Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Scientists gauge earthquake hazards through study of precariously balance rocks

02.03.2007
Research by Nevada professors pinpoints certain seismic hazards, past and present, through California rock formations

A seismological research team from the University of Nevada, Reno is finding ways to make precariously balanced rocks talk. In so doing, they are unlocking valuable scientific information in assessing seismic hazards in areas throughout the West.

Their findings are shared in the January-February issue of American Scientist magazine. Scientists believe that zones of precarious rocks – rocks that have come close but haven't tipped over in the wake of a major seismic event – provide important information about seismic risk, its magnitude and its frequency. For a look at the article, click on: http://www.americanscientist.org/

template/AssetDetail/assetid/54437;jsessionid=baa9...?fulltext=true#54485

"There's really no long-term data to test seismic hazards other than precarious rocks," said Matthew Purvance, a postdoctoral scholar in geophysics at the University, who authored the article along with James Brune, professor in the Department of Geological Sciences and past director of the Nevada Seismological Laboratory, and Rasool Anooshehpoor, research professor in the Nevada Seismological Laboratory.

"By studying precariously balanced rocks, it can serve as an indicator that an earthquake of a sufficient size to topple a tippy rock has not occurred … at least for a very long time. We think this is a fundamental story that gives fundamental information on seismic hazards that has never been done before."

The data from the study is important, as it not only tests ground-motion probability, but can help further refine United States Geological Survey hazard methodologies that are used by engineers to formulate building codes. Purvance explained that seismologists and engineers since the late 1960s have increasingly followed a method known as probabilistic seismic-hazard analysis in trying to get a more firm grasp on earthquake probability. This analysis allows researchers to determine the number and magnitude of earthquakes on relevant faults. The study of precarious rocks, which act as "witnesses" to strong seismic events throughout history, has provided scientists an important research window to test the predictions of probability, Purvance said.

The team tested massive rocks of up to 1,000 pounds and more than 10,000 years old, measuring the force and angle it would take to tip them over. One of the more interesting aspects of the study was a technique used by Anooshehpoor, which measured the restoring force that has allowed the rock to remain upright through centuries of wear and the force of past strong seismic events.

Anooshehpoor's technique allowed the team to measure a tipping boulder's restoring force with a digital load cell and the rock's tilt with an inclineometer. The work wasn't easy. By pushing and pulling on the massive, bus-sized rocks with a series of wire cables, nylon straps, chains, pulleys, winches, hydraulic pistons, ground anchors and 4 by 4 blocks of wood, the team was able to record data for precarious rocks that had never been tested before.

"It gives us very useful information about the precarious rocks and further adds to the knowledge of gauging earthquake hazards," Purvance said, noting that it was work by Brune in the early 1990s with precarious rocks in southern California that led to the rocks becoming more widely recognized as an accurate barometer of seismic force and occurrence. "These measurements help better explain the story of how the rock has managed to withstand some of the forces of time and nature."

Added Anooshehpoor: "The rocks that we have studied are from large earthquakes and are so rare. If throughout history the world had tons of instruments and recorded many of these earthquakes, we probably wouldn't have the need to study precarious rocks. The lack of data has been a major problem in estimating ground motion. With this study, we've been provided with another opportunity to give the engineers the right information they need."

John Trent | EurekAlert!
Further information:
http://www.unr.edu

More articles from Earth Sciences:

nachricht In times of climate change: What a lake’s colour can tell about its condition
21.09.2017 | Leibniz-Institut für Gewässerökologie und Binnenfischerei (IGB)

nachricht Did marine sponges trigger the ‘Cambrian explosion’ through ‘ecosystem engineering’?
21.09.2017 | Helmholtz-Zentrum Potsdam - Deutsches GeoForschungsZentrum GFZ

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: The pyrenoid is a carbon-fixing liquid droplet

Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.

A warming planet

Im Focus: Highly precise wiring in the Cerebral Cortex

Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.

The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...

Im Focus: Tiny lasers from a gallery of whispers

New technique promises tunable laser devices

Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...

Im Focus: Ultrafast snapshots of relaxing electrons in solids

Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!

When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...

Im Focus: Quantum Sensors Decipher Magnetic Ordering in a New Semiconducting Material

For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.

Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

“Lasers in Composites Symposium” in Aachen – from Science to Application

19.09.2017 | Event News

I-ESA 2018 – Call for Papers

12.09.2017 | Event News

EMBO at Basel Life, a new conference on current and emerging life science research

06.09.2017 | Event News

 
Latest News

Rainbow colors reveal cell history: Uncovering β-cell heterogeneity

22.09.2017 | Life Sciences

Penn first in world to treat patient with new radiation technology

22.09.2017 | Medical Engineering

Calculating quietness

22.09.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>