Time-frequency analysis of seismic acceleration based on Hilbert-Huang transform:a case study of Luding Ms6.8 earthquake
Deep canyons are developed in western Sichuan,and earthquakes occur frequently.It is of great significance to study the vibration energy distribution of seismic waves on high and steep slopes in this area.According to the Luding Ms6.8 seismic acceleration data collected by the self-built Luding Lengzhuguan Seismic Monitoring Station,using the Hilbert-Huang transform method to analyze its time-frequency information,this method breaks through the limitations of traditional time-frequency analysis methods such as Fourier transform and wavelet transform,and can effectively analyze non-stationary signals with short-term mutations,revealing that:(1)the seismic wave vibration energy of this earthquake has obvious directionality,the seismic vibration energy in the horizontal direction is stronger than that in the vertical direction,and the vibration energy is stronger in the ultra-low frequency(0～5 Hz)range than in the median low frequency(5～7 Hz)range;(2)The seismic response energy of a thin mountain ridge is stronger than that of a thick mountain body,and the seismic vibration energy is strongest at the protruding terrain of the ridge slope top;(3)Terrain factors have a great impact on the vibration energy of seismic waves.The vibration energy at the top of slope is stronger than that at the slope break.The vibration energy at the slope break is more widely distributed in the frequency range.At the same elevation,the vibration energy at the convex terrain at the top of the ridge is stronger than that at the slope.When an earthquake occurs,the top of high and steep slopes,thin ridges and micro-topography bulges are more prone to coseismic geological disasters.
Luding Ms6.8 earthquakeHilbert-Huang transformSeismic vibration energyHigh and steep slope
万方数据
