Did the Earth move for you?

Just as a forensic scientist can find out what happened at a crime scene so a forensic seismologist can fingerprint the Earth to pinpoint unidentified explosions.

Geoscientist Terry Wallace of the University of Arizona is using data from some 3600 seismic stations – that normally look for volcanic and earthquake activity – to spot sinking submarines, industrial explosions, nuclear weapons testing, landslides, and other unidentified phenomena that make the Earth move.

Terry Wallace (image courtesy of Wallace)

Terry Wallace (image courtesy of Wallace)

Seismological tools and theory can be used as constraints to tell when an accident occurs or something that’s not accidental, like a nuclear explosion, explains Wallace, We can then put behind that some ideas of how big an explosion might be, or if it’s a landslide, how big the landslide might have been, or how far the rocks have fallen, for example.

He and his colleagues have confirmed, for instance, the when and where of Indian and Pakistani nuclear testing in the late 1990s. They have also studied the claim that Iraq tested a nuclear weapon in 1989. The alleged test was reported to have been carried out beneath Lake Rezazza, approximately 100 km southwest of Baghdad at 10:30h on 19 September. Wallace and his colleagues examined the global earthquake catalogues produced by the International Seismic Center and the US Geological Survey and say they reveal no seismic disturbances at all in Iraq that day. Moreover, they say there has been no seismicity within 50 km of the reported test site for the years 1980 to 1999. One problem with the assertion that no weapons testing took place, they point out, is that the detection threshold for these global catalogues was just magnitude 4.0 in 1989 so a smaller magnitude event may have not been picked up by the sensors. Thankfully, national catalogues for Israel, Jordan and Iran reported no seismic event in the region on that date either (19 September 1989).

Nuclear tests (image courtesy of Wallace)

Nuclear tests (image courtesy of Wallace)

The lower detection limit of modern seismic testing is only limited by the natural noises of the Earth. However, comparisons between results from different stations will reveal very fine detail. Explosions and earthquakes both generate seismic waves, but they have distinctive frequency signatures much like the tones of a voice, Wallace told Spotlight, Just as most children’s voices can be distinguished from adults, seismograms can be used to identify if a disturbance was caused by an earthquake or an explosion.

Two explosions (image courtesy of Wallace)

Two explosions (image courtesy of Wallace)

Wallace and his team have also analysed the seismic activity that occurred on the day the Russian submarine Kursk sank north of the Kola Peninsula. There were two explosions on 12th August 2000 associated with reports of this vessel sinking. There was a gap of two minutes between the explosions, the second of which was much bigger. Seismometers detected both up to 4500 km away. Calculations that compare results from different seismometers revealed that the second explosion was the equivalent of five tonnes of TNT exploding, which Wallace suggests was a warhead detonating. Our findings were corroborated when the Russians released their report in July this year, says Wallace.

The Kursk sank on 12th August 2000, in the Barents Sea

The Kursk sank on 12th August 2000, in the Barents Sea

Wallace revealed the latest details of his Earthly forensics investigations at the 2002 American Geophysical Union meeting in San Francisco in December. He revealed that he and his colleagues are investigating the sinking of the USS Scorpion submarine near the mid-Atlantic ridge in 1968, the sinking of another Russian sub in the Baltic in 1989, and the sinking of a large oil derrick in the North Sea that produced a 3.5-magnitude earthquake when it hit the ocean floor.

Water seismometers, or hydrophones, are even more sensitive to water rumblings than are the land-based versions. Using a hydrophone in the water, we can see the explosion of one stick of dynamite anywhere in the world. That’s how quiet the oceans are. So if you are going to hide something, don’t do it in the water, Wallace says.

The whole research effort for my group is to develop as big a portfolio as possible. This way, when we see an industrial accident where a fireworks factory blows up or a gasoline tank blows up, we have all the different kinds of seismic records we can get from that and we have characterized them. Then the next time something like that happens we have some experience to draw from. We’ve got some fingerprints left over to help us understand what is happening, Wallace adds.

Further reading

Suggested searches

Seismology
Seismic waves

Scientists conscripted in war on terrorism

The US National Academies of Science and Engineering and the Institute of Medicine are calling for the country to take full advantage of its scientific and engineering strengths to detect, thwart, and respond to terrorist attacks more effectively.

Science and technology have always provided humanity with a double-edge sword from our first crackling fires to the computer chip. But, as technology has become increasingly sophisticated the benefits of its and threats of its abuse have concomitantly grown. The Academies have released a report that now identifies actions, including deployment of available technologies, that can be taken immediately, and it points to the urgent need to initiate research and development activities in critical areas to prevent the USA, and putatively its allies from succumbing to terrorist attack.

Lewis Branscomb

Lewis Branscomb

The scientific and engineering community is aware that it can make a critical contribution to protecting the nation from catastrophic terrorism, said Lewis Branscomb, co-chair of the committee that wrote the report, and emeritus professor of the John F. Kennedy School of Government, at Harvard University, Cambridge, Massachusetts. Our report gives the government a blueprint for using current technologies and creating new capabilities to reduce the likelihood of terrorist attacks and the severity of their consequences.

The Academies’ report suggests that action can be taken now to protect and control nuclear weapons and radioactive material, to produce adequate vaccine and antibody supplies to combat biological weapons, to secure shipping containers and electric power grids, and to improve ventilation systems and emergency communications. The authors list literally dozens of specific recommendations for research and development activities that could lessen vulnerabilities to terrorism.

