Complex sentence: In May 1980, a strong earthquake swarm that included four Richter magnitude 6 earthquakes struck the southern margin of Long Valley Caldera associated with a, dome-shaped uplift of the caldera floor.
Split into simpler sentences: In May 1980, a strong earthquake swarm that included four Richter magnitude 6 earthquakes struck the southern margin of the Long Valley Caldera. It was associated with a, dome-shaped uplift of the caldera floor.