Complex sentence: Damage to property on the coastal areas of Malaita and Small Malaita was caused mainly by high winds and rough seas with the southern three-quarters of Malaita severely damaged by strong winds.
Split into simpler sentences: Damage to property on the coastal areas of Malaita and Small Malaita was caused mainly by high winds and rough seas. The southern three-quarters of Malaita were severely damaged by strong winds.