1. Earthquake magnitudes in Oklahoma
It is obvious that earthquake frequency has risen massively as wastewater injection became more prevalent. But what about the *magnitudes* of the earthquakes? Maybe Oklahoma is just getting a lot of tiny earthquakes, and there is not much cause for concern.
2. Seismicity around Mt. St. Helens
We can again learn from an analysis of Mt. St. Helens, shown here during its eruption in the fall of 2004.
Because Mt. St. Helens is an active volcano, the region has sensitive seismological sensing equipment, so the completeness threshold is very low, around 1.0.
3. ECDF of Mt. St. Helens earthquakes
Looking at ECDFs of magnitudes, the difference is striking between the quiescent period from 1990 to 2003 and the time around the 2004 eruption. There many more small earthquakes during the eruption.
We also see a departure from the Gutenberg-Richter Law during the eruption, so the *b*-value does not make sense to compute here.
But clearly, there is a major difference in the magnitudes of earthquakes around Mt. St. Helens when there is different geological activity.
4. Magnitudes in Oklahoma
In the next exercises, you will study magnitudes of earthquakes pre- and post- fracking in Oklahoma. First, you will verify that the Gutenberg-Richter Law actually does hold. You will then make estimates of the *b*-value before and after 2010, when wastewater injection became widespread. Finally, you will perform a hypothesis test to investigate differences in seismicity.
This is your final run-through of the EDA, parameter estimation, hypothesis test pipeline.
5. Let's practice!
I'll see you on the other side!