GEOG 1350 Lecture Notes - Lecture 2: Mercalli Intensity Scale, San Andreas Fault, Richter Magnitude Scale

• School: University of Guelph
• Department: Geography
• Course: GEOG 1350
• Professor: Mark Moscicki

Document Summary

They result from the rupture of rocks along a fault. Energy from an earthquake is released in the form of seismic waves. They are mapped according to the epicentre; the focus is located directly below the epicentre. They are measured by seismographs and compared by magnitude. The magnitude of an earthquake is expressed as a number to one decimal place. This type of measurement was first developed by richter in 1935. The richter scale measured the strength of a wave at a distance of 100 km from the epicentre. More accurate methods have been developed and the richter scale is no longer used. Today, earthquakes are measured using the moment magnitude scale (m) The scale is determined by: the area that ruptured along a fault plane the amount of movement or slippage along the fault the rigidity of the rocks near the focus (elasticity of the crust) Similar to the richter scale, it is a logarithmic scale (quantitative)