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Precursory Stress Changes Before Large Earthquakes

For more than a century, scientists wondered what happens before large earthquakes. Are there any precursors? Finally, we have an answer to this question.

Recently, the Quantectum team published a new article in the Journal of Structural Geology entitled "Precursory stress changes before large earthquakes; on a new physical law for earthquakes".

You can access the article published by ElseVier here.

In this article, we discover a new and previously unknown physical law for earthquakes, which defines the maximum possible magnitude Mmax of an earthquake and the value of the normalized tectonic shear stress field tau (or normalized driving stress) in tectonic zones on Earth. This law describes a logarithmic dependence of M on tau of the form Mmax = M0 + K log (tau), and is called the maximum magnitude law (MM-law). The parameters M0 and K depend on time and place. The most important consequence of this law is, however, that the largest M7.5+ or even M8+ earthquakes only occur in the highest/strongest normalized tectonic shear stress fields, which change rapidly over time. Two scenarios are observed. In the first scenario, the normalized shear stress was already high (long) before the actual earthquake. In the second scenario, the normalized shear stress was initially moderate but began to increase several months before the actual earthquake. In this article, we discovered and described an important new earthquake precursor – the normalized tectonic shear stress. There is an increased probability of very large earthquakes in those regions, where the normalized shear stress increases significantly. These changes are precursory. They occur months before the large earthquakes. This means they can be used as a tool in the development of advanced time-dependent PSHA models.

2_Global_shear_stress_field
Picture 1: Global shear stress field

 

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