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

摘要： 紫坪铺水库地震台网是离汶川M_S8.0地震震中最近的地震台网,记录了不可多得的地震事件资料。为讨论这些资料的精确度,将台网使用的地震记录仪的型号、硬件组成和性能指标与美国的RefTek地震记录仪进行了比较,并从地震记录数据处理结果方面进行了分析验证。结果表明,台网记录仪自身硬件带来的最大误差<1.8ms; 该台网记录的汶川M_S8.0地震震相拾取结果与美国的RefTek地震记录仪记录的结果相差0.02s。与综合四川台网得到的发震时刻比较,最大相差0.48s,最小相差-0.03s; 由包括该台网在内的21个台的P波到时和震中距绘制的时程图线性度较好。这说明,紫坪铺台网所用的地震记录仪所产生的误差,远比震相读取产生的误差小,亦比地震波传播过程中介质不均匀性造成的影响要小。该台网所用地震记录仪的时间精度完全能够满足现代地震分析需要。

关键词: 紫坪铺台网, 汶川M_S8.0地震, 时间准确性