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Guo T.-T.,Shandong Institute of Earthquake Engineering | Guo T.-T.,China Earthquake Administration | Xu X.-W.,China Earthquake Administration | Xing H.-L.,University of Queensland | Yu G.-H.,China Earthquake Administration
Dizhen Dizhi

In this paper, adopting nonlinear finite-element method for faults with frictional contact, single fault and conjugate faults are calculated and compared respectively. And conjugate faults system is analyzed about its structural significance, combined with preparation and occurrence of strong earthquakes in the capital circle region. Study shows that seismogenic process of typical conjugated fault system from lock to unlock is well explained by Coulomb friction criteria, and unstable events can take place alternately along conjugate faults. The slip behavior of seismogenic tectonic model of great earthquake composed of two conjugate faults is verified. The numerical simulation as well as the analysis and discussion on the results provide scientific basis for earthquake forecasting and monitoring in areas where conjugate faults have developed. ©, 2015, State Seismology Administration. All right reserved. Source

Gao Z.,China Earthquake Administration | Zhang R.,China Earthquake Administration | Wu Q.,China Earthquake Administration | Zhang G.,Shandong Institute of Earthquake Engineering
Acta Seismologica Sinica

It is highly debated on whether the subduction Pacific slab becomes stagnant in the transition zone and extends horizontally or it penetrates into the lower mantle when the leading of the Pacific slab reaches to a depth of 660 km beneath northeast China. Taking advantage of the sensitivity of P-SV conversions to the velocity discontinuities, we employ receiver function method to constrain the topography variation of the 660 km discontinuity beneath northeast China using common conversion point (CCP) stacking. The teleseismic data recorded by 136 permanent stations operated by CDSN in northeast China are used in this study. Our results show that the 660 km discontinuity deepening more than 20 km was observed in the region to the south of 44°N with length about 400 km in the east-west direction. The local depression of the 660 km discontinuity supports that the Pacific subduction slab has reached northeast China and it may penetrates into the lower mantle locally. ©, 2015, Acta Seismologica Sinica Press. All right reserved. Source

Zhang G.,China Earthquake Administration | Zhang G.,Shandong Institute of Earthquake Engineering | Wu Q.,China Earthquake Administration | Li Y.,China Earthquake Administration | And 3 more authors.
Acta Seismologica Sinica

Using teleseismic events recorded by 65 broad-band digital seismic stations during June 2009 to June 2011 in Northeast China, we calculated receiver functions by conducting maximum entropy deconvolution in time domain, and obtained the crustal anisotropy parameters by using the improved shear-wave splitting analysis. The result shows that in Northeast China, the dominant direction of fast wave polarity is approximately in NW-SE in this region, and the time delay between the fast and slow waves is 0.15-0.3 seconds. But the fast wave polarity direction is in NE-SW beneath other 7 stations, possibly due to the effect of local complex structure. Through a comparison study we find that the polarization direction of the fast wave is nearly perpendicular to the direction of principal compressive stress, and is approximately the same as the direction of the Eurasian plate movement and the result of SKS/SKKS analysis. It can be concluded that our result has revealed the tensile stress and the anisotropy may come from the middle and lower part of the crust in this region. Source

Zhang R.,China Earthquake Administration | Gao Z.,China Earthquake Administration | Wu Q.,China Earthquake Administration | Xie Z.,China Earthquake Administration | Zhang G.,Shandong Institute of Earthquake Engineering

Seismic data from northeast (NE) China and the Sino-Korean craton were combined to image the upper mantle discontinuities at 410 and 660 km. Fine-scale topographic variations on these two discontinuities provide important clues for both delineating geometry of the subducting Pacific slab particularly at arc-arc junction and interpreting regional Cenozoic intraplate volcanism. We used over 90,000 receiver functions from 1916 teleseismic earthquakes recorded by 584 broadband seismic stations, primary those of temporary seismic arrays. We found the average depths of the two discontinuities to be 410 km and 672 km, respectively, beneath the study area. Results show that the 660-km discontinuity is strongly depressed by about 20-30 km in a narrow region beneath and around the Changbaishan volcano, consistent with the results of previous receiver function studies. In contrast, much of the Sino-Korean craton exhibits typical transition zone thickness (~. 260 km) and thus offers no evidence of a stagnated Pacific slab. Our results also reveal an elevated 660-km discontinuity and a thinner transition zone both to the west of the observed depression region and beneath the Kuril-Japan arc junction. This feature is most likely due to a tearing of the descending Pacific plate at both its leading and junction edges. An additional elevated 660-km discontinuity together with a thinner transition zone appears in the vicinity of the Dariganga lava field, supporting interpretations of a deep-rooted mantle plume. Our observations of an elevated 410-km discontinuity and a thicker transition zone correlate spatially with the diffuse distribution of volcanism around Hannuoba, Aershan and Wudalianchi. This correlation may suggest lithospheric removal as a mechanism for these magmatic activities. © 2016 Elsevier B.V. Source

Ting-ting G.,Shandong Institute of Earthquake Engineering | Ting-ting G.,China Earthquake Administration | Xu X.-W.,China Earthquake Administration | Yu G.-H.,China Earthquake Administration
Applied Mechanics and Materials

2008 Ms8.0 Wenchuan earthquake produced Strong surface rupture and deformation, triggered geological disasters: Collapse and landslide, and brought about serious buildings damage and casualties. Wenchuan earthquake surface rupture, secondary geological disasters and buildings damage were investigated on-site. Disasters characteristics of the earthquake were discussed, and relationship between buildings damage distribution and seismogenic fault of Wenchuan earthquake was discussed. In light of seismic protection and the Code for Seismic Design of Buildings, typical buildings damage and its causes are analyzed and discussed from following respects of buildings location, seismic design and buildings construction. Corresponding seismic measures are suggested. © (2012) Trans Tech Publications, Switzerland. Source

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