Co-seismic Response Characteristics of Water Level in Well Tangshan of Hebei,China Based on EEMD
Ensemble empirical mode decomposition(EEMD)can objectively and truly extract useful information from nonlinear and non-stationary signals,and the waveform signal characterized by water level in seismic observation well is also a typical nonlinear and non-stationary signal,so that EEMD has important application potential in obtaining the co-seismic response information of well water level.Taking well Tangshan in Hebei as an example,the advantages and disadvantages of EEMD for well water level analysis and processing through its co-seismic response of multiple well water levels from 2016 to 2023 were analyzed,the co-seismic response characteristics of well Tangshan were identified to teleseismic and near-seismic well water levels,and the seismic recording ability of well Tangshan was inferred by using the empirical formula of seismic energy density.The results show that after EEMD processing,the reconstruction of appropriate high-frequency components can suppress noise interference,which is more conducive to observing the co-seismic response characteristics of well water level.The oscillating co-seismic response caused by far-field large earthquakes can be identified and extracted objectively and truly.For the study of step-varying co-seismic response caused by near-field earthquakes,it is necessary to combine the original data to identify through high-frequency components.The second value of well water level observation data is more conducive to revealing the change of regional stress field.Due to the improvement of the recording accuracy of second value of observation data,the earthquake with energy density of 1.77×10-7 J·m-3 could be record by water level of well Tangshan.The sensitivity of observation wells to earthquakes in different orientations can be used to study the orientation of the fracture in which they are located.For far-field earthquakes over a certain distance,the co-seismic response frequency of well water level recorded by the well-aquifer system can calculate the natural vibration frequency of observation well within a certain range,and the natural vibration frequency of well Tangshan is close to the seismic Rayleigh wave.
co-seismic responsewell TangshanEEMDsecond value of observation datanatural frequencyseismic orientationfracture orientationseismic energy density
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维普
