Complex sentence: The 1994 Northridge earthquake in California caused swimming pools to overflow across southern California, and the massive Good Friday Earthquake that hit Alaska in 1964 caused seiches in swimming pools as far away as Puerto Rico.
Split into simpler sentences: The 1994 Northridge earthquake in California caused swimming pools to overflow across southern California. The massive Good Friday Earthquake that hit Alaska in 1964 caused seiches in swimming pools as far away as Puerto Rico.