Waveform inversion and analysis of an unusual earthquake swarm in the Boshan mining area, Shandong Province, China Moment tensor solutions were retrieved for the earthquake swarm that occurred during November and December 2010 in the Boshan mining area,Shandong Province,China.The results showed that the double-couple components in the source mechanisms were higher at the beginning of the swarm and consisted mainly of shear faulting controlled by tectonic stress.The subsequent events had significant non-double-couple components,indicating tensile faulting.The double-couple components predominately presented as normal faulting and the P axes were orientated almost vertically.The slip vectors of the swarm events were relatively stable.With reference to the tectonic features near the epicenter,we concluded that the swarm was a result of subordinate fault motion related to the Wangmu Mountain fault and that high-pressure pore fluids played a crucial role in the activity of the earthquake swarm.
SplitRFLab： A MATLAB GUI toolbox for receiver function analysis based on SplitLab We add new modules for receiver lunction(RF) analysis in SplitLab toolbox,which includes the manual RF analysis module,automatic RF analysis and related quality control modules,and H-k stacking module.The updated toolbox(named SplitRFLab toolbox),especially its automatic RF analysis module,could calculate the RFs quickly and efficiently,which is very useful in RF analysis with huge amount of seismic data.China is now conducting the ChinArray project that plans to deploy thousands of portable stations across Chinese mainland.Our SplitRFLab toolbox may obtain reliable RF results quickly at the first time,which provide essentially new constraint to the crustal and mantle structures.
Evaluation of earthquake parameters used in the Indonesian Tsunami Early Warning System Twenty-two of a total of 30 earthquake events reported by the Indonesian Agency for Geophysics.Climatology and Meteorology during the time period2007-2010 were falsely issued as tsunamigenic by the Indonesian Tsunami Early Warning System(Ina-TEWS).These 30 earthquakes were of different magnitudes and occurred in different locations.This study aimed to evaluate the performance of the Ina-TEWS using common earthquake parameters,including the earthquake magnitude,origin time,depth,and epicenter.In total.298 datasets assessed by the Ina-TEWS and the global centroid moment tensor(CMT) method were assessed.The global CMT method is considered by almost all seismologists to be a reference for the determination of these parameters as they have been proved to be accurate.It was found that the earthquake magnitude,origin time,and depth provided by the Ina-TEWS were significantly different from those given in the global CMT catalog,whereas the latitude and longitude positions of the events provided by both tsunami assessment systems were coincident.The performance of the Ina-TEWS.particularly in terms of accuracy,remains questionable and needs to be improved.
A way of estimating the characteristic slip displacement During the ruptures of an earthquake,the strain energy.△E,.will be transferred into,at least,three parts,i.e..the seismic radiation energy(E_s),fracture energy(E_g),and frictional energy(E_f),that is,△E = E_s + E_g + E_f.Friction,which is represented by a velocity- and state-dependent friction law by some researchers,controls the three parts.One of the main parameters of the law is the characteristic slip displacement.D_c.It is significant and necessary to evaluate the reliable value of D_c from observed and inverted seismic data.Since D_c controls the radiation efficiency.η_R = E_s/(E_s+ E_g),the value of η_r is a good constraint of estimating D_c.Integrating observed data and inverted results of source parameters from recorded seismograms.the values of E_s and E_g of an earthquake can be measured,thus leading to the value of η_R.The constraint used to estimate the reliable value of D_c will be described in this work.An example of estimates of D_c.based on the observed and inverted values of source parameters of the September 20,1999 M_S 7.6 Chi-Chi(Ji-Ji).Taiwan region,earthquake will be presented.
Out-of-plane （SH） soil-structure interaction： a shear wall with rigid and flexible ring foundation Soil-structure interaction(SSI) of a building and shear wall above a foundation in an elastic half-space has long been an important research subject for earthquake engineers and strong-motion seismologists.Numerous papers have been published since the early 1970s;however,very few of these papers have analytic closed-form solutions available.The soil-structure interaction problem is one of the most classic problems connecting the two disciplines of earthquake engineering and civil engineering.The interaction effect represents the mechanism of energy transfer and dissipation among the elements of the dynamic system,namely the soil subgrade.foundation,and superstructure.This interaction effect is important across many structure,foundation,and subgrade types but is most pronounced when a rigid.superstructure is founded on a relatively soft lower foundation and subgrade.This effect may only be ignored when the subgrade is much harder than a flexible superstructure:for instance a flexible moment frame superstructure founded on a thin compacted soil layer on top of very stiff bedrock below.This paper will study the interaction effect of the subgrade and the superstructure.The analytical solution of the interaction of a shear wall,flexible-rigid foundation,and an elastic halfspace is derived for incident SH waves with various angles of incidence.It found that the flexible ring(soft layer)cannot be used as an isolation mechanism to decouple a superstructure from its substructure resting on a shaking half-space.