>Mysterious waves continue? Underground bunker mapping tech?
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Thinking about the mysterious 17 second interval seismic waves that went round the world.
(Natl Geo - Article excerpt)
However, there was no big earthquake kicking off the recent slow waves.
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Compare report of these mysterious 'slow' waves going around the world → to the description in this scientific paper ref: (Low Frequency Seismic Waves effectiveness at mapping underground reservoirs)
(MAY 2006 - THE LEADING EDGE)
(Reservoir imaging using low frequencies of seismic reflections.)
GENNADY GOLOSHUBIN and CONNIE VANSCHUYVER, University of Houston, Texas, USA
VALERI KORNEEV, Lawrence Berkeley National Laboratory, California, USA
DMITRY SILIN, University of California at Berkeley, USA
VJACHESLAV VINGALOV, West-Siberian Research Institute of Geology and Geophysics, Tyumen, Russia
There are numerous laboratory and field examples in which low-frequency components of reflected seismic waves show surprising imaging capabilities. Ironically, such components are often fil- tered out as useless in conventional data processing. However, as we demonstrate below, this part of the signal contains the most important information about the reservoir.
Let us consider three examples of field data processing. In all of them, the hydrocarbon-rich zones of the reservoir were localized using low-frequency analysis. These zones were confirmed on the basis of experience with well-pro- duction data. The imaging analysis was performed without well data. Note that conventional methods of data processing could not detect the hydrocarbon zones.
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Low frequency seismic waves → use for underground mapping been studied for some time now.
https://www2.lbl.gov/TT/publications/1663pub11.pdf
https://www.nationalgeographic.com/science/2018/11/strange-earthquake-waves-rippled-around-world-earth-geology/