The double-array (event- and receiver-array) stacking is applied to the P-wave data from 6 Fiji Is. events recorded by a local network of short-period seismographs in Japan to investigate VP structure in the lowermost mantle. A signal which may be interpreted as the reflection from a discontinuity at 170 km above the CMB (core-mantle boundary) is observed between P and PcP in the stacked record. As compared with the receiver-array stacking with a small number of stations applied to a single event, the double-array stacking is effective to detect the weak signal of PdP. ¿ American Geophysical Union 1996