Complex sentence: The Indo-Australian Plate and Antarctic Plate Boundary is an active divergent boundary known as the Southeast Indian Ridge (SEIR), which ranges approximately 2000 kilometers at the bottom of the southern region of the Indian Ocean.
Split into simpler sentences: The Indo-Australian Plate and Antarctic Plate Boundary is an active divergent boundary known as the Southeast Indian Ridge (SEIR). The SEIR ranges approximately 2000 kilometers across the southern region of the Indian Ocean.