西安台新山洞两套倾斜仪观测数据对比分析

COMPARATIVE ANALYSIS ON OBSERVATION DATA OF TWO SETS OF INCLINOMETER IN NEW CAVE OF XI’AN SEISMOLOGICAL STATION

西安地震台新山洞于2019年建成,覆盖层较厚、观测环境优良,内部日温度、年温度变化均符合形变仪器观测环境要求。通过对2020~2021年新山洞架设的两套地倾斜仪(VP和DSQ)观测资料进行对比分析,得出以下结论:(1)VP型宽频带倾斜仪数据完整率和连续率均大于99%,DSQ型水管倾斜仪2020年数据连续率和完整率小于99%。(2)两套地倾斜仪器都能清晰记录到固体潮汐,VP型宽频带倾斜仪两个测向记录波形较好,两套仪器均无明显年变形态,水管倾斜仪北南和东西向数据漂移较大,北西向波形较稳定。(3)DSQ型水管倾斜仪观测精度、噪声水平明显高于VP型宽频带倾斜仪。(4)新山洞覆盖层较厚,强降雨、大风等自然环境变化对观测没有明显影响。(5)以青海果洛州玛多县Ms7.4地震、青海海北州门源县Ms6.9地震为例,分析表明VP型宽频带倾斜仪记录到的同震变化较DSQ型水管倾斜仪时间早、幅度大、持续时间长,这与观测仪器的基线长度、输入信号的频率等有关。

The new Cave of Xi’an Seismic Station was completed in 2019,with a thick coverage layer and excellent observation environment.The daily and annual temperature changes inside meet the requirements of deformation instrument observation environment.By comparing and analyzing the observation data of two sets of ground inclinometers(VP and DSQ)installed in the new cave from 2020 to 2021,it is concluded that:(1)The completeness and continuity of the VP vertical pendulum data are both greater than 99%,while the continuity and completeness of the DSQ water pipe instrument data in 2020 are less than 99%.(2)The two sets of ground tilt instruments can clearly record the solid tide.The waveform of the two DF records of the VP broadband tiltmeter is good,and there is no obvious annual change in the two sets of instruments.The data of the water tube instrument in the north-south and east-west directions drift greatly,and the waveform in the north-west direction is relatively stable.(3)The observation accuracy and noise level of the DSQ type water pipe inclinometer are significantly better than those of the VP type broadband inclinometer.(4)The cover layer of the new cave is relatively thick,and natural environmental changes such as heavy rainfall and strong winds have no significant impact on observation.(5)Taking the Ms7.4 earthquake in Maduo County,and the Ms6.9 earthquake in Menyuan County as examples,the analysis shows that the co-seismic changes recorded by the VP vertical pendulum are earlier,larger and longer than those recorded by the DSQ water tube instrument,which are related to the baseline length of the observation instrument and the frequency of the input signal.