While that many not have been pleasant for those that were affected, Kiwamu Nishida, with the Earthquake Research Institute at the University of Tokyo, and Ryota Takagi, with the Research Center for Prediction of Earthquakes and Volcanic Eruptions at Tohoku University, were afforded the opportunity to detect both P- and S-wave microseisms.
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The findings, which have appeared in the journal Science, could herald a new way of studying the globe’s hidden depths.
Dr Bromirski from the University of California San Diego, said: “Most of what we know about the internal structure of the Earth has been determined from studying the way natural disaster waves propagate, through the lower crust and the mantle and the core”.
It’s the first time scientists have observed this particular type of tremor on the sea floor, known as an S wave microseism.
The faint and deep tremors “weather bombs” can cause in the oceanic crust run through the earth and can be detected in places as far away from the Atlantic as Japan.
“This is the first time that scientists were able to observe the S wave of a micro-earthquake”, the study continues.
In an accompanying commentary on the Japanese research, Peter Gerstoft and Peter Bromirski of the University of California, San Diego said that studying microseismic S waves may “add to our understanding of the deeper crust and upper mantle structure”, and “give seismologists a new tool with which to study Earth’s deeper structure”.
Essentially the waves from the “weather bomb” were big enough that there was enough energy left that the wave from the surface became a wave striking the ocean floor creating these microseisms, that resemble very weak earthquakes.
The two main types of seismic waves are surface and body waves. They are harder to detect, and until now, an S wave had never been traced to its source before. In southern Japan’s Chugoku region, they used a vast network of 202 stations.
Tracking these elusive, faint tremors could help geoscientists map the different materials that make up the Earth’s interior because tremors change direction depending on the type of material they pass through. Because of this, vibrations were absorbed by the seabed and tremors were felt even in Japan – the opposite side of the North Atlantic.
According to New Scientist, Nishida referred to the use of such a large number of seismographs to detect the S-waves as important in detecting station density.
A weather bomb is an intense low pressure system where dry air from the stratosphere flows into an area of low pressure. And for the first time they detected these deep-earth tremors known as secondary seismic wave name (S).
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The scientists were of the view that the microseisms have provided an insight into the planet’s deep structure.
