Lg-wave attenuation and site response in Ningxia region

Based on 131 seismic waveform data recorded by 15 digital seismic stations in Ningxia region and its neighboring areas from 2008 to 2017, this paper analyzed Lg wave attenu-ation and site response at the frequencies ranging from 1 to 7 Hz by using the combined inversion method of seismic wave attenuation and site response. The relationship between the seismic wave attenuation quality factor Q（ f ） and the frequency f for each component was calculated by using 1 069 Lg waveforms in the velocity window of 2.2—3.6 km/s. The results show that the Q₀ of vertical, west-east and north-south components are 237.1, 201.8 and 245.9, and the frequency exponent of the Q（ f ） are 0.44, 0.52 and 0.44, respectively. The result of this area is consistent with the results of the other seismically active regions in the world. Furthermore, in time domain the analysis of Q（ f ） suggests that the attenuation characteristics of crustal medium in this region do not change during the studied period, and the maximum response amplitude of 15 stations was not more than 6 in the region.