怀来地震台定点形变观测转折异常的调查与分析

2020年3月12日河北省怀来地震台伸缩仪、水管仪、垂直摆和水平摆同步出现快速转折破年变的变化,针对这些异常,从观测和供电系统、洞室环境、气象因素等方面开展现场实地调查与异常核实工作。通过对观测环境的勘查,发现3月10日在观测山洞西侧约80 m处,原有的2排平房因拆迁被拆除。应用点载荷模型对拆迁房屋引起的形变理论值进行计算分析发现,应变、倾斜受载荷干扰的理论值与仪器记录异常幅度在量级上一致。因此,此次形变异常为非地震前兆异常,与房屋拆迁引起的荷载变化有关。

Investigation and Analysis of Turning Anomalies in Fixed-point Deformation at Huailai Seismic Station

On March 12,2020,the extensometer,the water tube meter,the vertical pendulum and the horizontal pendulum at Huailai Seismic Station in Hebei Province simultaneously appeared a rapid turning,breaking the annual variation.In view of these anomalies,field investigation and anomaly verification were carried out from the aspects of observation and power supply system,chamber environment,meteorological factors,etc.Through investigation of observation environment,it was found that 2 rows of old bungalows located about 80 meters west of observation cave on the 10th day were demolished due to demolition.The theoretical values of deformation caused by house demolition were calculated with the point load model.It was found that the theoretical values of strain and inclination disturbed by load were in agreement with the abnormal amplitude recorded by the instrument.Therefore,this deformation anomaly is a non-seismic precursor anomaly and is related to the load changes caused by house demolition.