An inversion of site response and Lg attenuation using Lg waveform

Abstract

Based on spectral ratio method, a joint inversion method was used to obtain parameters of Lg wave attenuation and site response. The inversion method allows simple and direct (two-parameter) determination of Lg wave attenuation and site response from sparse spectral data, which are not affected by radiation pattern factor and different response of same instrument after geometrical spreading. The method was used successfully for estimating site response of stations of Zhejiang Seismic Network and measuring Lg wave attenuation. The study is based on 20 earthquakes occurred in northeast of Taiwan with magnitude M S 5.0~6.7 and 960 seismic wave records from 16 stations in Zhejiang area from 2002 to 2005. The parameters of site response and Lg attenuation were calculated with a frequency interval of 0.2 Hz in the range of 0.5 Hz to 10 Hz. Lg wave attenuation coefficient corresponding to U-D, E-W and N-S components are γ ( f )=0.00175 f 0.43485 , γ ( f )=0.00145f 0.48467 and γ ( f )=0.0021f 0.41241 , respectively.It is found that the site response is component-independent. It is also found that the site response of QIY station is significant above the frequency of 1.5 Hz, and that the site response of NIB station is low for most frequency

An Inversion of Site Response and Medium Parameters of Shaanxi Area Using Records of the Wenchuan Aftershocks

“…In the range of 0.5~7Hz, the Lg wave attenuation coefficient corresponding to UD, EW and NS components are γ(f)=0.0045f 0.327 , γ(f)=0.00335f 0.417 and γ(f)=0.00356f 0.393 , respectively. These are similar to that of Zhejiang region, but the attenuation with frequency is slower than North-Center America, Canada [6] and northernmost North Korea [7].…”

“…The Lg group velocity range (3.65 km/s to 2.6 km/s) is closely compatible with those considered by the others [6], After removal of the mean and trend, the Lg window waveforms are padded with zeros to the next nearest power of 2 to allow the application of the Fast Fourier Transform algorithm. Five percent of the windows are applied at the end of each windowed record.…”

“…This leads to the results lower than 1 at this frequency for estimated station. This is obviosly in Atkinson's method [2,6].…”

“…In order to accurately obtain all parameters, it is necessary to distinguish hypocentral effect, propagation path and site response [6]. Assuming that, ① in the studied time interval and studied areas where seismic wave passed through and no significant tectonic movement occurred, attenuation coefficient is stable; ② The site response only depends on frequency, and is independent of other factors included in equation of the displacement spectral amplitude A of Lg wave, thus for any earthquake, the ratio of spectral amplitude recorded at two stations is only affected by frequency; and ③ Among these stations, there must be a station, of which the site response is ideal to a frequency and response amplitude is taken to be one unit.…”

Study on Emission Control of Dioxins by Thermal Decomposition

“…Being the largest developing country, China generates annually 170 billion kg of municipal solid waste (MSW), accounting for 26.5% of the total production of the world [1]. The lack of landfill sites for the wastes has forced some big cities to choose the incineration as an alternative technology to treat MSW.…”