I Felt by very few people; barely noticeable. II Felt by a few people, especially on upper floors. III Noticeable indoors, especially on upper floors, but may not be recognized as an earthquake. IV ...

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.

Scientists measure both the energy released in an earthquake and its damage. In 1902, Italian scientist Giuseppe Mercalli introduced a scale that measures the intensity of an earthquake based on its ...