Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Columbia research examines mega earthquake threats


New use for seismic reflection data: revealing the most dangerous fault lines on Earth

Researchers have found an important new application for seismic reflection data, commonly used to image geological structures and explore for oil and gas. Recently published in the journal Nature, new use of reflection data may prove crucial to understanding the potential for mega earthquakes.

Mladen Nedimovic, the lead author and a scientist at the Lamont-Doherty Earth Observatory, a member of the Earth Institute at Columbia University, examined reflection data collected on the northern Cascadia margin off the coast of Vancouver Island. Cascadia margin is an area where the north Pacific seafloor is being pushed under the continental margin of North America. Locations where oceanic plates are underthrusting the continents are known as subduction zones. Within subduction zones are enormous faults called megathrusts, the places where the two tectonic plates meet and interface one another. Megathrusts are the source of the largest and most devastating earthquakes on Earth.

From the reflection data, Nedimovic and his coauthors mapped the locked zone on the megathrust along the northern Cascadia margin, which hosts the populous cities of Vancouver and Seattle. Locked zones, where geological structures beneath the surface are tightly interfaced, build up enormous pressure as the Earth shifts. In 1700, the pressure beneath the Cascadia margin was released, resulting in a magnitude 9 earthquake that devastated the region. A magnitude 9 earthquake releases over 1000 times more energy than was released during the magnitude 6.8 Nisqually earthquake that shook Seattle two years ago.

Currently, dislocation and thermal modeling are used for mapping locked zones, however, both methods rely on many assumptions about Earth’s structure that may limit their accuracy. In fact, for the northern Cascadia margin, estimates of the locked zone using these techniques indicate that a 36-mile (~60 km) swath of land from the subduction trench toward Vancouver Island is locked. Nedimovic’s reflection analysis shows that it is more likely to be a 56-mile (~90 km) swath, extending the zone some 20 miles (~30 km) closer to land. If this is accurate, rapidly growing inland cities face a greater threat from megathrust earthquake hazards than previously anticipated. The occurrence rate for great earthquakes on the Cascadia megathrust is approximately every 200 to 800 years. We are currently within the timeframe where another large earthquake is expected, with the last earthquake having occurred over 300 years ago.

Seismic and aseismic slip occurs on different parts of a megathrust, at different depths, temperatures, and pressures, and due to different types of rock deformation. Brittle rock failure affects a narrow zone around the thrust where seismic slip is observed, and plastic deformation affects a much wider area above the thrust where the slip is slow and aseismic. Seismic reflection imaging reveals the variations in structures along the megathrust and can be used for detailed mapping of locked and slow-slipping zones.

"Deep seismic reflection images from Alaska, Chile, and Japan show a similar broad reflection band above the megathrust in the region of stable sliding and thin thrust reflections further seaward where the megathrust is locked, suggesting that reflection imaging may be a globally important predictive tool for determining the maximum expected rupture area in great subduction earthquakes," said Nedimovic. " Mega earthquakes have been instrumentally recorded for all three regions making them potential targets for a future investigation to confirm the reflection method and improve characterization of megathrust seismic hazards in the study area."

The northern Cascadia margin study was funded by the National Earthquake Hazards Reduction Program of the United States Geological Survey and by the Geological Survey of Canada. Mladen Nedimovic and his collaborators are submitting a proposal to National Science Foundation to carry out a megathrust seismic hazards characterization study along the southern Alaska margin.

Jill Stoddard | EurekAlert!
Further information:

More articles from Earth Sciences:

nachricht Receding glaciers in Bolivia leave communities at risk
20.10.2016 | European Geosciences Union

nachricht UM researchers study vast carbon residue of ocean life
19.10.2016 | University of Miami Rosenstiel School of Marine & Atmospheric Science

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

Im Focus: New Products - Highlights of COMPAMED 2016

COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.

In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...

Im Focus: Ultra-thin ferroelectric material for next-generation electronics

'Ferroelectric' materials can switch between different states of electrical polarization in response to an external electric field. This flexibility means they show promise for many applications, for example in electronic devices and computer memory. Current ferroelectric materials are highly valued for their thermal and chemical stability and rapid electro-mechanical responses, but creating a material that is scalable down to the tiny sizes needed for technologies like silicon-based semiconductors (Si-based CMOS) has proven challenging.

Now, Hiroshi Funakubo and co-workers at the Tokyo Institute of Technology, in collaboration with researchers across Japan, have conducted experiments to...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Resolving the mystery of preeclampsia

21.10.2016 | Health and Medicine

Stanford researchers create new special-purpose computer that may someday save us billions

21.10.2016 | Information Technology

From ancient fossils to future cars

21.10.2016 | Materials Sciences

More VideoLinks >>>