Earthquake 101 – Some Things You Need To Know

How are earthquakes recorded and measured?

USGS image
USGS image

According to USGS, earthquake scientists (seismologists) record waves using instruments called seismographs. The recording they make is called a seismogram. These recordings are used to help measure the size or magnitude of the quake.

Two scales are commonly used to measure earthquakes: the Mercalli Scale and the Richter Scale. The Mercalli Scale, the older of the two, measures the intensity of the earthquake – the impact or effect on people and property, observed over a limited geographical area. Intensity scales assign whole numbers usually from 1 to 12 to describe these observed levels of shaking. An intensity of 1 means the earthquake was not felt, while 12 means absolute and total destruction.

The Richter Scale measures the magnitude or amount of energy released by the earthquake. This is a measure of size for earthquakes based on the seismogram. It was developed by Charles Richter in 1935. He used the logarithmic scale (which scales numbers by a factor of 10) to accommodate the wide range of ground motions, which earthquakes can cause, and this has persisted to the present.