Ground Motion and Site Characteristics Evaluation Using Hilbert-Huang Transform Method Based on Light-Moderate Earthquakes

Compared with strong earthquakes (Ms ≥ 6.0), light-moderate 4–5.9) occurred more frequently and distributed widely, rich ground motions have been collected around world. It provides a solid data base for the investigation on motion regional site characteristics which are closely related to seismic geological disaster. We chose two in China as study cases. Based Hilbert-Huang transform, we analyzed time-frequency domain. Using stable coda wave marginal spectrum of it based horizontal vertical Fourier spectral ratio (HVSR) method, clarified. Result shows that amplitude (instantaneous frequency energy) is mainly concentrated within 20 Hz at stations close epicenter. The energy will change from concentration divergence time decrease increase epicenter distance under soil condition. Two present low prominent characteristic (1.075–2.45 Hz). Hilbert layer about 3 times greater than rock when can also amplify instantaneous energy. predominant each station 3.6–6.2 Hz. frequencies lower sites would not produce resonance effects. result provide meaningful references later works application earthquakes.