Research shows that improved early-detection warning systems and artificial acoustic-gravity waves could help to stop a tsunami

 

Tsunami_Evacuation_Route

In the
last two decades, tsunamis have been responsible for the loss of almost half of
a million lives, millions of dollars in property destruction, and profound
environmental effects. Such a forceful act of nature may seem like something
beyond our control, but Dr. Usama Kadri of Cardiff University’s School of
Mathematics believes that it is possible to mitigate the most severe aspects of
a tsunami by combating the waves with artificial acoustic-gravity
waves
(AGW).

Tsunamis
are produced by seismic events, such as an underwater earthquake, landslide, or
volcanic eruption, which trigger a series of waves that can travel the length
of an ocean at speeds of up to 500 mph. The destructive impact on shore is
determined by the wavelength and amplitude of the tsunami. Today’s Tsunami
Warning Systems

use seismological and tidal warning stations that watch for potential
earthquakes at sea that could cause a tsunami. The rudimentary warning system
gives local residents only minutes to prepare. Previously, Kadri proposed a
better system based on AGWs.

In
addition to surface waves, tsunamis also generate acoustic-gravity waves, sound
waves that propagate in water with amplitudes compressed by gravity. AGWs form
with tsunamis and induce pressure disturbances in the entire water column. The measurable
pressure signatures marked on the sea floor serve as excellent tsunami
precursors and allowing scientists to identify the epicenter location. By
installing detection stations deep in the ocean, where AGWs are expected to
travel freely in the water column, scientists will be better able to predict
the time and force of tsunamis while they are still far out at sea.

What’s
more, tsunamis may no longer be an absolute impending danger; Kadri also believes
that it is feasible for artificial AGWs to interact with surface-gravity
(tsunami) waves and redistribute the total energy of a tsunami wave over a
larger space. The theory is based on a three-wave interaction mechanism known
as a resonant triad. The triad interaction would be comprised of a single long
surface ocean wave, representing the tsunami, and two AGWs. Once a tsunami is
identified using the early detection warning system, Kadri’s idea would be to
pulsate two finely tuned high-frequency trains of AGWs at incoming tsunamis and
disrupt their waveforms to reduce their amplitude. The subsequent wave
dispersion would make a tsunami much less powerful and cause much less damage.

Mitigation_System

Schematic
illustration of the proposed mitigation system in which two AGWs are
transmitted toward the tsunami to form a resonant triad

The
usability of a counter-tsunami system is predicated on the development of a
deep-ocean detector network to track and analyze the pressure signatures of
tsunamis on the sea floor to allow proper anti-tsunami pulses to be configured
to diminish the amplitude of the wave. To generate such AGWs would require
sonic transducers large enough to handle the force equivalent to a nuclear
warhead.

“In
practice, generating the appropriate acoustic-gravity waves introduces serious
challenges due to the high energy required for an effective interaction with a
tsunami,” says Kadri. Despite the challenges, Kadri’s research shows the
potential that AGWs could have in diminishing the disastrous effects of
tsunamis.

Sources:
Heliyon, News
Atlas
, National
Geographic