Co-seismic fault geometry and slip distribution of the 26 December 2004, giant Sumatra–Andaman earthquake constrained by GPS, coral reef, and remote sensing data

We analyze co-seismic displacement field of the 26 December 2004, giant Sumatra–Andaman earthquake derived from Global Position System observations,geological vertical measurement of coral head, and pivot line observed through remote sensing. Using the co-seismic displacement field and AK135 spherical layered Earth model, we invert co-seismic slip distribution along the seismic fault. We also search the best fault geometry model to fit the observed data. Assuming that the dip angle linearly increases in downward direction, the postfit residual variation of the inversed geometry model with dip angles linearly changing along fault strike are plotted. The geometry model with local minimum misfits is the one with dip angle linearly increasing along strike from 4.3oin top southernmost patch to 4.5oin top northernmost path and dip angle linearly increased. By using the fault shape and geodetic co-seismic data, we estimate the slip distribution on the curved fault. Our result shows that the earthquake ruptured ＊200-km width down to a depth of about 60 km.0.5–12.5 m of thrust slip is resolved with the largest slip centered around the central section of the rupture zone78N–108N in latitude. The estimated seismic moment is8.2 9 1022 N m, which is larger than estimation from the centroid moment magnitude（4.0 9 1022 N m）, and smaller than estimation from normal-mode oscillation data modeling（1.0 9 1023 N m）.

Effect of adsorption-induced matrix swelling on coal permeability evolution of micro-fracture with the real geometry

Gas transport in coal induces effective stress variation,matrix swelling/shrinkage,and significantly affects matrix and fracture deformation,resulting in porosity and permeability evolution.However,the heterogeneity and anisotropy of coal are neglected in dual porosity models,which can lead to the deviation from the real physical mechanisms.To uncover the permeability evolution,especially the influence of dynamic matrix-fracture interaction for real fracture distribution,advanced virtual simulation is proposed.In this study,real fracture geometry is taken into account in the physical model based on the CT-scan image,while the mathematical models for coal deformation and gas flow are established.Our calculations are verified against a long-term experimental data under the same boundary condition.Accordingly,the real matrix-fracture interaction caused by adsorption-induced matrix deformation has been visually exhibited,and some new insight into the behavior of fracture permeability in real materials is offered.The results indicate the non-uniform distribution of fracture geometry is responsible for the nonmonotonic change of permeability.It also found that injection pressure,Langmuir strain constant and initial matrix permeability have important influences on the fracture permeability evolution.This research provides valuable insight into the understanding of the permeability change for the real fracture spatial distribution in coal.

Analysis on Stochastic Passage Characteristics for Gun Barrel in Shooting Domain

Aiming at some weapon systems with shooting domain,the stochastic passage characteristics of the barrel were studied.On the basis of the exact definition of the stochastic passage characteristics,its opportunity-awaiting time,residence time and stochastic passage period were given by using the transition probability matrix,and they all obeyed the geometry distributions.Their means and variances were also derived,and the relations between the time indexes and the structure and parameters of weapon control system were established.Finally,the creditability of the conclusions was verified by the test data of weapon system in proving ground.