Subscribe free to our newsletters via your
. 24/7 Space News .

Cascadia initiative to monitor Northwest Pacific seismic risks
by Staff Writers
San Francisco CA (SPX) Aug 19, 2015

Researchers on the Research Vessel Oceanus retrieve an ocean-bottom seismometer during a 2014 expedition supporting the Cascadia Initiative. Image courtesy Pat Kight. For a larger version of this image please go here.

Early data coming in from a massive, four-year deployment of seismometers onshore and offshore in the Pacific Northwest are giving scientists a clearer picture of the Cascadia subduction zone, a region with a past and potential future of devastating "megathrust" earthquakes.

The preliminary results from the Cascadia Initiative include a report of previously undetected, small earthquakes offshore, and seismic imaging that reveals new offshore structures at the subduction zone. The reports, published as a focus section in the September-October 2015 issue of Seismological Research Letters (SRL), also provide an update on how well the Initiative's instruments are operating, including a look at how seafloor pressure monitors can detect tsunamis in the region.

The Cascadia subduction zone (CSZ) is a 1,100-(680 mile) kilometer Pacific fault that runs roughly from Cape Mendocino, California in the south to northern Vancouver Island, British Columbia. The zone marks the place where the Juan de Fuca and Gorda tectonic plates slip beneath the North American plate at a rate of about 2.3 to 4 centimeters (.9 to 1.6 inches) per year.

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. These megathrust quakes include the 2004 magnitude 9.1 Sumatran Andaman earthquake that devastated parts of Indonesia, and the 2011 magnitude 9.0 Tohoku earthquake in Japan.

Although the CSZ has been relatively quiet in recent years, researchers have compiled a historical record of full and partial ruptures of the massive fault, with a magnitude 9.0 earthquake and tsunami last occurring in 1700. Scientists estimate that these megathrust quakes occur at 400 to 600-year intervals. Agencies such as the U.S. Federal Emergency Management Agency (FEMA) and others have warned of catastrophic damage along the U.S. Northwest coast in the wake of a megathrust quake.

Funded from 2011 to 2015 by the National Science Foundation, the Cascadia Initiative was designed in part to collect information on the potential seismic threat of the CSZ. The project includes 27 new inland seismic stations, upgrades to 232 other land stations, and the deployment of 60 new seismometers on the ocean bottom, spread across the tectonic plates. The data collected by the initiative is openly available to the full scientific community in a database managed by the Incorporated Research Institutions for Seismology (IRIS) Data Management Center.

The project "offers a unique opportunity to image the seismic structures associated with an entire plate, including its spreading center and subduction zone, within an easily accessible part of the continental and offshore United States," said University of Massachusetts Amherst researcher Haiying Gao, a guest editor of the SRL focus section.

"I don't think we can predict the time or location of the next megathrust earthquake in the CSZ based on the current research progress," Gao cautioned. "Nevertheless, the Cascadia Initiative significantly contributes to a better understanding of the structure of the downgoing oceanic plates and thus to the assessment and mitigation of potential seismic and tsunamic hazards."

For instance, a paper by New Mexico Tech researchers Emily Morton and Susan Bilek describes 96 small new earthquakes occurring in 2011 and 2012 that were detected with the help of the Initiative's ocean floor seismometers.

These earthquakes occurred in the shallow, offshore "locked" part of the CSZ, where the fault is stuck in place, and had not been observed by land-based instruments. Detecting and locating these small seismic events can help researchers understand how strain on the megathrust fault may be changing, and to help predict how the megathrust might behave during a large rupture.

The seismic data collected by the Initiative has also helped Gao and her colleague Yang Shen at the University of Rhode Island, along with another study by Columbia University scientist Helen Janiszewski and Cornell University researcher Geoffrey Abers, to compile a picture of the CSZ structure that points to new places where the crushing pressure of subduction is squeezing water from and transforming rock at the trench where the Juan de Fuca plate is bending under the North American plate.

The newly deployed seafloor seismometers, said Gao, have offered an unprecedented look at how released fluid can affect the fault's strength and behavior at the offshore trench.

Offshore instruments are important tools for observing and detecting tsunami risks in the region, according to a paper by Anne Sheehan of the University of Colorado Boulder and colleagues. They compared readings from several types of seafloor pressure gauges to study the tsunami caused by the 2012 Haida Gwaii earthquake, to evaluate how well the gauges could detect the timing and size of a tsunami.

Thanks for being here;
We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain.

With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords.

Our news coverage takes time and effort to publish 365 days a year.

If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.
SpaceDaily Contributor
$5 Billed Once

credit card or paypal
SpaceDaily Monthly Supporter
$5 Billed Monthly

paypal only


Related Links
Seismological Society of America
Tectonic Science and News

Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks DiggDigg RedditReddit GoogleGoogle

Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News

Rocks provide clues for unearthing underground fault connections
Irvine CA (SPX) Aug 05, 2015
Stacked in gravity-defying arrangements in the western San Bernardino Mountains, near the San Andreas Fault, granite boulders that should have been toppled by earthquakes long ago resolutely remain. In exploring why these rocks still stand, researchers have uncovered connections between Southern California's San Jacinto and San Andreas faults that could change how the region plans for future ear ... read more

From a million miles away, NASA camera shows moon crossing face of Earth

Russia to conduct simulated flight program to Moon, Mars over 4 years

NASA Could Return Humans to the Moon by 2021

Smithsonian embraces crowdfunding to preserve lunar spacesuit

One Decade after Launch, Mars Orbiter Still Going Strong

One Decade after Launch, Mars Orbiter Still Going Strong

Salt flat indicates some of the last vestiges of surface water on Mars

Mars Rovers and the Last Moonwalker to Invade Poland in September

First Time Ever: ISS Crew Eats Food Grown in Outer Space

Gecko Grippers Moving On Up

US, Russia, China to Explore Benefits of Outer Space for ASEAN

First bite of space-grown lettuce is 'awesome'

China's space exploration potential has US chasing its own tail

China to deploy space-air-ground sensors for environment protection

Chinese earth station is for exclusively scientific and civilian purposes

Cooperation in satellite technology put Belgium, China to forefront

First Use of ISS Astronaut Pictures for Light Pollution Studies

ISS to Open Research Facility for Materials Science Research by 2017

NASA renews $490M contract with Russian Space Agency

NASA Completes Selection of Crew Members for 2017 ISS Missions

NASA selects contractor to prepare launch structure for SLS

ILS concludes Proton launch failure investigation

Intelsat 34 fueled for heavy-lift mission with Ariane 5

India to launch 9 US satellites in 2015, 2016

Tenth transiting 'Tatooine'

Astronomers discover new planet orbiting two stars

Scientists solve planetary ring riddle

Overselling NASA

Gaming fans resurrect beloved 1980s ZX Spectrum in UK

Scientists achieve major breakthrough in thin-film magnetism

Surprising discoveries about 2-D molybdenum disulfide

Australia court sides with Internet firms in piracy row

The content herein, unless otherwise known to be public domain, are Copyright 1995-2014 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement All images and articles appearing on Space Media Network have been edited or digitally altered in some way. Any requests to remove copyright material will be acted upon in a timely and appropriate manner. Any attempt to extort money from Space Media Network will be ignored and reported to Australian Law Enforcement Agencies as a potential case of financial fraud involving the use of a telephonic carriage device or postal service.