This fascinating talk poses the question: is the way science approaches
life’s biggest mysteries restricting our ability to solve them? Life
on this planet is the history of rule breakers – species that didn't
get the memo about how they were supposed to behave.
So if we are
studying rule breakers, then shouldn't how we study them break the
rules, too? Alejandro Sánchez Alvarado is a researcher at the
Stowers Institute for Medical Research and the Howard Hughes Medical
Institute and Fellow of the American Academy of Arts and Sciences. Dr.
Sánchez Alvarado's current research efforts are aimed at understanding
the molecular and cellular basis of animal regeneration.
Alejandro Sánchez Alvarado is an advocate for underwater creatures with
behaviors almost too weird to believe.
The sea is full of strange, little-understood creatures, says researcher
Alejandro Sánchez Alvarado at TEDxKC
(Collage: Alejandro Sánchez
Alvarado)
From a plankton/jellyfish that
reproduces asexually and births its slinky-like progeny from its “head”
(see below) to a worm that can be sliced into 18 pieces and keep living,
the researcher believes investigating these little-understood lifeforms
— and finding new ones — may hold the secret to new breakthroughs in
science.
A tunicate called Thalia democratica asexually births its offspring from its “head”
(Video: Alejandro Sánchez Alvarado)
We have only combed through a tiny section of the world’s oceans,
Alvarado says, while “ninety-five percent of our oceans remains
unexplored.”
This 95% could be the key to cures for currently incurable
diseases, better understanding of our genetic history, expansions to our
tree of life, if only people believed in the value of this exploration,
Alvarado says.
“We are measuring an astonishingly narrow sliver of life
and hoping that those numbers will save all our lives [by propelling
research],” he says.
“What is even more tragic is that [many underwater creatures']
biology remains sorely understudied,” Alvarado says. For example — the Schmidtea mediterranea, a type of flatworm that is common in coastal areas around the Mediterranean can regenerate itself after being chopped up into parts, yet it isn’t a household name or hot button topic in science.
“You can grab one of these animals and cut them into 18 different
fragments and each and every one of those fragments will go on to
regenerate a complete animal in under two weeks,” he says.
“18 heads, 18
bodies, 18 mysteries.”
The regeneration process of a Schmidtea mediterranea
“For the past decade and a half or so I’ve been trying to figure out how
these little dudes do what they do and how they pull this magic trick
off, but like all good magicians they’re not really releasing their
secrets,” Alvarado says.
More bizarre animals loved by Alejandro Sánchez Alvarado
A new NASA study (published in Journal of Geophysical Research -- Oceans) is challenging a long-held theory that tsunamis form
and acquire their energy mostly from vertical movement of the seafloor.
An undisputed fact was that most tsunamis result from a massive
shifting of the seafloor -- usually from the subduction, or sliding, of
one tectonic plate under another during an earthquake. Experiments
conducted in wave tanks in the 1970s demonstrated that vertical uplift
of the tank bottom could generate tsunami-like waves.
In the following
decade, Japanese scientists simulated horizontal seafloor displacements
in a wave tank and observed that the resulting energy was negligible.
This led to the current widely held view that vertical movement of the
seafloor is the primary factor in tsunami generation.
The animation shows how waves of energy from the Tohoku-Oki earthquake and tsunami of March 11, 2011, pierced through into Earth's upper atmosphere in the vicinity of Japan, disturbing the density of electrons in the ionosphere. These disturbances were monitored by tracking GPS signals between satellites and ground receivers. A model of ocean tsunami wavefronts [Song, 2007] is overlaid in blue to show the correlation between variations in the ionosphere above and ocean surface below.
Note that traveling ionospheric disturbances (TIDs), visible throughout the animation, are correlated with the position of the tsunami.
In 2007, Tony Song, an oceanographer at NASA’s Jet Propulsion
Laboratory in Pasadena, California, cast doubt on that theory after
analyzing the powerful 2004 Sumatra earthquake in the Indian Ocean.
Seismograph and GPS data showed that the vertical uplift of the seafloor
did not produce enough energy to create a tsunami that powerful.
