Earthquakes and seismic activity often happen with sudden movements underground with tectonic plates. Seismographs are used by scientists to measure the time, location and strength of an earthquake.

We know an earthquake is severe when it has a high magnitude number. The 1985 quake that devastated Mexico City was an 8. The quake that shook central Mexico this week was a 7.1. But what exactly is ...

Tropical systems tracked by the National Hurricane Center will be classified as depressions, tropical storms and hurricanes based on their intensity. The NHC will label a system a tropical depression ...