Frictional melting and thermal fracturing recorded in pelagic sedimentary rocks of the Jurassic accretionary complex, central Japan

Jurassic rocks reveal earthquake mechanisms

27 November 2021

Measurements of rocks laid down in the Jurassic period have revealed possible mechanisms that could contribute to the magnitude of earthquakes.

The earthquake that unleashed the devastating tsunami in northern Japan in March 2011 originated in a zone where one tectonic plate is sliding under another. Deep-sea drilling in such subduction zones has revealed much about slipping that occurs at the shallow portion of the interface between the two plates, but little is known about what happens deeper down.

Now, four researchers, all at the University of Tsukuba in Japan, have analysed sedimentary rocks in a subduction zone that existed in the Jurassic period but which are now exposed to the surface.

They found evidence for melting caused by friction and thermal fracturing in these rocks. These processes could potentially accelerate seismic slip and thus make earthquakes more devastating.

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References

1. Earth and Planetary Science Letters 554, 116638 (2021). doi: 10.1016/j.epsl.2020.116638