How to distinguish an earthquake from aftershock?

While the new House of Representatives is still busy debating the extraction of gas in Groningen, scientists are also busy. For a long time it was not clear whether the aftershocks occurred in Groningen or whether the earthquakes were caused directly by gas extraction.

The more you know about the cause of tremors, the better in the future you can predict which conditions will cause tremors, their severity, and the amount of time that will elapse between shocks. For example, you can also decide if it makes sense to wait a while for repairs, or if it’s important to get started very quickly.

To see if there were aftershocks in Groningen – which behave very differently from the initial earthquakes – the researchers put the data into a statistical model that made it possible to calculate the type of earthquake that occurred. It turns out that about 27 percent of cases were aftershocks.

Well, that doesn’t answer all questions yet. The researchers also like to look at what a maximum earthquake is and what are the major modifications in gas extraction that will affect earthquakes. Models looking at soil movement will also be included for this. So a little math and a little physics.

In this sound you can hear researcher Edwin van den Heuvel from Eindhoven University of Technology. Read more about research here: The statistical model shows: earthquakes in Groningen are partly aftershocks. You can find the paper here: Intermittent time distribution and frequency of aftershocks in unstable induced earthquakes.