A
"subduction zone" is a place where one tectonic plate slides under another plate, usually resulting in the formation of mountains and causing earthquakes and volcanic activity.
Full definition
State geologists analyze projected impacts of
Cascadia Subduction Zone earthquake, magnitude 9.0, and expect tens of thousands of casualties in the...
U.S. Geological Survey scientist Jeanne Hardebeck calculated the frictional strength
of subduction zone faults worldwide, and the stresses they are under.
Thus, the study could improve the understanding of the geochemical processes
in subduction zones of the earth.
Both these analyses showed that zircons from as far back as 4.38 billion years ago crystallized in relatively cool conditions, such as
at subduction zones where water and magma interact at the intersection of tectonic plates.
In fact, lava emerging from hotspot volcanoes is known to differ chemically and isotopically from lava from other volcanoes, such as those erupting at
subduction zones where Earth's crust dives into the upper mantle.
Recent fieldwork in Alaska's Aleutian Islands suggests that a presently «creeping» section of the Aleutian
Subduction Zone fault could potentially generate an earthquake great enough to send a large tsunami across the Pacific to Hawaii.
The Cascadia
Subduction Zone off the coast of the Pacific Northwest has all the ingredients for making powerful earthquakes — and according to the geological record, the region is due for its next «big one.»
To improve seismic hazard assessment along
subduction zones as well as other dangerous faults such as continental transforms, we need a set of open software tools to explore alternatives, we need a trans - national dialogue to discuss and vet our different ideas and approaches, and we need to conduct prospective tests of global models that are based on these various national strategies.
Meng says the findings show that quakes can grow to large, potentially dangerous magnitudes far
from subduction zones by jumping from fault to fault.
Megathrust earthquakes can generate destructive tsunamis and are a serious hazard facing communities located
near subduction zones.
That variety implies that almost any scenario is possible in another part of the Pacific Rim where quake risk is thought to be high — along the Cascadia
subduction zone offshore of Washington, Oregon, and other parts of the western United States and Canada.
He said that event made clear that structural damage is only one of the serious threats raised
by subduction zone earthquakes.
This study is the first to identify geological evidence for repeated prehistoric tsunamis along a creeping part of the eastern
Aleutian subduction zone located between the 1946 and 1957 earthquakes.
«Understanding the thickness of the plate is important to understanding how plates move around, both when they form at mid-ocean ridges and later on when the material goes back down into the Earth
through subduction zones such as those in Cascadia, the Andes, Japan and Indonesia,» said Warren, assistant professor in the Department of Geological Sciences in the College of Earth, Ocean, and Environment.
The GPS network detected the slow slip events occurring on the Hikurangi
subduction zone plate boundary in the weeks and months following the Kaik?ura earthquake.
Magmas formed
above subduction zones contain important amount of water that is essentially degassed during volcanic eruptions or upon magma cooling and solidification at depth.
The best available evidence indicates that
subduction zone quakes occur, on average, every 500 to 600 years, but the intervals between events have been as short as short as 100 to 300 years.
In high - pressure and high - temperature X-ray measurements that were partly conducted at DESY, scientists created conditions similar to those in so -
called subduction zones where an oceanic plate dives under the continental crust.
Instead, the new finding adds evidence that gravity pulling the plates
into subduction zones may drag them across the globe.
There it will seek out new species and habitats; it may also
study subduction zones, where oceanic crust is recycled back into the earth's mantle.
The findings, published in Nature Geoscience on Nov. 20, are important for understanding factors that influence earthquake and tsunami generation in Cascadia and at other
subduction zones around the world.
They simulated earthquakes with magnitudes between 9.0 and 9.6 originating at different locations along the Aleutian -
Alaska subduction zone, a 3,400 - kilometer (2,113 - mile) long ocean trench stretching along the southern coast of Alaska and the Aleutian Islands where the Pacific tectonic plate is slipping under the North American plate.
At
subduction zones like this throughout the globe, the tremendous strain built up in these crustal collisions has been released in the world's largest recorded earthquakes.
The study also increased the frequency of the most massive earthquakes, where the
entire subduction zone ruptures at once.
The simulations show that mantle plumes and the weaknesses they create could have actually initiated the
first subduction zones.
At
subduction zones such as these, an oceanic tectonic plate sinks (subducts) into the Earth's interior, the mantle.
Because the South
American subduction zone is so wide, it provides much resistance to migrate laterally, in particular in the centre.
The powerful shaking from several
recent subduction zone earthquakes around the world — notably the 9.0 - magnitude Tohoku earthquake in 2011 and the 8.2 - magnitude quake off the coast of Chile in 2014 — and geologic evidence from deep - sea cores of powerful quakes in the past now suggest that southern Cascadia could experience an earthquake as powerful as magnitude 9.3.
For example, the Caribbean coast of northern Colombia resembles a
classic subduction zone with the potential for tsunamigenic M > 8 earthquakes at millennial time scales, but the absence of a large earthquake since 1492 is cause for complacency among local populations.
The deep mantle - derived buoyancy, together with plate cooling at the surface, creates negative buoyancy that together explain the observations along the East Pacific Rise and surrounding
Pacific subduction zones.
«Measuring the strength of olivine is critical to understanding how strong tectonic plates are, which, in turn, matters to how plates break and
create subduction zones like those along the Cascadia plate, which runs down the west coast of Canada to the west coast of the United States,» said Warren, a geologist in the College of Earth, Ocean, and Environment.
Many people understand the damage that can be caused to structures, roads, bridges and utilities by ground shaking in these long - lasting types of earthquakes, such as the one that's anticipated on the Cascadia
Subduction Zone between northern California and British Columbia.
Named the Cascadia Initiative, it is rotating among
subduction zone segments offshore of Washington, Oregon and Northern California.
The Cascadia
subduction zone lies offshore from northern California to southwestern British Columbia, where two tectonic plates — the North America plate and the Juan de Fuca plate — come together to form an 800 - mile long earthquake fault.
June 17, 2013 — A
new subduction zone forming off the coast of Portugal heralds the beginning of a cycle that will see the Atlantic Ocean close as continental Europe moves closer to America.
These initial results provide fundamental insights into the behavior of rare, very large earthquakes that may aid in preparation and early warning efforts for future tsunamis
following subduction zone earthquakes.
Now that Warren and her colleagues understand this size - effect, they are turning their attention to how temperature affects the strength of olivine, and more broadly, on where tectonic plates might break and give rise to
potential subduction zones.
In the early 1980s, two Caltech geophysicists, Tom Heaton and Hiroo Kanamori, compared Cascadia to active quake -
prone subduction zones along the coasts of Chile and Alaska and to the Nankai Trough off the coast of Japan.