Lg attenuation in northeast China using NECESSArray data

The 127 station NorthEast China Extended SeiSmic Array (NECESSArray) provides large quantities of high quality seismic data in northeast China that allow us to resolve lateral variations of Lg Q or crustal attenuation at 1 Hz (Qo) to 2.0° or greater. Using the reverse two-station/event method with 11 642 Lg path-amplitudes from 78 crustal earthquakes, we obtain a 2-D tomographic image of Lg Q_o with values ranging from ~50 to 1400. A high degree of detail in the lateral variation of Lg attenuation is revealed in our tomographic image. High Q_o regions are found in the Great Xing'an, Lesser Xing'an and Songen-Zhangguangcai Ranges. Low Q_o regions are observed in the Songliao, Sanjiang and Erlian Basins. The lowest Q_o is found near the Wudalianchi volcanic field and other Quaternary volcanic fields, the southern Songliao Basin, the western edge of the Erlian Basin and the Sanjiang Basin. Low Q_o values are measured for paths that cross sedimentary basins with thick, unconsolidated sediments. Most of the high Lg attenuation in the Songliao Basin correlates reasonably well with low crustal Rayleigh wave phase velocity anomalies. The highest attenuating regions also correlate well with regions of Holocene volcanism.