New research published in the journal ‘Science Advances’, has focused their study off the west coast of North America giving seismologists a better understanding of what one scientist describes as “the single greatest geophysical hazard to the continental United States”.
Zach Eilon, a geophysicist at the University of California Santa Barbara, has developed a new method that uses an array of scientific instruments spread across the sea floor to measure shock waves that travel through the planet’s crust. “Because we think this particular phenomenon is strongly related to temperature and to molten rock beneath the Earth, this is a technique that can be applied to volcanoes to get a better sense of their plumbing system,” says Eilon.
Eilon’s research targets the Juan de Fuca plate, which runs several hundred kilometers off the coast between southern British Columbia and northern California and is the youngest and smallest of the planet’s 13 major tectonic plates. The collision zone in this region has the potential to generate massive quakes and destructive tsunamis, which occur when the plates overcome friction and slip past one another, quickly displacing huge amounts of water.
His data suggest the interior of the Juan de Fuca plate is cooler than previously believed, meaning the edge that is being pushed westward below the North American plate is able to bring with it more water. The water acts as a lubricant and increases the likelihood of the slipping that leads to a quake.
Geoff Abers, an earth-sciences professor at Cornell University who co-authored the paper with Eilon, said improvements in sea-floor technology and the sheer number of sensors that were deployed make this project the first time researchers have been able to study an entire tectonic plate in the ocean. “We’re not directly looking at the just earthquake cycles, but we’re looking at the broader, theoretical framework for how the Earth works and getting a much better handle on that,” Abers said.
Thank you for your continued support. We’re now about half way there.
COMING NEXT: WAR AND EARTHQUAKES; IS THERE A CONNECTION
The thinning is related to the cooling of Earth’s interior prompted by the splitting of the supercontinent Pangaea, which broke up into the continents that we have today, said Harm Van Avendonk, the lead author of the study and a senior research scientist at The University of Texas Institute for Geophysics. The findings, published in Nature Geosciences on Dec. 12, shed light on how mantle plumes and plate tectonics has influenced the cooling of the Earth’s mantle throughout geologic history.
The mantle is the very hot, but mostly solid, layer of rock between the Earth’s crust and core. Magma from the mantle forms oceanic crust when it rises from the mantle to the surface at spreading centers and cools into the rock that forms the very bottom of the seafloor. The Earth’s mantle has been cooling almost from its creation.
“It’s important to note the Earth seems to be cooling a lot faster now than it has been over its lifetime,” Van Avendonk said. “The current rate of mantle plumes allows Earth to cool much more efficiently than it did in the past.”
The research that led to the connection between the splitting of the supercontinent and crust thickness started when Van Avendock and Ph.D. student Jennifer Harding, a study co-author, noticed an unexpected trend when studying existing data from young and old seafloor. They analyzed 234 measurements of crustal thickness from around the world and found that, on a global scale, the oldest ocean crust examined – 170 million year old rock created in the Jurassic – is about one mile thicker than the crust that’s being produced today.
The link between crust thickness and age prompted two possible explanations – both related to the fact that hotter mantle tends to make more magma. Mantle plumes could have thickened the old crust by covering it in layers of lava at a later time. Or, the mantle was hotter in the Jurassic than it is now.
The finding that splitting up Pangea cooled the mantle is important because it gives a more nuanced view of the mantle temperature that influences tectonics on Earth.
This is an update to an article I wrote back in the second week of November telling of the supermoon on Nov. 14th and the likelihood of large earthquakes to occur. Just 48 hours after my published article, New Zealand is hit with a magnitude 7.8 quake followed by four additional quakes measuring over 6.2 magnitude. On November 21st a magnitude 6.9 quake hits Japan, and on November 24th a 7.0 mag. hits El Salvador.
As it relates to a supermoon, it is the additional close passage to Earth generating an even greater gravitational tug causing tide fluctuations. November 14th’s full moon was the biggest and brightest since 1948. It is called a supermoon because the full phase is taking place at the moon’s closest point in its orbit around the Earth, also called the perigee. The full moon won’t come this close to Earth again until November 25, 2034.
Historically, my published research has identified a 14 day window prior to, and 14 day post period of a full lunar eclipse event. In different, but similar ways does a supermoon have its effects on all fluid, not just oceans. I call it ‘fluid displacement’ which includes magma, oil, and certain processes of natural gas. It is the expansion (or contraction) of fluids on tectonic plates which cause the increase of larger earthquakes or volcanic eruptions.
There is yet another supermoon is coming our way on December 14th 2016. However, the moon does not come as close as last months, but for those that missed Novembers you have one more chance to visit your local astronomy clubs who no doubt will have their telescopes pointed to the sky and are more than happy to share their passions.