Complex sentence: The country experienced the largest tsunami runup height of any location outside of Sumatra, which occurred at Khao Lak and the areas of Takua Pa district that are facing the Andaman Sea.
Split into simpler sentences: The country experienced the largest tsunami runup height of any location outside of Sumatra. The largest tsunami in Thailand hit Khao Lak and the areas of Takua Pa district that are facing the Andaman Sea.