settings, as well as the core sample in that area.

PKM2 controls the degranulation of secondary and tertiary granules in neutrophils by phosphorylating SNAP-23

Polymorphonuclear neutrophils(PMNs)possess multiple distinct types of cytoplasmic granules:secondary granules,tertiary granules,and azurophil granules[1].It has been suggested that PMN degranulation is controlled by exocytotic machinery comprising membrane-specific SNARE proteins,soluble N-ethylmaleimide sensitive factor(NSF)and soluble NSF-attaching proteins[2].