A new study sheds light on regions where earthquake activity is less likely to occur.
Researchers from Cardiff University in Wales and Tsukuba University in Japan studied a specific tectonic process on the oceanic boundaries between tectonic plates and managed to identify a sliding mechanism that generates significantly less seismic shocks.
The earth's crust is not a continuum medium but is composed of several parts known as tectonic plates that lie over its mantle. Tectonic plates are not immobile but move with respect to each other. Depending on the kind of movement between two adjacent plates, 3 types of boundaries are created:
The movement of the tectonic plates generates high stresses along their boundaries. In a convergent boundary, the build-up stress is alleviated either by sudden slips that release large amounts of energy and produce earthquakes or by a slow and steady creep movement between the two plates. What exactly happens in plate boundaries is an issue not fully understood yet.
The aforementioned study, published in Science Advances, suggests that, in a convergent boundary along the ocean floor, under certain circumstances, tectonic plates tend to behave more in a creeping manner, producing far less seismic shocks than previously considered. What leads to this behavior is that cracks on the oceanic floor along the plate boundary fill with water and, as a result, weak minerals are produced. Those minerals facilitate the creeping movement between the 2 plates.
The research team utilized modern imaging techniques to study the microscopic structure of rocks that used to be located within an oceanic subduction zone in the past but are now found on the ground surface (as a result of geologic processes). They managed to calculate the stress that the plate boundary was subjected to, and concluded that the material was weaker than anticipated. “Our study therefore confirms that oceanic crust, typically thought to be strong and prone to deforming by earthquakes, may instead commonly deform by creep, providing it is sufficiently hydrated,” Christopher Tulley, lead author of the study and a researcher at Cardiff University, stated.
The aim of the study is to shed light on regions that are less prone to earthquakes due to the aforementioned mechanism and to further study the complex behavior of oceanic plate boundaries. An ambitious future objective of seismology is the accurate prediction of seismic shocks and this study is providing significant insights towards this goal.
Source: Cardiff University
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