Selecting 263 substorm events with Pi 2 pulsation, we have statistically-investigated temporal variations in the total pressure and the electric field (E=-V¿B) in the near-Earth magnetotail with GEOTAIL data. It was found that a total pressure decrease occurs first in the premidnight region around (X,Y)~(-18,7)RE in the GSM coordinates about 1 or 2 min before onset, and propagates to the surrounding regions successively. The dawn-to-dusk electric fields around X~-10 RE and X~-28 RE have the same magnitudes and develop considerably about 1 min after onset, while that around (X,Y)~(-20,5)RE is smaller. These results strongly suggest that the magnetic reconnection takes place at least 2 min earlier than the dipolarization, and that, on the average, the center of the energy release is initially located around the premidnight region of (X,Y)~(-19,6)RE. ¿ 1999 American Geophysical Union