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 Impacts of mass coral die-off on Indian Ocean reefs revealed
21.02.2017 | University of Exeter

nachricht How much biomass grows in the savannah?
16.02.2017 | Friedrich-Schiller-Universität Jena

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Impacts of mass coral die-off on Indian Ocean reefs revealed

21.02.2017 | Earth Sciences

Novel breast tomosynthesis technique reduces screening recall rate

21.02.2017 | Medical Engineering

Use your Voice – and Smart Homes will “LISTEN”

21.02.2017 | Trade Fair News

VideoLinks
B2B-VideoLinks
More VideoLinks >>>