五指山台水管倾斜仪北南向变化的异常判定

五指山台DSQ水管倾斜仪北南向自2017年5月持续南倾。排除观测系统、洞室温度、辅助观测资料情况和周围环境因素变化等多方面原因，利用观测资料内精度质量评价分析、数字化前兆异常识别等方法，结合GPS及重力场变化，综合认为，五指山地震台DSQ水管倾斜仪北南向南倾变化为正常区域背景变化趋势，非前兆异常现象。

Abnormal determination of north-south component of water pipe tiltmeter at Wuzhishan station

The north-south component of the DSQ water pipe tiltmeter at Wuzhishan station has been tilting southward continuously since May 2017. We eliminate various reasons such as the deformation observation system of the Wuzhishan station, the temperature of the cavern, the auxiliary observation data and the changes in surrounding environmental factors, and use the methods of the evaluation and analysis of the quality of the ground tilt observation data and the recognition of digital precursory anomalies. Combined with GPS and gravity field changes, it is concluded that the south tilt of DSQ water pipe tiltmeter at Wuzhishan station may be  a normal regional background change trend, not a precursor anomaly.