An earthquake happens near a city and levels many of the older buildings downtown. In a city 40 minutes away, the same earthquake only causes windows to rattle. What magnitudes will these cities report for the earthquake?

1 Answer
Oct 17, 2017

only intensity changes with distance, not the actual magnitude

Explanation:

intensity and magnitude of an earthquake are to very different things
firstly intensity is the amount of damage the earthquake causes in an area. it depends upon many factors including infrastructure and stability of the ground in that area. intensity has its own scale known as mercalli intensity scale which tell us about the effect of earthquake in that area (which is not told as a number on the news, just as how much damage has it caused.

secondly and more importantly, magnitude is calculated by meteorological departments of city or a country by seismograms. Magnitude is calculated by seeing the 1) difference of P and S waves, 2) distance of focus of earthquake from seismogram station and 3) amplitude of the wave on seismogram.
Magnitude is recorded on scale known as ritcher scale (which is told as a number on news)