But
formulations by Song and his colleagues showed that once energy from the
horizontal movement of the seafloor was factored in, all of the
tsunami’s energy was accounted for.
Those results matched tsunami data
collected from a trio of satellites –the NASA/Centre National d’Etudes
Spatiales (CNES) Jason, the U.S. Navy’s Geosat Follow-on and the
European Space Agency’s Environmental Satellite.
Further research by Song on the 2004 Sumatra earthquake, using
satellite data from the NASA/German Aerospace Center Gravity Recovery
and Climate Experiment (GRACE) mission, also backed up his claim that
the amount of energy created by the vertical uplift of the seafloor
alone was insufficient for a tsunami of that size.
“I had all this evidence that contradicted the conventional theory, but I needed more proof,” Song said.
Animation of ‘The Earth’ - modelling tsunami waves propagating over the globe.
With a resolution of 3km and a time step of 1 min, we brought together 10 previous tsunami events in 24 hours - in less than 5 hrs on 36 cores.
The model shows (in order of appearance and triggered every 2 hours): Solomon Islands 2007, Tohuku 2011, Sumatra 2004, Makran/Balochistan 1945, Greece 1956, Lisbon 1755, Dominican Republic 1946, Ecuador/Colombia 2016, then Tohuku 2011 and Valvidia 1960 (simultaneously) and Kamchatka 1952.
His search for more proof rested on physics -- namely, the fact that
horizontal seafloor movement creates kinetic energy, which is
proportional to the depth of the ocean and the speed of the seafloor's
movement.
After critically evaluating the wave tank experiments of the
1980s, Song found that the tanks used did not accurately represent
either of these two variables.
They were too shallow to reproduce the
actual ratio between ocean depth and seafloor movement that exists in a
tsunami, and the wall in the tank that simulated the horizontal seafloor
movement moved too slowly to replicate the actual speed at which a
tectonic plate moves during an earthquake.
“I began to consider that those two misrepresentations were
responsible for the long-accepted but misleading conclusion that
horizontal movement produces only a small amount of kinetic energy,”
Song said.
Building a Better Wave Tank
To put his theory to the test, Song and researchers from Oregon State
University in Corvallis simulated the 2004 Sumatra and 2011 Tohoku
earthquakes at the university’s Wave Research Laboratory by using both
directly measured and satellite observations as reference.
Like the
experiments of the 1980s, they mimicked horizontal land displacement in
two different tanks by moving a vertical wall in the tank against water,
but they used a piston-powered wave maker capable of generating faster
speeds.
They also better accounted for the ratio of how deep the water
is to the amount of horizontal displacement in actual tsunamis.
The new experiments illustrated that horizontal seafloor displacement
contributed more than half the energy that generated the 2004 and 2011
tsunamis.
“From this study, we’ve demonstrated that we need to look at not only
the vertical but also the horizontal movement of the seafloor to derive
the total energy transferred to the ocean and predict a tsunami,” said
Solomon Yim, a professor of civil and construction engineering at Oregon
State University and a co-author on the study.
Photo taken March 11, 2011, by Sadatsugu Tomizawa
and released via Jiji Press on March 21, 2011, showing tsunami waves
hitting the coast of Minamisoma in Fukushima prefecture, Japan.
Credits: Sadatsugu Tomizawa CC BY-NC-ND 2.0
The finding further validates an approach developed by Song and his colleagues that uses GPS technology to detect a tsunami’s size and strength for early warnings.
The JPL-managed Global Differential Global Positioning System (GDGPS)
is a very accurate real-time GPS processing system that can measure
seafloor movement during an earthquake.
As the land shifts, ground
receiver stations nearer to the epicenter also shift.
The stations can
detect their movement every second through real-time communication with a
constellation of satellites to estimate the amount and direction of
horizontal and vertical land displacement that took place in the ocean.
They developed computer models to incorporate that data with ocean floor
topography and other information to calculate the size and direction of
a tsunami.
“By identifying the important role of the horizontal motion of the
seafloor, our GPS approach directly estimates the energy transferred by
an earthquake to the ocean,” Song said.
“Our goal is to detect a
tsunami’s size before it even forms, for early warnings.”
