In this issue of Math in the News we look at the recent earthquake near Indonesia and compare it to the devastating earthquake of 2004.

2. The Indonesian Earthquake
This map shows the location of the earthquake, which is near Indonesia.
(Source for all map graphics: http://www.usgs.gov.)

3. The Indonesian Earthquake
This map shows the location of the epicenter relative to population density.

4. The Indonesian Earthquake
This map shows the epicenter of the 2004 earthquake.

5. The Indonesian Earthquake
A side-by-side comparison of the two epicenters shows that the 2004
earthquake was closer to land. Because it was a much stronger earthquake,
its proximity also meant the potential for more damage. Note that both
earthquakes occurred under water, which is what causes tsunamis.

6. The Indonesian Earthquake
This graph compares the magnitude of the two earthquakes. The close
numerical values of the two magnitudes (8.6 vs. 9.1) suggests comparably
strong earthquakes. But magnitude uses a logarithmic scale.
0
1
2
3
4
5
6
7
8
9
10
2012 2004
Magnitude
Comparison of Two Indonesian Earthquakes

7. The Indonesian Earthquake
This graph compares the intensity of each of earthquake. Here you can
see the dramatic difference in intensity.
0.00E+00
2.00E+08
4.00E+08
6.00E+08
8.00E+08
1.00E+09
1.20E+09
1.40E+09
2012 2004
Intensity
Comparison of Two Indonesian Earthquakes

8. The Indonesian Earthquake
The intensity of an earthquake is proportional to an exponential expression
of base 10 whose exponent is the size of the earthquake magnitude. For
simplicity, let’s assume this proportion is an equation.

9. The Indonesian Earthquake
We can express the intensity of each earthquake using these expressions.

10. The Indonesian Earthquake
To see how much more intense the 2004 earthquake was calculate the
ratio of the two terms. You can see that the 2004 earthquake was three
times more intense.