Earlier quoted context omitted.
The Richter scale is exponential. According to chrisra a 7.8 earthquake release almost 4x the energy of a 7.4 quake. I didn't run the numbers, but it seems plausible the difference would be that big. According to Wikipedia[1] a 7.5 quake releases 11 petajoules of energy, while a 7.8 quake release 32 petajoules. [1] http://en.wikipedia.org/wiki/Richter_magnitude_scale#Example...
This is something that's always bothered me. The Richter scale is not, for normal people like myself, a good earthquake magnitude indicator. I always have trouble grasping that 7.5 and 7.8 are so far apart in terms of severity since my mind is set to find a .3 difference negligible. I would like to have a metric measurement of earthquakes that would allow me to more quickly understand the scale and size of a quake. E…
I experienced this first hand here in Christchurch, NZ. We had a 7.1M quake and then a 6.3M aftershock 6 months later. Despite being almost an entire magnitude smaller the 6.3M aftershock was 10x more destructive. This was primarily because the epicenter of the 6.3M quake was 40km closer to the city and some unusually high verticle accelerations caused by the strike slip motion of the fault and the local geography.
http://en.wikipedia.org/wiki/2010_Canterbury_earthquake
http://en.wikipedia.org/wiki/2011_Christchurch_earthquake
The Mercalli Intensity Scale was developed to give a better indicator of the actual effect to people on the ground.