The World's Ears and Nose: This Monitoring System Detects Nuclear Threats

Acting as the Earth's global ears and nose, the Preparatory Commission for the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) collects data on everything from earthquakes in Nepal, North Korean nuclear missile tests, and the sounds of migrating sea creatures. And though you might not know about it, it's also there to safeguard the world from the next nuclear explosion.

At a conference next week in the Hofburg Palace in Vienna, researchers will be gathering to share knowledge on how the the data amassed by the centre can be used. The CTBTO's applications now go far beyond the founders' initial aims of banning nuclear explosions on Earth.

CTBTO is an independent international organisation established in 1996, which has agreed to cooperate with the UN since 2000. So far 183 countries have signed the treaty. The organisation draws data from a global monitoring network of 300 stations that detect nuclear explosions and make it harder for countries without nuclear bombs to develop them. It currently also helps scientists, governments and non-governmental organisations provide more precise information about climate change; helps tsunami warning centres issue rapid warnings after earthquakes; and improves systems that warn pilots about damaging volcano ash in real-time, just to name a few examples.

"The CTBTO's International Monitoring System has found a wider mission than its creators ever foresaw: monitoring an active and evolving Earth," said Lassina Zerbo, the executive secretary of CTBTO in a press statement. "Some compare the system to a combined giant Earth stethoscope and sniffer that looks, listens, feels and sniffs for planetary irregularities."

"When the centre was first established there was a realisation that many of the sciences and technologies for nuclear test verification were rather young. Seismology was probably the most mature of the technologies and infrasound (listening to the atmosphere to hear the low frequency blast waves) was perhaps the least understood," said the director of CTBTO, Randy Bell, over the phone.

"We have all these global infrasound systems listening to the sounds in the air, much like a global ear. We're also listening to the sounds underwater with microphones so you could call that an 'underwater ear'," he said.

Bell explained how the tech deployed by the centre had developed over the years, citing infrasound tech as one example."People have looked at our ability to listen to low frequency sound waves to understand the structure of the atmosphere," said Bell. He explained that measuring the propagation of sound allows the meteorological and climate science community to understand the temperature and density of the atmosphere, and come up with better weather forecasts. This is an example of how CTBTO's data is being used in applications beyond what is was originally intended for.

As for the "global nose", Bell pointed to CTBTO's plan for stations across the globe that "suck up air all day long through a filter paper" and help scientists work out what radioactive isotopes have been in the air around the station for that day. Back in 2011, the CTBTO system's atmospheric sampling tracked invisible radioactive plumes from the March 2011 Fukushima Daiichi nuclear power plant disaster spreading across the world. This helped officials determine that radioactivity levels were below dangerous levels outside of Japan.

So far, the international monitoring system has been indispensable. "The monitoring network detected all three of the declared North Korean nuclear tests well before the North Koreans officially announced that they had conducted nuclear tests," said Bell. "Our member states used the data to ascertain the nature of the event and made declarations of concern and condemned the test based on data from the system."

The CTBTO does not interpret or analyse the data, but supplies it to researchers, governments and NGOs. "What may be noise to me is probably valuable signal to [scientists]," said Bell. "If they create specialised algorithms to isolate and extract what is signal to them from my data stream, it helps me look deeper into my data to find what is of interest to the nuclear test monitoring community."