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Nepal earthquake, magnitude 7.3, strikes near Everest

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Re: Nepal earthquake, magnitude 7.3, strikes near Everest

#11
That could be quite bad, because vast majority of houses in the area of Namche Bazaar has been built without steel-and-concrete reinforcement - just stones and cement, due to lack of motorable roads in Sulukhumbu region to supply steel and other building materials.

Re: Nepal earthquake, magnitude 7.3, strikes near Everest

#12
post #5

A magnitude 7.8 earthquake is 2.511 times bigger than a magnitude 7.4 earthquake on a seismogram, but is 3.981 times stronger (energy release). via http://earthquake.usgs.gov/learn/topics/calculator.php

I did not quite understand "3.981 times stronger (energy release)", but god bless everyone.

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...

Re: Nepal earthquake, magnitude 7.3, strikes near Everest

#13
post #5

A magnitude 7.8 earthquake is 2.511 times bigger than a magnitude 7.4 earthquake on a seismogram, but is 3.981 times stronger (energy release). via http://earthquake.usgs.gov/learn/topics/calculator.php

I did not quite understand "3.981 times stronger (energy release)", but god bless everyone.

The Richter scale is logarithmic and therefore, a doubling of values is not equivalent to a doubling of force.

Re: Nepal earthquake, magnitude 7.3, strikes near Everest

#15
post #12

Earlier quoted context omitted.

I did not quite understand "3.981 times stronger (energy release)", but god bless everyone.

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.

Edit: The difference between a 8.6 one and a 8.7 one is huge. The difference is as big as the difference between 0.0 and 8.35, in megatons at least.

Re: Nepal earthquake, magnitude 7.3, strikes near Everest

#16

Please help the OSM HOT [1] team to map the regions struck by the earthquake. Without proper/up-to-date maps, coordinating emergency efforts is hardly possible. [1] http://wiki.openstreetmap.org/wiki/2015_Nepal_earthquake

Please get used to how OSM works before starting to map. There has been lots of bad data added by new people to OSM in Nepal recently. Cleaning up may be more work than adding new.

Re: Nepal earthquake, magnitude 7.3, strikes near Everest

#18
post #5

A magnitude 7.8 earthquake is 2.511 times bigger than a magnitude 7.4 earthquake on a seismogram, but is 3.981 times stronger (energy release). via http://earthquake.usgs.gov/learn/topics/calculator.php

Which doesn't account for the fact that this one is shallower than the previous earthquake. Shallower earthquakes create considerably more damage.

Re: Nepal earthquake, magnitude 7.3, strikes near Everest

#19
post #15
post #12

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…

Using Charles Richter's formula

Magnitude of Earthquake M = log I / S

(where I is the intensity of the earthquake taken 100km from epicenter, S is the intensity of a standard earthquake)

First earthquake 7.8 = log I1 / S

Second earthquake 7.1 = log I2 / S

If we solve this for I1/I2, we get 10 ^ 1.10 ~ 12.5

> The intensity of first earthquake was 12.5 times as intense as the later earthquake.

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