We know from the Incident, that the statue was intact when the black Rock came to the island around 1845. It can also reasonable be assumed that the statue was not present when the Dharma Initiative came to the island is the 1970s. In the last time flash, before locke turned the wheel, the statue was also intact. This was before the Orchid station was built and before the well was dug, as seen in LaFluer. When Locke turned the wheel, the "left behinders" stated that that flash was different, the ground shook like an earthquake. As afr as we know, the wheel was buried in a cavern to which there was no access to from above ground. It is my theory that this flash caused by Locke turning the wheel & effects on the island were the cause for the statue's collapse. It fits the timeline and could have been the catastrophic event that it would take to bring down such a large structure. Also, Locke was encourag! ed to turn the wheel by Jacob's adversary in the form of Christian Shepherd. This event satrted the pieces in motion that would provide for his loophole to kill Jacob. Symbollically, this coincides with the destruction of the statue, which also serves as Jacob's home. The fact that it occurred during the flash may also account for why there are no remains left on the island of the collapsed statue, as the remains were not moved when the wheel was turned.