Richard Klausner

Richard Klausner

Biomedical research know-how, for instance, might be harnessed to develop drugs to fight pathogens for which there are currently no treatments. Electrical engineers could generate smart power grids and adaptive systems that can cope even when sections are sabotaged or seriously damaged.

Critically, the report points to the opportunity new computer programs provide in data-mining and scanning information to make it easier for the intelligence services to join the dots between seemingly unrelated snippets of information.

Research is also to be encouraged in the development of new emergency equipment, such as better protective gear for rescue workers and sensors to alert them to radiological or chemical contamination and other hazards when they enter a disaster area. These opportunities will go unrealised unless the government is able to establish and execute a coherent strategy for taking advantage of the nation’s scientific and technical capabilities, adds co-chair Richard Klausner (Gates Foundation team), Executive Director of the Global Health Program, at the Bill and Melinda Gates Foundation in Seattle. The federal agencies with science and engineering expertise are not necessarily the same as the agencies responsible for deploying systems to protect the nation, and they all must work together to discover and implement the best counter-terrorism technologies.

The report is aimed squarely at the US federal government, but many institutions from cities and states to private companies and universities will have to work together to discover and deploy anti-terrorism solutions.

It appears that it will hit home, Branscomb told Spotlight. At a hearing before the House Science Committee and the Senate subcommittee for Science, with some eighteen members present, both the senior senator (a democrat) and the senior congressman (a republican) endorsed the two key institutional recommendations. Since they are responsible for marking up that part of the Bill establishing the new department and dealing with science and technology it seems likely that the Academies’ study will influence the legislation that creates the department, he adds.

Making the Nation Safer: The Role of Science and Technology in Countering Terrorism will be available from the National Academy Press.

Further reading

Lewis Branscomb
http://belfercenter.ksg.harvard.edu/experts/125/lewis_m_branscomb.html

Bill and Melinda Gates Foundation
http://www.gatesfoundation.org/Pages/home.aspx

Making the Nation Safer: The Role of Science and Technology in Countering Terrorism
http://www.nap.edu/catalog.php?record_id=10415

Suggested searches

USA science policy

DNA and chips

The secret ingredient in a future biological computer is to add a little DNA. But, making hybrid devices from a silicon chip and a strand of genetic material means mixing hard-wired microelectronics technology with the softer world of molecular biology.

Now, chemists at the University of Newcastle upon Tyne have come up with a solution that could lead to new lab-on-a-chip devices and biological sensors for use in medicine and environmental analysis. It might even one day allow biology to compute or provide an interface between electronic devices and living things.

Ben Horrocks

Ben Horrocks

Newcastle chemists Benjamin Horrocks and Andrew Houlton and their colleagues have devised a way to automate the solid-phase synthesis of DNA on a semiconductor chip. They believe their method could readily be adapted to the conventional fabrication techniques of photolithography used in the microelectronics industry to pattern the microscopic transistors and circuitry on a computer chip.

The team recently reported how it has found a way to attach a DNA sequence of just seventeen nucleotides to a silicon surface modified with organic molecules. The key to unlocking hybrid DNA chips lies in the team’s use of bifunctional organic molecules. At one end the molecule has the right chemistry to allow it to be attached to an oxide-free silicon surface. The other end of the molecule has a functional chemical group on which a DNA strand can be grown using an automated DNA synthesizer of the kind found in biotech laboratories the world over.

Andrew Houlton

Andrew Houlton

The team is working with two aims in mind – first, the development of chemical sensors and secondly the synthesis of DNA on silicon surfaces for nanoscale molecular architecture. This addresses the projected reduction in the size of electronic components which by 2015 are predicted to be of the order of nanometres (i.e. built from molecules), explains Houlton.

Gel electrophoresis reveals DNA is attached to the silicon

Gel electrophoresis reveals DNA is attached to the silicon

Previous endeavours in this area have generally used glass in preference to silicon wafers and those that have focused on silicon have applied organic molecules to an oxidised surface rather than the naked silicon chip. The Newcastle team has now confirmed that it is possible to cover the surface of a silicon chip with DNA strands. Moreover, the 17-base DNA strands can be coupled with the complementary DNA strand making the familiar DNA double helix. From the nanodevice perspective the importance of the team’s work lies in their ability to pattern the surface of the silicon rather than simply randomly deposit DNA strands. Patterning using the printing and etching techniques of microelectronics fabrication means they can tightly control the arrangement of the DNA on the surface and so produce what might one day become molecular circuitry.

A DNA-patterned silicon surface

A DNA-patterned silicon surface

Sequential modification of a silicon surface with DNA

Sequential modification of a silicon surface with DNA

Further reading

Angew. Chem. Int. Ed., 41, 615 (2002)
http://www3.interscience.wiley.com/cgi-bin/abstract/90512278/ABSTRACT

DOI: 10.1002/1521-3773(20020215)41:4<615::AID-ANIE615>3.0.CO;2-Y

Benjamin Horrocks
http://www.ncl.ac.uk/chemistry/staff/profile/b.r.horrocks

Andrew Houlton
http://www.ncl.ac.uk/chemistry/staff/profile/andrew.houlton

Suggested searches

Molecular Electronics
Nanotechnology