Construction of the Technical System of Data Backup Centre for China Seismograph Network and Its Support to Wenchuan Earthquake Researches

Zheng, Xiaojing; Ouyang, Biao; Zhang, Dong-Ning; Yao, Zhixiang; Liang, Juhua; Zheng, Jie

doi:10.1002/cjg2.1387

Cited by 69 publications

(65 citation statements)

References 1 publication

(2 reference statements)

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“…Completed in early 2007, the new CEA seismic network consists of a backbone national seismograph network, 31 provincial networks, and several small aperture arrays with more than 1 000 stations including 850+ broadband stations (Zheng et al, 2009). The 1 000+ stations formed a large 2D areal array with an aperture ∼6 700 km from east to west and ∼3 500 km from north to south.…”

Section: Cearraymentioning

confidence: 99%

Imaging the mantle transition zone beneath eastern and central China with CEArray receiver functions

Wang

Niu

2011

Earthq Sci

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We analyzed a total of 37 427 receiver-function data recorded by national and regional broadband seismic networks of the China Earthquake Administration to study the mantle transition zone beneath eastern and central China. Significant topography on both the 410-km and 660-km discontinuities was clearly imaged in the 3D volume of CCP (common-conversion-point) stacked images that cover an area of 102.5 • E-122.5 • E and 22.0 • N-42.0 • N. 3D crustal and mantle velocity models were used in computing the Ps time moveouts to better image the absolute depths of the two discontinuities. We found that the 660-km discontinuity is depressed up to 25 km along the east coast of China, indicating the presence of the subducted Pacific slab in the region. More interestingly, a double 660-km was observed beneath the Huanghai Sea, which was not seen from the 410-km discontinuity. We found a strong and localized anomaly beneath the Quaternary Datong volcano located at the northeastern edge of the Ordos Plateau in North China. The 410-km is depressed by as much as 15 km beneath the volcano. If the amount of the depression is caused by unmodeled low velocity anomaly in the upper mantle, it requires either a strong (4%-8%) localized low velocity anomaly near the lithosphere-asthenosphere boundary or ∼1.5% low velocity column across the entire upper mantle above the 410-km. The latter could suggest a deep origin of the Datong volcano, although it was usually attributed to edge-driven convection by most of the literatures.

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Section: Cearraymentioning

confidence: 99%

Imaging the mantle transition zone beneath eastern and central China with CEArray receiver functions

Wang

Niu

2011

Earthq Sci

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“…We relocated the mainshock of Lushan earthquake using the waveform data provided by Data Backup Center of National Digital Seismic Network [14] with 'Sichuan-Yunnan traveltime table earthquake location software' [15,16]. The software takes into account the earth ellipticity, station elevation, topography and other factors, and is based on 3-D velocity discontinuities and 3-D velocity model.…”

Section: Mainshock Relocationmentioning

confidence: 99%

Relocation of the mainshock and aftershock sequences of M S7.0 Sichuan Lushan earthquake

et al. 2013

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The mainshock of April 20, 2013 Sichuan Lushan M S 7.0 earthquake was relocated using a 3-D velocity model. Double difference algorithm was applied to relocate aftershock sequences of Lushan earthquake. The locations of 2405 aftershocks were determined. The location errors in E-W, N-S and U-D direction were 0.30, 0.29 and 0.59 km on average, respectively. The location of the mainshock is 102.983°E, 30.291°N and the focal depth is 17.6 km. The relocation results show that the aftershocks spread approximately 35 km in length and 16 km in width. The dominant distribution of the focal depth ranges from 10 to 20 km. A few earthquakes occurred in the shallow crust. Focal depth profiles show fault planes dip to the northwest, manifested itself as a listric thrust fault. The dip angle is steep in the shallow crust and gentle in the deep crust. Although the epicenters of aftershocks distributed mainly along both sides of the Shuangshi-Dachuan fault, the seismogenic fault may be a blind thrust fault on the eastern side of the Shuangshi-Dachuan fault. Earthquake relocation results reveal that there is a southeastward tilt aftershock belt intersecting with the seismogenic fault with y-shape. We speculate it is a back thrust fault that often appears in a thrust fault system. Lushan earthquake triggered the seismic activity of the back thrust fault.Lushan earthquake, aftershock sequence, earthquake location, double difference location, Longmenshan fault Citation:Fang L H, Wu J P, Wang W L, et al. Relocation of the mainshock and aftershock sequences of Ms7.0

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“…Immediately after the mainshock, the China Earthquake Administration (CEA) installed a temporary network of portable seismometers to monitor aftershock activity ( Fig. A.1) (Zheng et al, 2009). The average spacing between stations is about 100 km, and is even 50 km in certain regions.…”

Section: Data and Analysismentioning

confidence: 99%

Strong aftershocks in the northern segment of the Wenchuan earthquake rupture zone and their seismotectonic implications

Zheng

Xie

et al. 2010

Earth Planet Sp

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More than 28,000 aftershocks have occurred since the 05/12/2008 Wenchuan earthquake, with dozens of them stronger than M 5. Since July, 2008, all the M > 5 earthquakes have occurred only in the northern segment of the rupture zone, suggesting obvious seismicity segmentation. We applied the double difference method to relocate all of the M > 3 aftershocks. After relocation, the aftershocks show a compact zone of seismicity, with a length of about 300 km and average width of 30 km, supporting that the hypothesis that the Beichuan-Yingxiu and Chaping-Linjiaan faults are the faults that ruptured in the earthquake. With the Cut and Paste (CAP) waveform inversion algorithm, we determined the source mechanism and focal depth of all the > M 5 aftershocks in the northern segments. The number of thrust events is close to the number of strike-slip events, but almost all of the events with thrust mechanism are distributed over the northern segment, while the aftershocks with strike-slip mechanism only occurred at the north-easternmost end, contrasting with eld observations of a substantial strikeslip component of surface rupture over the northern segment. The events with strike-slip mechanism occurred at depths up to 18 km, consistent with the lack of surface rupture in the north-easternmost section. However, since early August, very shallow events (2 km) with thrust mechanism have occurred, probably releasing the strain energy of the unruptured fault in the north-easternmost section. It seems that the seismic hazard potential of the northern segment is still quite high, and more studies are needed to resolve some of the discrepancy suggested by aftershock patterns and other observations.

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Construction of the Technical System of Data Backup Centre for China Seismograph Network and Its Support to Wenchuan Earthquake Researches

Cited by 69 publications

References 1 publication

Imaging the mantle transition zone beneath eastern and central China with CEArray receiver functions

Imaging the mantle transition zone beneath eastern and central China with CEArray receiver functions

Relocation of the mainshock and aftershock sequences of M S7.0 Sichuan Lushan earthquake

Strong aftershocks in the northern segment of the Wenchuan earthquake rupture zone and their seismotectonic implications

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