Clear PKIKP precursors were observed from the Lanzhou CTBTO seismic array.We measured their incident angles,arriving azimuths and differential travel times with respect to the PKIKP arrivals using array analysis techn...Clear PKIKP precursors were observed from the Lanzhou CTBTO seismic array.We measured their incident angles,arriving azimuths and differential travel times with respect to the PKIKP arrivals using array analysis techniques.These measurements allowed us to locate the scatterers that generated the observed precursors.We found that the scatterers are located in the lowermost mantle beneath eastern Tibet,which is featured by a high-velocity anomaly based on previous tomographic studies.The high velocity anomaly was interpreted as the slab remnants of the ancient Tethys subduction.We thus speculate that the observed scatterers are either related or induced by the subducted slab.展开更多
基金supported by the National Natural Science Foundation of China (Grant No.40574024)the Basic R&D Fund of Institute of Earthquake Prediction,China Earthquake Administration (Grant No.2009A19)
文摘Clear PKIKP precursors were observed from the Lanzhou CTBTO seismic array.We measured their incident angles,arriving azimuths and differential travel times with respect to the PKIKP arrivals using array analysis techniques.These measurements allowed us to locate the scatterers that generated the observed precursors.We found that the scatterers are located in the lowermost mantle beneath eastern Tibet,which is featured by a high-velocity anomaly based on previous tomographic studies.The high velocity anomaly was interpreted as the slab remnants of the ancient Tethys subduction.We thus speculate that the observed scatterers are either related or induced by the subducted slab.
