Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Sandia underground geo-tools aid in earthquake research

08.03.2005


Geothermal researchers at Sandia National Laboratories have developed sensors that can be placed in hotter and higher-pressure underground environments than previous instruments, a capability that is allowing geologists worldwide to make more precise measurements of subterranean conditions before and after large earthquakes occur.

The researchers hope the new sensors will provide geologists with a better understanding of earthquake-related phenomena and possibly provide more sensitive measurements of warning signs for large earthquakes such as the devastating 9.0 magnitude earthquake near Sumatra on Sunday, Dec. 26.

Sandia is a National Nuclear Security Administration laboratory.



Extremely accurate

Lab engineers Joe Henfling and Randy Normann with technologist David Chavira are building a series of increasingly resilient and sensitive instruments that are being used by the U.S. Geological Survey and others to study a number of earthquake-related phenomena.

Sandia engineers, who have worked for decades with the geothermal resources experts around the U.S., have gained a reputation for building reliable instruments that can operate in the high-temperature and high-pressure environments of a geothermal reservoir, explains Normann. Sandia-designed instruments continue to push the envelope to provide scientists with better data, he says.

Using Quartzdyne quartz pressure and temperature sensors with a relative resolution of less than 0.005 psi and .01 degree C makes the instruments extremely accurate, Normann says.

"We can monitor extremely small temperature and pressure changes in deep reservoirs," he says.

Sandia began working with the USGS two years ago on a program to monitor geothermal wells, which contain water in the pore spaces between grains in the hot rock. Using pressure and temperature tools to analyze earthquake data shows potential because reservoirs can sometimes be five to 10 miles long, creating a much larger area of sensitivity to the waves generated by quakes than the relatively small area used by seismic detectors.

"We also have the potential to put tools much deeper in hotter zones below the reservoir where the rock is over 200 degrees C," says Normann.

California’s Long Valley is one of several places where distant earthquakes are registered through a phenomenon called remotely triggered seismicity, says Evelyn Roeloffs, a Vancouver, Wash.-based USGS geophysicist. Large earthquakes, sometimes far away, create waves that cause bursts of micro-earthquakes in the area. Some persist for days after other seismic activity has returned to normal.

"We have a history of monitoring in Long Valley," she says. "In the past, we couldn’t record the pressures frequently enough to determine if there was any response to seismic activity. Now we are recording temperatures and pressures once every 2.5 seconds. We want to see if we can get better timing of the pressure changes in the rock relative to the seismic activity and if there are temperature changes."

Sometimes pressures in the fluids in the reservoirs increase after earthquakes and movements in the rocks can be measured. "If we could put tools in deeper and hotter wells, we could get better information," Roeloffs says.

Drilling deeper

At New Mexico Tech in Socorro, geophysicist Harold Tobin is also discussing a deeper and hotter regime for the placement of Sandia’s geothermal tools.

"We are still in the planning stages, but in about a year and a half we are going to start a big drilling project to bore into a tectonic feature similar to the one where the Sumatra earthquake occurred," says the associate professor. "The site is off the coast of Japan in the Nankai Trough Seismogenic Zone. The target is six kilometers (3.6 miles) beneath the ocean’s floor in water two kilometers (1.2 miles) deep, in a subduction zone where some of the largest earthquakes on the planet have been generated. In 1944 and again in 1946 the quakes generated significant tidal waves, or tsunamis, as well.

"We are looking to place instruments in the fault zone to better understand the precursors of earthquakes and to learn about the physics of these zones in terms of storing stress and releasing it as the plates slip and displace," he says. "We will need instruments that can withstand temperatures of 150 to 180 C, which are well up in the range where normal electronics don’t work."

Basically, scientists understand that the friction between two moving rock faces causes them to stick and build up pressure until it overcomes the friction, moving the rock and creating an earthquake.

"There’s a theory that the pore fluid pressure in the rocks affects this dynamic," Tobin says. High water pressure may push faces apart, allowing slippage of the rock faces.

"When earthquakes happen may be governed by fluid pressure, which is why the instruments down hole are so important," he says.

Going barefoot

The secret to Sandia’s success in designing robust high-temperature tools is in part a material called Silicon-on-Insulator (SOI), which isolates the transistors from one another and greatly reduces thermally generated current leaks that occur on normal silicon-designed components, says Normann.

With silicon-based electronics, the resistance of the silicon material breaks down as heat increases and it begins to act increasingly like a conductor of electricity. The SOI reduces the frequency of breakdowns by a factor of 100, he says. Engineers have also worked on a phenomenon called metal migration at silicon-metal junctions by thickening the wires there, reducing the current, and ultimately prolonging the life of the junctions.

"These types of components were originally developed for aircraft and other high reliability applications," Normann says. In fact Sandia is working with the Air Force on similar extreme environmental electronics technology. The ultimate goal is something called "going barefoot," says Normann, a term that means building components so rugged that they will not need any heat shielding to protect them.

Will Keener | EurekAlert!
Further information:
http://www.sandia.gov

More articles from Earth Sciences:

nachricht Climate satellite: Tracking methane with robust laser technology
22.06.2017 | Fraunhofer-Gesellschaft

nachricht How reliable are shells as climate archives?
21.06.2017 | Leibniz-Zentrum für Marine Tropenforschung (ZMT)

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Quantum thermometer or optical refrigerator?

23.06.2017 | Physics and Astronomy

A 100-year-old physics problem has been solved at EPFL

23.06.2017 | Physics and Astronomy

Equipping form with function

23.06.2017 | Information Technology

VideoLinks
B2B-VideoLinks
More VideoLinks >>>