Complex sentence: Early on May 18, an earthquake measuring 5.1 on the Richter scale struck the region, creating a massive landslide-of rock that released pressure on the volcano's crater, causing an ejection of steam.
Split into simpler sentences: Early on May 18, an earthquake measuring 5.1 on the Richter scale struck the region, creating a massive landslide-of rock. Pressure on the volcano's crater was released, causing an ejection of steam.