To start the sequence you must first use your ground pound ability on a circular platform at the open deck area. You will know if you have done this correctly as the platform will buckle and break.
The next thing you will need to do is destroy two power cores using any weapon, the first is located on the back rail and the second is located just ahead of it at the Yellow corner. Destroy the yellow corner core last.
After destroying the yellow corner core look slightly to the right and you will see a large mining vehicle be picked up, crushed and swallowed by the sandworm itself before retreating back under the sand.