2012年2—6月乾陵地震台钻孔体应变多次记录到不明原因的大幅张性突跳，采用HHT方法对其边际谱特征进行分析，并与山东长清地震台体应变因电源不匹配所产生的干扰信号的边际谱特征进行对比。结果表明，二者具有较好的相关性。据此推断，造成此次应变异常的主要原因是电源问题。

 The unusually extensional strain steps with large amplitudes were repeatedly recorded by dilatometer at Qianling seismic station from February 2012 to June 2012. The Hilbert—Huang transform (HHT) is used to obtain the characteristics of Hilbert marginal spectra of these strain anomalies. Then, we further compared the analytical result to the Hilbert marginal spectra of the disturbed strain changes induced by power mismatching recorded at Changqing seismic station. Analytical results generally show that their characteristics of Hilbert marginal spectra have a good agreement. This suggests that the strain anomaly observed at Qianling seismic station was principally caused by power problem.