• HOME
  • NEWS
  • EXPLORE
    • CAREER
      • Companies
      • Jobs
    • EVENTS
    • iGEM
      • News
      • Team
    • PHOTOS
    • VIDEO
    • WIKI
  • BLOG
  • COMMUNITY
    • FACEBOOK
    • INSTAGRAM
    • TWITTER
  • CONTACT US
Wednesday, September 27, 2023
BIOENGINEER.ORG
No Result
View All Result
  • Login
  • HOME
  • NEWS
  • EXPLORE
    • CAREER
      • Companies
      • Jobs
        • Lecturer
        • PhD Studentship
        • Postdoc
        • Research Assistant
    • EVENTS
    • iGEM
      • News
      • Team
    • PHOTOS
    • VIDEO
    • WIKI
  • BLOG
  • COMMUNITY
    • FACEBOOK
    • INSTAGRAM
    • TWITTER
  • CONTACT US
  • HOME
  • NEWS
  • EXPLORE
    • CAREER
      • Companies
      • Jobs
        • Lecturer
        • PhD Studentship
        • Postdoc
        • Research Assistant
    • EVENTS
    • iGEM
      • News
      • Team
    • PHOTOS
    • VIDEO
    • WIKI
  • BLOG
  • COMMUNITY
    • FACEBOOK
    • INSTAGRAM
    • TWITTER
  • CONTACT US
No Result
View All Result
Bioengineer.org
No Result
View All Result
Home NEWS Science News

Balanced rocks set design ground motion values for New Zealand dam

Bioengineer by Bioengineer
June 15, 2021
in Science News
Reading Time: 3 mins read
0
Share on FacebookShare on TwitterShare on LinkedinShare on RedditShare on Telegram

IMAGE

Credit: Mark Stirling

For the first time, researchers have used precariously-balanced rocks to set the formal design earthquake motions for a major existing engineered structure–the Clyde Dam, the largest concrete dam in New Zealand.

Mark Stirling of the University of Otago and colleagues identified and assessed the ages of these gravity-defying rock formations located about 2 kilometers from the dam site, using these data to determine the peak ground accelerations that the rocks could withstand before toppling.

This in turn was used to set the Safety Evaluation Earthquake (SEE) spectrum for the dam, or the expected peak earthquake ground motions occurring with a return period of 10,000 years that governs the safety assessment and seismic design of the structure.

As the researchers report in the Bulletin of the Seismological Society of America, the peak ground acceleration for the new SEE spectrum, developed from the rock data as well as an updated seismic hazard model for the region, is significantly reduced compared to their preliminary estimates developed in 2012.

However, the new design ground motion values are similar to those used–by chance–when the dam was built in the 1980s. “There is nothing that needs to be done in the way of dam strengthening,” said Stirling. “However, the study shows all the relevant authorities that the dam is compliant given the modern regulations.”

The study also “serves as an important proof-of-concept for future applications of fragile geologic features (FGFs) in engineering design,” Stirling and his colleagues write.

FGFs are especially useful in setting engineering design parameters in places where the period between relevant earthquakes is very long–10,000 years or more. In these cases, the geologic features can help test probabilistic seismic hazard estimates. While seismologists have explored the usefulness of these features for other engineering design projects, such as the canceled Yucca Mountain nuclear waste repository in Nevada and the Diablo Canyon power plant in California, the Clyde Dam is the first to use fragile features to set design ground motion.

The Clyde Dam is located in the Central Otago “Range and Basin” region of the southern part of New Zealand’s South Island. On a broad plateau located southwest of the dam called Cairnmuir flat, outcrops of schist rock that stick up above the landscape are carved by erosion into potentially unstable configurations.

In a painstaking effort, Stirling and colleagues identified these precariously-balanced rocks and took field measurements of their geometries to estimate their fragility. Then the researchers analyzed the formations using radionuclide data that estimate how long a rock surface has been exposed to the atmosphere. These data can show how long a rock has been balanced in a specific position.

“In terms of data collection, it was the FGF age estimation that was most challenging,” said Stirling. “It required specialist input, hard physical work, and there were usually large uncertainties in interpreting the dates to say how long the FGFs had been fragile.”

By combining these data with information on past earthquakes along the nearby Dunstan fault, Stirling and colleagues concluded that the rocks at Cairnmuir flat had been poised in their unstable positions since at least 24,000 years ago. This suggests that all of them have survived at least two Dunstan fault earthquakes.

The researchers then developed a fragility distribution of all precariously-balanced rocks in their study, based on peak ground acceleration, to determine the peak ground accelerations most likely to topple any random fragile rock structure with greater than 95% probability. This information was used to recommend a new SEE spectrum for the dam site.

Preliminary probabilistic seismic hazard calculations for the site suggested that “the FGFs in the area would be knocked down by these strong ground motions if they occurred–it’s easy to roughly estimate the fragility of the features by eye in the field,” Stirling explained. But since the features are still standing tall, it was then only a matter of time and research, he added, before the new Clyde Dam hazard estimates were revised.

###

Media Contact
Becky Ham
[email protected]

Related Journal Article

http://dx.doi.org/10.1785/0120210026

Tags: Civil EngineeringEarth ScienceGeophysics/GravityPlate Tectonics
Share12Tweet8Share2ShareShareShare2

Related Posts

Associate Prof Rohit Ramchandra

A novel role discovered for vagus nerve

September 27, 2023
Patients who quit smoking after percutaneous coronary intervention do as well as non-smokers – unless they had smoked heavily

Patients who quit smoking after percutaneous coronary intervention do as well as non-smokers – unless they had smoked heavily

September 27, 2023

THE LANCET: Gender inequalities worsen women’s access to cancer prevention, detection and care; experts call for transformative feminist approach

September 27, 2023

Double trouble: Infamous “eagle killer” bacterium produces not one, but two toxins

September 26, 2023
Please login to join discussion

POPULAR NEWS

  • blank

    Microbe Computers

    59 shares
    Share 24 Tweet 15
  • A pioneering study from Politecnico di Milano sheds light on one of the still poorly understood aspects of cancer

    35 shares
    Share 14 Tweet 9
  • Fossil spines reveal deep sea’s past

    34 shares
    Share 14 Tweet 9
  • Scientists go ‘back to the future,’ create flies with ancient genes to study evolution

    75 shares
    Share 30 Tweet 19

About

We bring you the latest biotechnology news from best research centers and universities around the world. Check our website.

Follow us

Recent News

A novel role discovered for vagus nerve

Patients who quit smoking after percutaneous coronary intervention do as well as non-smokers – unless they had smoked heavily

THE LANCET: Gender inequalities worsen women’s access to cancer prevention, detection and care; experts call for transformative feminist approach

Subscribe to Blog via Email

Enter your email address to subscribe to this blog and receive notifications of new posts by email.

Join 56 other subscribers
  • Contact Us

Bioengineer.org © Copyright 2023 All Rights Reserved.

No Result
View All Result
  • Homepages
    • Home Page 1
    • Home Page 2
  • News
  • National
  • Business
  • Health
  • Lifestyle
  • Science

Bioengineer.org © Copyright 2023 All Rights Reserved.

Welcome Back!

Login to your account below

Forgotten Password?

Retrieve your password

Please enter your username or email address to reset your password.

Log In