Math in the News: Issue 54

The Indonesian Earthquake

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

The Indonesian Earthquake

This map shows the location of the epicenter relative to population density.

The Indonesian Earthquake

This map shows the epicenter of the 2004 earthquake.

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.

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

Mag

nit

ud

e

Comparison of Two Indonesian Earthquakes

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

Inte

ns

ity

Comparison of Two Indonesian Earthquakes

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.

The Indonesian Earthquake

We can express the intensity of each earthquake using these expressions.

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.