The earth is made of overlapping plates that can shift and cause earthquakes.
The science of measuring earthquakes has evolved over the last few thousand years. According to the monitoring time line presented by the United States Geological Survey, the earliest monitoring began in 373 B.C. For most of recorded history, earthquakes have been measured according to observable intensity. Now they are measured through mathematical formulas on magnitude, fault geometry and seismic movement, energy, intensity and depth determination. This calibrated system results in more accurate measurements.
Richter Scale
Created by seismologist Charles Richter in 1934, the Richter Scale is used today to measure the magnitude of an earthquake. The Richter Scale has developed into incorporating several scientific factors such as the energy released by an earthquake and depth. This is the scientific scale, while the observable effects are measured by the Modified Mercalli Intensity Scale.
Modified Mercalli Intensity Scale
Developed by Guiseppe Mercalli in 1902, the Mercalli is a 12-point scale based on intensity. This scale was modified in 1931 by American seismologists Harry Wood and Frank Neumann into what is currently in use today. The MM Intensity Scale does not have a mathematical base, but is scaled on volatile observations of damage and felt effects. Roman numerals are used to rank the MM Intensity Scale.
European Macroseismic Scale
European countries use the European Macroseismic Scale, or EMS-98. This scale originated in 1988, was modified in 1998 and is based on intensity. Instead of measuring the energy released in an earthquake like the Richter Scale, the EMS-98 notes how an area is affected by an earthquake's intensity.
Tags: Intensity Scale, Richter Scale, based intensity, energy released, energy released earthquake
