Complex sentence: An area of its east face of 67,400 m² was laser-scanned from a distance of 800 metres and revealed that over a twelve-month period the face had lost 536 m³ of rock.
Split into simpler sentences: An area of its east face of 67,400 m² was laser-scanned from a distance of 800 metres. This revealed that over a twelve--month period the face had lost 536 m³ of rock.