Employees of the Department of physics of sea and land waters, faculty of physics, Moscow state University, together with colleagues from the Japan Agency for marine and terrestrial research and technology (JAMSTEC) and the University of Kagawa (Japan) was discovered and in details investigated the effect of generation of gravity waves in the ocean moving along the bottom surface seismic waves. The study is published in the journal of Geophysical Research.
Scientists of physical faculty of Moscow state University have discovered a new phenomenon — free gravitational waves in the ocean excited by seismic surface waves. Short name for the observed phenomenon, which would correctly reflect its physical essence, yet. In the article scientists propose the acronym “FGSS waves” (Free Gravity waves excited in the ocean by Seismic Surface waves — free waves in the ocean excited by seismic surface waves). “We consciously avoid the possible term “the harbinger of a tsunami”, as the presence or absence of FGSS waves does not allow us to judge the impending disaster (tsunami),” says the author, head of the Department of Geophysics, Professor of physics of sea and land waters of Moscow state University Mikhail Nosov.
However, minor sea level fluctuations on the shore, obliged FGSS waves, in principle, can serve as a natural alarm, warning of a tsunami. In addition, the seismic waves are the right kind of warning signal. In some cases, FGSS waves likely to have a significant amplitude and present danger to life and property. However, this question needs a special study.
“Based on the analysis of records obtained by a network of deep sea observatories DONET during a catastrophic earthquake and tsunami on March 11, 2011 off the coast of Japan (Fig.1), found that when passing along the bottom of the ocean waves love and Rayleigh waves in a water layer produce free gravitational waves, which were more than an hour ahead of the entry of the tsunami waves (Fig. 2),” says Professor Mikhail Nosov.
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