What is a bad earthquake?

What is a bad earthquake? Scientists assign a magnitude rating to earthquakes based on the strength and duration of their seismic waves. A quake measuring 3 to 4.9 is considered minor or light; 5 to 6.9 is moderate to strong; 7 to 7.9 is major; and 8 or more is great.

Scientists assign a magnitude rating to earthquakes based on the strength and duration of their seismic waves. A quake measuring 3 to 4.9 is considered minor or light; 5 to 6.9 is moderate to strong; 7 to 7.9 is major; and 8 or more is great.