Complex sentence: The Galveston hurricane of 1900 subsequently devastated that city, killing approximately 8,000 people (possibly as many as 12,000), making it the deadliest natural disaster in U.S. history.
Split into simpler sentences: The Galveston hurricane of 1900 subsequently devastated that city, killing about 8,000 people or possibly as many as 12,000. This makes it the deadliest natural disaster in U.S. history.