The Hilbert spectra resulted from HHT can provide more significant description of time-varying frequency composition and thus represent the non-stationarity of earthquake ground motion more accurately.

• 由HHT方法得到的Hilbert功率谱能清晰地显示随时间变化的频率特征,因而能更精确的表达地震动时程频域内非平稳的特性。