Complex sentence: The 1861 Sumatra earthquake occurred on February 16 and was the last in a sequences of earthquakes that ruptured adjacent parts of the Sumatran segment of the Sunda megathrust.
Split into simpler sentences: The 1861 Sumatra earthquake occurred on February 16,1861. It was the last in a sequences of earthquakes that ruptured adjacent parts of the Sumatran segment of the Sunda megathrust.