The most powerful earthquakes – such as those that shook Indonesia in 2004, Alaska in 1964, Chile in 1960 and the Pacific Northwest in 1700 – occur in subduction zones, areas of the sea floor just offshore where two tectonic plates meet and one dives beneath the other.
But not all subduction zones are created equal, and University of Washington researchers believe they have found a key to determine which subduction zones – or which specific areas within a subduction zone – might produce the most severe shaking when they rupture.
As the subducting plate slides beneath the upper plate, stress begins to build where the plates meet and the upper plate can deform to create a large structure called a forearc basin. The basin, a sort of a bowl-shaped depression, fills with sediment from nearby rivers that empty into the ocean. Over millions of years, the sediment typically piles to great depths, from a half-mile to nearly 2 miles, and in rare cases might reach 3 miles deep, said Christopher Fuller, a University of Washington doctoral student in Earth and space sciences.
The Cascadia subduction zone off the coasts of Washington, Oregon and northern California has forearc basins in several areas, Fuller said. As it moves to the east at 2 inches a year, the Juan de Fuca tectonic plate slides beneath the North American plate that contains the landmass of the Pacific Northwest. In the process, sediment as deep as 1½ miles is scraped off the top of the Juan de Fuca plate and is deformed into surface depressions on the North American plate, forming the basins where sediment from coastal rivers is deposited. The probability of large earthquakes is greatest in these areas.
The modeling could have implications in figuring out where, within a subduction zone such as Cascadia, great earthquakes are the most likely to occur, Fuller said. But the work is not applicable to every subduction zone because each has different characteristics. For instance, forearc basins do not play the same role in the subduction zone off the Indonesian island of Sumatra, where the massive 2004 earthquake triggered tsunamis that killed hundreds of thousands of people.
"You have to understand the nature of basins and how they work in each area before you can use them as an interpretive tool," Fuller said. "You cant just apply these correlations everywhere."
Vince Stricherz | EurekAlert!
Diving robots find Antarctic seas exhale surprising amounts of carbon dioxide in winter
16.08.2018 | National Science Foundation
Diving robots find Antarctic winter seas exhale surprising amounts of carbon dioxide
15.08.2018 | University of Washington
There are currently great hopes for solid-state batteries. They contain no liquid parts that could leak or catch fire. For this reason, they do not require cooling and are considered to be much safer, more reliable, and longer lasting than traditional lithium-ion batteries. Jülich scientists have now introduced a new concept that allows currents up to ten times greater during charging and discharging than previously described in the literature. The improvement was achieved by a “clever” choice of materials with a focus on consistently good compatibility. All components were made from phosphate compounds, which are well matched both chemically and mechanically.
The low current is considered one of the biggest hurdles in the development of solid-state batteries. It is the reason why the batteries take a relatively long...
New design tool automatically creates nanostructure 3D-print templates for user-given colors
Scientists present work at prestigious SIGGRAPH conference
Most of the objects we see are colored by pigments, but using pigments has disadvantages: such colors can fade, industrial pigments are often toxic, and...
Scientists at the University of California, Los Angeles present new research on a curious cosmic phenomenon known as "whistlers" -- very low frequency packets...
Scientists develop first tool to use machine learning methods to compute flow around interactively designable 3D objects. Tool will be presented at this year’s prestigious SIGGRAPH conference.
When engineers or designers want to test the aerodynamic properties of the newly designed shape of a car, airplane, or other object, they would normally model...
Researchers from TU Graz and their industry partners have unveiled a world first: the prototype of a robot-controlled, high-speed combined charging system (CCS) for electric vehicles that enables series charging of cars in various parking positions.
Global demand for electric vehicles is forecast to rise sharply: by 2025, the number of new vehicle registrations is expected to reach 25 million per year....
17.08.2018 | Event News
08.08.2018 | Event News
27.07.2018 | Event News
21.08.2018 | Medical Engineering
21.08.2018 | Physics and Astronomy
21.08.2018 | Power and Electrical Engineering