How does the intensity of an earthquake change with distance from the epicenter?

Question

With reference to the Richter scale of course.

Does the intensity diminish linearly, or is it logarithmic? If so, how many Richter scale measures does it change as you move away, say, 10 kilometres?

Answer 1

Measuring earthquake intensity is a complicated subject.However to make you under stand I am simplifying the concept. If you sense the earthquake wave from a distance of 100 k/m the maximum shaking will be 0.1 mm.This will increase by ten fold for each Richter scale. The shaking will be reduced by inverse square of the distance. It is the function of inverse square. But the force released will increase by 31.7 times more for each Richter scale. According to the geological condition the affecting place may be near or far away from epicenter.If the force is released near epicenter the damage will be more and if the force is released away from epicenter the damage will be less.There are some other factors like amplification factor and liqification that also have to be considered for the amount of destruction's. Please refer the chart for energy release.You can also visit A.Ganapathy India in google site to see various answer connected with earth science.

Approximate TNT (Tri nitro telecom )  Yield for Seismic Energy                    

                       Richter scale

                                   1                     30 lbs  

                                   2. 1 ton

     3. 29 ton

     4. 1000 ton

     5. 32000 ton

     6. 1 million ton

     7. 32 million ton

     8. 1 billion ton

     9. 32 billion ton

    10 1 trillion ton.

Answer 2

Well, the Richter Scale is based on logarithmic proportions, so I would deduce that one mile away from the epicenter, the magnitude would be 1/10 less. (Or however much less - math is not really my strong suit.)

Answer 3

The epicenter is the point on the surface above the location where the fault begins the slip which generates the earthquake. There is a common myth that most damage will occur near the epicenter of the earthquake, or that the epicenter is synonymous with "ground zero." However, the earthquake epicenter is typically not the point at which most damage occurs. The fault rupture can be tens of miles long and waves are generated along the entire length of the fault.

Predictions of ground shaking intensities are not based on distances from possible epicenters, but on distances from known faults, or segments of faults, on which large earthquakes are anticipated.

Intensity decreases ("attenuates") with distance from the fault.  The critical distance is not simply the nearest distance to the fault. Seismologists have come to realize that earthquake sources radiate energy at depth; thus, the distance used to attenuate expected shaking must be measured between the site and this underground source.

For more info, go to:

http://www.abag.ca.gov/bayarea/eqmaps/do...