Measuring earthquakes

Seismographs and Seismograms 

Seismographs record the extent of shaking by a pen identifying the trace of the movement on a rotating drum. 
The line graph produced is called a seismogram. 

The Mercalli and the Richter Scales 

Mercalli 

• Measures the effects caused by earthquakes
• Measured by different people's observations 
• Quantified by observation of effect on earth's surface, human objects and man made structures
• The Scale is from I (not felt) to XII (total destruction)
• Varies depending on distance from epicentre 

Richter

• Measures the energy released by the earthquake 
• Measured using a Seismograph
• Calculated by s Base 10 logarithmic scale obtained by calculating the logarithm of the amplitude of waves
• Varies at different distances from the epicentre, but one value is given for the earthquake as a whole. 
• The scale is from 2.0 to 10.0+ (never recorded). 
• A 3.0 is 10 times stronger than a 2.0 earthquake 

Richer scale: A scale measuring from 0 to 10 used for measuring earthquakes, based on scientific recordings of the amount of movement. 

Mercalli: A means of measuring earthquakes by describing and comparing the damage done, on a scale of I to XII.