Scientists devise technology that can distinguish mine collapses from other seismic activities

July 14th, 2008 - 2:21 pm ICT by ANI  

Washington, July 14 (ANI): Scientists have developed a method to detect underground nuclear weapons tests to quickly examine the seismic recordings of the event and determine whether that source was most likely from mine collapses or from other seismic activities.

Lawrence Livermore National Laboratory scientists and colleagues from the Berkeley Seismological Laboratory at UC Berkeley developed the method.

They also found an additional string of secondary surface seismic waves that occurred when the mine collapsed, which are like no other mine collapse events in recent history.

The collapse of a Utah coal mine on August 6th resulted in the deaths of six miners. Ten days later, another collapse killed three rescue workers.

The event was recorded on the local network of seismic stations operated by the US Geological Survey as well as the National Science Foundation Earthscope US Array stations. The collapse registered as a 3.9 magnitude event.

Our group had already been working on a full seismic waveform matching technique as a means to distinguish between nuclear explosions, earthquakes and collapse events by their seismic signals, said Bill Walter, one of the LLNL researchers.

The new study could help researchers better differentiate underground nuclear tests from earthquakes, mine collapses, mine blasts and other events that generate seismic waves.

UC Berkeley graduate student and LLNL Lawrence Scholar Sean Ford was able to quickly collect the data from the Crandall Canyon seismograms at the time and plug it into the Laboratory algorithm that pointed to a collapse rather than an earthquake.

These results were posted within a few days after the event and were helpful in resolving the source of the magnitude 3.9 seismic signal, said Ford.

The new technique compares model seismograms to the observed seismograms at local to regional distances (0-1,500 kilometers) at intermediate periods (five to 50 seconds).

According to Ford, the Crandall Canyon event was relatively small, magnitude wise.

The fact that we could identify the Crandall Canyon event from its seismic signature gives us confidence that it would be possible to identify even relatively small nuclear explosions using this technique, he said.

We are excited about the potential of this regional seismic full waveform matching technique and are continuing to develop and test it on other events in others parts of the world to fully understand it, said Walter. (ANI)

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