Subscribe free to our newsletters via your
. Energy News .




TECTONICS
Alpine faults show new evidence for regular magnitude 8 earthquakes
by Staff Writers
Reno NV (SPX) Jul 31, 2012


University of Nevada - Reno seismologist Glenn Biasi spent eight days in the dense forests on the western side of the Southern Alps on the South Island of New Zealand to study the Alpine Fault, among the world's longest, straightest and fastest moving plate boundary faults. Photo courtesy University of Nevada, Reno. Credit: Photo courtesy University of Nevada, Reno.

A new study published in the prestigious journal Science, co-authored by University of Nevada, Reno's Glenn Biasi and colleagues at GNS Science in New Zealand, finds that very large earthquakes have been occurring relatively regularly on the Alpine Fault along the southwest coastline of New Zealand for at least 8,000 years.

The Alpine Fault is the most hazardous fault on the South Island of New Zealand, and about 80 miles northwest of the South Island's main city of Christchurch.

The team developed evidence for 22 earthquakes at the Hokuri Creek site, which, with two additional from nearby, led to the longest continuous earthquake record in the world for a major plate boundary fault.

The team established that the Alpine Fault causes, on average, earthquakes of around a magnitude 8 every 330 years. Previous data put the intervals at about 485 years.

Relative motion of Australian and Pacific plates across the Alpine Fault averages almost an inch per year. This motion builds up, and then is released suddenly in large earthquakes.

The 530-mile-long fault is among the longest, straightest and fastest moving plate boundary faults in the world. More than 23 feet of potential slip has accumulated in the 295 years since the most recent event in A.D. 1717.

Biasi, working with the GNS Science team led by Kelvin Berryman, used paleoseismology to extend the known seismic record from 1000 years ago to 8,000 years ago. They estimated earthquake dates by combining radiocarbon dating leaves, small twigs and marsh plants with geologic and other field techniques.

"Our study sheds new light on the frequency and size of earthquakes on the Alpine Fault. Earthquakes have been relatively periodic, suggesting that this may be a more general property of simple plate boundary faults worldwide," Biasi, of the Nevada Seismological Laboratory said.

"By comparison, large earthquakes on California's San Andreas Fault have been less regular in size and timing."

"Knowing the average rate of earthquakes is useful, but is only part of the seismic hazard equation," he said.

"If they are random in time, then the hazard does not depend on how long it has been since the most recent event.

"Alpine Fault earthquakes are more regular in their timing, allowing us to use the time since the last earthquake to adjust the hazard estimate. We estimate the 50-year probability of a large Alpine fault earthquake to be about 27 percent."

A magnitude 7.1 earthquake centered near Christchurch, the largest city in the South Island of New Zealand, caused extensive damage to buildings on Sept. 2, 2010, and no deaths.

On Feb. 22, 2011, a triggered aftershock measuring magnitude 6.3, with one of the strongest ground motions ever recorded worldwide in an urban area, struck the city killing 185 people.

Among other seismic work, Biasi has conducted research on earthquake recurrence on the San Andreas Fault and is a contributor to the Uniform California Earthquake Rupture Forecast-3 project, which is developing earthquake probabilities for the California Earthquake Authority. He is a research associate professor in the College of Science's Mackay School of Earth Sciences and Engineering.

.


Related Links
University of Nevada, Reno
Tectonic Science and News






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

Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle








TECTONICS
Colliding continents affected climate
Washington (UPI) Jul 23, 2012
An alteration of seawater chemistry caused by a continental collision 50 million years ago has been linked with past climate changes, researchers say. "Seawater chemistry is characterized by long phases of stability, which are interrupted by short intervals of rapid change," geoscientist Ulrich Wortmann of the University of Toronto said. Wortmann and co-author Adina Paytan of the ... read more


TECTONICS
EDF first-half profits up on hydro, renewables

Hunter-gatherers, Westerners use same amount of energy, contrary to theory

BSU starts second phase of largest geothermal system in U.S.

Roadmap for a Sustainable Energy System in the Dominican Republic

TECTONICS
Philippines offers up China-claimed oil prospects

French Total signs Iraqi Kurdistan oil deal

BP plunges into net loss on huge $5.0-bn writedown

US imposes new sanctions on Iran oil sector

TECTONICS
SeaRoc to provide full installation services on Narec's Offshore Anemometry Hub

Italian police seize giant wind farm in mafia probe

GL Garrad Hassan releases update of WindFarmer 5.0

U.S moves massive wind farm plan forward

TECTONICS
China denies EU solar dumping

Photovoltaics from any semiconductor

NIST measurement advance could speed innovation in solar devices

Beijing denies solar panel dumping amid EU row

TECTONICS
TEPCO receives $12.8 billion public bailout

EnBW says won't sue Germany over nuclear exit

Automatic shutdown at S. Korea nuclear reactor

Anti-nuclear protesters surround Japan parliament

TECTONICS
German National Academy of Sciences issues a critical statement on the use of bioenergy

U.S, Australian navies focus on new fuels

Strategies to improve renewable energy feedstocks

Brazil to build first algae-based biofuel plant

TECTONICS
China to land first moon probe next year

China launches Third satellite in its global data relay network

Looking Forward to Shenzhou 10

Argentina, China ink space cooperation deal

TECTONICS
Global warming is due to humans: US ex-skeptic

North America may face 'megadrought'

Climate-change skeptic has 'turnaround'

US drought woes deepen




The content herein, unless otherwise known to be public domain, are Copyright 1995-2014 - Space Media Network. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA Portal 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