| The 2008 Ms8.0 Wenchuan earthquake ruptured the middle and northern segments of the Longmenshan fault zone(LMSFZ)at the eastern margin of the Tibetan Plateau.The Wenchuan Earthquake is one of the most severe earthquakes in recent years,causing huge casualties and property losses.The North-South Seismic Zone of China enters into a new active period of strong earthquakes.LMSFZ is a quake-prone,mountainous region so the seismograph network can accumulate massive amounts of waveform data.In this study,we used the continuous waveform data recorded by the State Earthquake Information Service Digital Media Center(SEIS DMC)between August 2007 and December 2014 to search for repeating earthquakes along the Longmenshan fault zone(LMSFZ).We obtained 2790 repeating earthquakes by using crosscorrelation analysis of waveform data,based on the principle that repeating events recorded by no less than 3 stations with cross-correlation coefficient C>0.8.With the assumption that the repeating events were separated by no more than 1 km,the network-measured apparent distances of repeating events indicates the routine earthquake location error of the seismograph network around the LMSFZ.It is observed that the “horizontal location error” of seismograph network nearby LMSFZ is estimated to be below 5 km,with the average of 2.8 km.And the average location accuracy of the southwestern segment of LMSFZ is better than the central-northern segment of the LMSFZ.The results also show that the “vertical location error” is estimated with the average of 10 km.We add strict constraint condition to relocate and identify the repeating earthquakes in order to estimate the slip rates at seismogenic depths,the slip rates can reflect the quantitative description of the deep deformation.Our result shows that the LMSFZ vary from 2.8 ~11.8 mm/a at the depth range of 0 ~ 26 km,it also shows that the slip rates of the middle-northern part of LMSFZ are different at different seismogenic depths. |
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