关键词: 紫坪铺台网, 汶川M_S8.0地震, 时间准确性

Abstract: The Zipingpu Reservoir Seismic Network is the nearest network to the epicenter of the M_S8.0 Wenchuan earthquake and it recorded the rare data of this earthquake event. In order to discuss the accuracy of these data,we compared the seismometers used in this network in terms of the types,hardware components and performance index with the US RefTek seismometer and analyzed the processing results of the earthquake records for the verification. Results show that the seismometer of the network has a maximum error of <1.8ms. There is a difference of 0.02s in the phase picking result of the M_S 8.0 Wenchuan earthquake from the recordings of this network with that from the US RefTek recordings. And compared with the earthquake occurrence time determined from the recordings of the Sichuan seismic network,the maximum difference is 0.48s,and the minimum -0.03s. The time-history curve plotted using P-wave arrivals and epicentral distances of 21 stations(including the network stations)has a good linearity. This indicates that the error generated from the seismometers used in Zipingpu network is far less than the error from phase picking,and the impact of it is also smaller than that caused by the heterogeneity of medium in seismic wave propagation. The time accuracy of the seismometer used in this network can satisfy completely the needs of modern earthquake analysis.

Key words: Zipingpu network, Wenchuan earthquake, time accuracy