It was only 50 years ago when scientists had tangible evidence that continents drift around the earth’s surface and established what drives their movement. The evidence revolved around several observations such as the map of the earth, which looks like a large jigsaw puzzle; fossils found on one continent that match fossils on neighbouring detached continents; the discovery of mid-ocean ridges deep beneath the sea; and, the symmetrical distribution of magnetic strips across the ocean ridges. That evidence overcame scepticism about this incredible fact: the earth’s surface moves.
Seismology, or the study of earthquakes, makes it possible to map the deep interior of our planet. The earth has a solid core akin to the yolk of a boiled egg, encircled by a softer layer similar to the egg white and the earth’s plates that compare to a thin outer eggshell. That shell is cracked. It is made up of slowly moving tectonic plates that converge to create mountains or diverge to make oceans.
The cycle of our cracked earth is far from fully understood. Fundamental questions still exist: where does the tectonic process originate from? And, how does a plate form, thicken and age? Despite having the technology to image from the subsurface down through practically the entire planet, the main challenge is that plates are ‘born’ in remote areas, deep beneath the oceans, making it difficult for scientists to study them.
In 2016 a dedicated team of scientists performed a large-scale marine experiment along the equator, across the Atlantic Ocean covering hundreds of kilometres of seafloor. The conditions at the bottom of the ocean are hostile, with underwater mountains ranging from two to five kilometres below sea level – many are active submarine volcanoes. The experiment called PI-LAB (Passive Imaging of the Lithosphere and Asthenosphere Boundary) used state-of-the-art equipment to determine different physical properties of the ocean floor particularly, along the Mid-Atlantic Ridge to reveal key information about the plates there. Ocean bottom seismometers were left lying on the seafloor for one year to record the vibrations of the earth and then recovered in 2017. I will be talking at Malta Café Scientifique about what we found on Wednesday at 7pm, Spazju Kreattiv, St James Cavalier in Valletta.
Being a member of the PI-LAB scientific team, I took part in the deployment and recovery missions of the experiment and I am now processing the recordings of distant earthquakes to image the underlying structures beneath the ocean.
The imaging process works in a similar fashion as in a medical CT scan but using seismic signals. This work follows on a similar study I did for the Hawaiian Islands, where the research shed new clues on the origin of the volcano there, which instead of being located at the plate boundary is peculiarly located in the middle of a plate.
Greater detail about the expedition and my research will be given during my upcoming Malta Café Scientifique’s talk.
For more information, visit http://bit.ly/MCSmay2018 .
Dr Matthew R. Agius is a research fellow at the National Oceanography Centre, University of Southampton, Waterfront Campus, United Kingdom.
Did you know?
• Paris Syndrome is a mental condition experienced by mostly Japanese tourists who are left traumatised after visiting Paris.
• The can opener was invented 48 years after cans were introduced.
• The first neon sign was made in 1923 for a Packard dealership.
• Count Alessandro Volta invented the first battery in the 18th century.
• More than 2,500 left-handed people are killed every year from using equipment meant for right-handed people.
• The average adult human has two to nine pounds of bacteria in his or her body.
For more trivia see: www.um.edu.mt/think
Sound bites
• A new study has linked more genes with depression. This meta-analysis covered 135,000 people with major depression and more than 344,000 controls to identify 44 genomic variants, or loci, that have a statistically significant association with depression.
www.sciencedaily.com/releases/2018/04/180426130031.htm
• The goal of brain implants is to read neuron activity and respond by activating them to move artificial limbs or stimulate lost senses. Researchers have developed a device that can help visually impaired people by projecting a holographic image into the top layer of the brain to activate dozens of neurons hundreds of times a second to simulate real patterns of activity, tricking our brain to perceive things that are not there.
www.sciencedaily.com/releases/2018/04/180430131923.htm
For more science news, listen to Radio Mocha on Radju Malta every Saturday at 11.05am.