Complex sentence: The company denied any problems relating to their structure and design of the dam, and believed that the cause of the crack and inevitably the collapse involved a landslide or landslip, a landslip being a geographical movement of land that usually results in the ground becoming unstable.
Split into simpler sentences: The company denied any problems relating to their structure and design of the dam, and believed that the cause of the crack and inevitably the collapse involved a landslide or landslip. A landslip being a geographical movement of land that usually results in the ground becoming unstable.