Rayleigh Wave Attenuation Tomography in the Crust of the Chinese Mainland

In this study, we report a first major effort to measure surface wave amplitudes and to map attenuation structures of the Chinese mainland with dense modern broadband seismic networks in the country. We developed a method of phase-matched filtering to automatically extract fundamental-mode Rayleigh waves and to measure the spectral amplitudes. The results are compatible with those from the previous manual method with great improvement in efficiency. Using the automatic method, we extracted a large quantity of the amplitudes of Rayleigh waves at periods of 10 and 20 s recorded by 141 broadband stations from the China Digital Seismograph Network and 656 broadband stations from the China Regional Seismic Network. We performed tomographic inversions using the method of two-station amplitude ratios and obtained images of the surface wave attenuation maps at periods of 10 and 20 s for the Chinese mainland. The tomographic model resolution reaches 1–2° in central and eastern China, 3–5° in western China, and 5° in the southeastern margin of the Tibetan Plateau and northeastern China. The tomographic results demonstrate good correspondence with geological structures. The distribution of strong historical earthquakes indicates that in the Chinese mainland, these earthquakes occurred mainly in high-attenuation areas or the junctions between high- and low-attenuation areas.