Seismometers could not accurately tell the source of a tremor, whether it was a natural earthquake or a nuclear explosion. So, researchers tried to find a new approach and devised a new tool that could distinguish the two accurately.
New Tool Could Determine Earthquakes From Nuclear Explosions Accurately
Various techniques have been developed over the past 60 years to help hunt for underground tests. Analyzing the source's depth or position is one of the easiest. An occurrence could be viewed with greater suspicion if it occurs distant from plate tectonic boundaries and volcanoes. Alternatively, it is unlikely to have been a nuclear test if it happened at a depth of more than three kilometers.
These straightforward techniques aren't infallible, though. For example, tests for camouflage may be conducted in earthquake-prone locations; shallow earthquakes may also occur.
Calculating the ratio of energy conveyed in surface waves to energy transferred in body waves is a more advanced monitoring technique. Compared to explosions, earthquakes often release a greater amount of energy as surface waves.
Though it is also not perfect, this approach has shown to be very successful at locating underground nuclear experiments. Because the 2017 North Korean nuclear test was conducted inside a tunnel situated inside a mountain, it was unable to categorize it adequately, even though it caused significant surface waves.
Researchers from Los Alamos National Laboratory in the US and the Australian National University collaborated to reevaluate the issue of identifying the source of seismic waves. They used a more sophisticated statistical model with a recently established method to depict the displacement of rocks at the epicenter of a seismic event and explain various occurrences.
Because of the essential distinctions between the causes of earthquakes and explosions, they created a more accurate system for categorizing these occurrences.
Using databases of known explosions and earthquakes from the western United States, they evaluated their strategy and found that it was accurate approximately 99 percent of the time. This makes it a valuable new instrument in the fight against covert nuclear testing.
Global monitoring efforts will continue to depend heavily on reliable methods for identifying nuclear tests. They play a crucial role in making sure that governments are held responsible for the effects that nuclear weapons testing has on the environment and society.
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Can Nuclear Explosion Cause Earthquake?
An earthquake and maybe an aftershock sequence can result from a nuclear explosion. On the other hand, explosion-induced earthquakes have been far more minor than the explosion itself, and the aftershock series produces smaller aftershocks relative to an earthquake of comparable strength.
Not every explosion has resulted in an earthquake. An earthquake that an explosion could cause would only be able to occur a few tens of kilometers away from the shot location.
In 1969, it was publicly discussed that massive nuclear explosions at the Nevada Test Site would cause catastrophic earthquakes in California. Plotting the frequency of large-magnitude earthquakes in northern California (1965-1969) against the known times of the six biggest thermonuclear tests (1965-1969) tested this theory, and the results clearly showed no seismicity peaks at the explosion times.
The largest U.S. underground thermonuclear tests were detonated at Amchitka, on the western extremity of the Aleutian Islands. The biggest of these was a test of five megatons, known as Cannikin, which released energy equivalent to a magnitude 6.9 earthquake on Nov. 6, 1971. Nothing seismic occurred in the seismically active area of the Aleutian Islands.
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