Complex sentence: This caused a megatsunami that reached a height of 330 ft (100 metres), and killed an estimated 15,000 people.Untill 2011 it was the worst volcanic related eruption in Japan.
Split into simpler sentences: This caused a megatsunami that reached a height of 330 ft (100 metres), and killed an estimated 15,000 people. Until 2011 it was the worst volcanic related eruption in Japan.