The detonation of Jughead's core caused the destruction of the statue. The blast may also be what submerged The Island in the alternate timeline.
The rest of the statue was destroyed due to a prior system failure. The statue may have been created with metallic elements, or constructed over a metal frame. The missing pieces may have been sucked inland or propelled out to sea by a previous system failure or discharge from the magnetic anomaly in the Swan.
- The Swan wasn't built until 1977, by the 1974 flashback while Locke attempted to spin the frozen wheel the statue had been demolished, as it was no longer visible.
A volcano that erupted a long time ago is mentioned in the episode "The Man Behind The Curtain" which is a Ben flashback. The volcano might have been responsible or partly involved for the destruction of the statue.
The same tsunami that beached the Black Rock helped topple the statue. The Black Rock crashed into the statue and made it look deformed.
The volcanic eruption on the island was caused by an earthquake that also destroyed the statue. The earthquake could have been natural or due to the wheel turning, which induced an earth-shaking effect.
The eruption of Krakatoa in 1883 caused massive tsunamis throughout the South Pacific, and that could also have grounded the Black Rock.
The statue simply crumbled due to the elements and the force of gravity over a long period of time.
- Given the obvious Egyptian inspiration, and considering the fortitude of structures such as the pyramids at Giza or the Valley of the Pharaohs, this is rather unlikely.
- The weather and climate differs in the island from Egypt. The fact that the statue is by water could cause it to eventually decay over time.
Locke Turning the Wheel
Something from turning the wheel caused the statue to fall. After Locke turned the wheel, Miles commented that the time-shift was different, that it felt more like an earthquake. This "earthquake" was the vibration caused by the statue falling. ("LaFleur")
- The statue must have fallen in ancient times, or else there would be more debris in modern times remaining.
- Except that the statue was still standing during the conversation between Jacob and his enemy. Unless the ship off the coast had traveled through time it definitely is not "ancient". Considering the ship was probably the Black Rock the statue was standing at least until the 1800s.
Statue Stance Theory
It is very obvious that the stance from when the statue is first seen in it's entirety (while the losties were skipping) that is difference from when we see the statue on the beach with Jacob and Nemesis. In one scene, it is standing with legs slightly apart, with the right leg almost more in front than the left. This is also how the statue appears on the tapestry.
When the beach scene is shown, the legs are straight together. This may signify that somehow the time was altered there as well OR the Losties are also traveling between timelines when they start skipping.
- Or maybe the statue was alive prior to its destruction (a type of robot or something) and changed the stance by itself.
- Nothing of the like has been introduced in the Lost story, it would be jumping the (dharma) shark to introduce a giant mechanical Taweret into the show at this point. Subtlety seems to be very key in this entire story, and that would be a little less than subtle.
- The statue's legs are NOT straight together in the beach scene. That is just a trick of the camera's perspective. You can see by looking at it that the left foot is ahead of the right foot (just like on the tapestry). If there are any further doubts, you need only look at the model used for the CGI. The fact that the cloth pattern and leg positions seem to be opposite when the beach scene is compared to the time-skipping scene can most likely be explained by a reversal of the camera shot (which happens more often than you think, as a way to better frame a shot)... not by anything as dramatic as multiple statues or (heaven forbid) a sentient walking statue.
- The statues legs ARE straight in the beach scene. In the LaFleur episode, we see from upper-leg up and it looks like the right leg is in front. The Tapestry depiction of the Statue shows the Left Leg forward...Is this tapestry a clue from Jacob that the Left/MIB is ahead and out of balance? As one of the characters once said, "Are you on the same Island that I am" it is possible the subtle difference explains who is in power.
- Notice also that the right foot "Jacob side" is the one left standing.
MIB/Jacob Destroyed it on Purpose
Given that Taweret is the Egyptian Goddess of childbirth and fertility, either Jacob or the MIB destroyed it to prevent anyone coming to the island having children. This would both prevent them settling long term, and also having offspring which either Jacob or the MIB could use against the other. In his smoke form, the MIB is very powerful.
- There has to be a connection between the statue being demolished and the the extinction of child birth on the island.
- MiB persuaded one part of the Black Rock Crew to destroy it in an earlier attempt to kill Jacob (Jacob persuaded other part of the Black Rock Crew to build the Lighthouse?)
- Amy gave birth to Ethan in 1977 and she was fine, and by 1974 the statue was demolished.