Syvänjäristykset

Syvänjäristykset refer to earthquakes that originate at depths greater than 300 kilometers beneath the Earth's surface. These deep-focus earthquakes are distinct from shallow and intermediate-depth earthquakes, which occur at shallower levels. The majority of syvänjäristykset are associated with subduction zones, where one tectonic plate slides beneath another. As the subducting plate descends into the Earth's mantle, it experiences increasing pressure and temperature.

The exact mechanisms by which rocks can fracture and generate seismic waves at such extreme depths and temperatures are still a subject of scientific research. Unlike shallower earthquakes where brittle fracture is well-understood, the conditions in the mantle are thought to favor more ductile deformation. However, certain mineral phase transformations or the presence of fluids may play a role in enabling brittle failure at these depths.

Syvänjäristykset are typically felt less intensely at the surface compared to earthquakes of similar magnitude originating at shallower depths. This is because the seismic waves travel a greater distance and are attenuated more significantly through the Earth's mantle before reaching the surface. Despite their reduced surface impact, the study of syvänjäristykset provides valuable insights into the physical properties and processes occurring deep within the Earth's interior, particularly in subduction zone environments. They contribute to our understanding of plate tectonics and mantle dynamics.