High volume trade day

The day started with 1.6million shares on the buy side and 1million shares on the sell side.

For most of the day, there was little trade executed. Mid afternoon the picture began to change with sellers and buyers being almost equal and the share price declining to 20 cents.

At 4pm, the picture dramatically changed with 8 million shares wanting to buy and 2 million selling with an indicative price of 25 cents. Then the volume on the buy and sell side increased with, at the close some 16million shares on the sell side and 15 million on the buy side with a final 10 minute turnover of almost 12 million shares trading at 21 cents.

Where did this volume come from: on the buy side (pent-up demand?) and on the sell side (shorters?). Why this rush to trade? Is anything significant about to happen (eg. ASX announcement re: finance agreement for Philippines power plant?)

I would appreciate if anybody can shed light on what happened late afternoon and especially between 4pm and 4.10pm.