SoylentNews is people
SoylentNews
Gravitational wave detectors could provide advance notice of seismic waves caused by powerful earthquakes (magnitude 8.5 and greater), allowing a little more time for people to evacuate (particularly at coastal regions that may be endangered by a tsunami):
Gravity signals that race through the ground at the speed of light could help seismologists get a better handle on the size of large, devastating quakes soon after they hit, a study suggests. The tiny changes in Earth's gravitational field, created when the ground shifts, arrive at seismic-monitoring stations well before seismic waves.
"The good thing we can do with these signals is have quick information on the magnitude of the quake," says Martin Vallée, a seismologist at the Paris Institute of Earth Physics.
Seismometers in China and South Korea picked up gravity signals immediately after the magnitude-9.1 Tohoku earthquake that devastated parts of Japan in 2011, Vallée and his colleagues report in Science on December 1. The signals appear as tiny accelerations on seismic-recording equipment, more than a minute before the seismic waves show up.
Observations and modeling of the elastogravity signals preceding direct seismic waves (DOI: 10.1126/science.aao0746) (DX)
Related: First Joint Detection of Gravitational Waves by LIGO and Virgo
The Nobel Physics Prize Has Been Awarded to 3 Scientists for Discoveries in Gravitational Waves
"Kilonova" Observed Using Gravitational Waves, Sparking Era of "Multimessenger Astrophysics"
(Score: 0) by Anonymous Coward on Wednesday December 06 2017, @02:57AM (2 children)
The way a seismograph is normally used is to detect seismic waves. The Tōhoku earthquake and the 2004 Indian Ocean earthquake both happened offshore, where it isn't convenient to place seismographs. Also, earthquakes often happen deep within the Earth's crust. Seismic waves travel at 2 to 8 km/s; it takes time for them to reach the detectors. Any warning that is available "before the seismic waves show up" is useful. People can shelter, start to leave tsunami-prone areas, begin shutting down refineries and nuclear plants, break trains, etc.
(Score: 1, Interesting) by Anonymous Coward on Wednesday December 06 2017, @04:31AM (1 child)
This caused the Fukushima disaster.
Power at the site arrives via: nuclear generation, emergency diesel, and power lines
Power at the site is needed for: running water pumps to prevent a meltdown
When you "shut down" the plant, it continues to generate enough heat for a meltdown but not enough to run the turbines for power generation. Restarting within the same day isn't a safe option due to Xenon in the fuel rods; it slows the reaction but suddenly gets lost if the temperature rises, causing the reaction to get out of control.
So as soon as you shut down, you come to depend on power from the power line and/or the emergency diesel. Both were wiped out by a tsunami. Had they not shut down, they could have just kept running.
(Score: 0) by Anonymous Coward on Thursday December 07 2017, @12:19AM
I was thinking of a loss-of-coolant accident (LOCA). A severe earthquake could cause a reactor vessel to crack. That may have happened at Fukushima Daiichi. A severe earthquake could also deform or dislodge reactor components so that the control rods could no longer be inserted (if I'm not mistaken, they were successfully inserted at Fukushima--and one reactor which melted down had been shut down days before the disaster). If you expect those things to happen, wouldn't you want to insert the control rods before the seismic waves arrive, to at least bring the reactor to a subcritical condition? Or perhaps, depending on the design, you could count on having a negative void coefficient so criticality would end as your coolant boiled off.
Instead of shutting down, another response to an early earthquake warning could be to attempt to start the backup generators.
Your suggestion to keep a reactor running normally during an earthquake is an interesting one, but it isn't commonly accepted, is it? I'm guessing that, had they done it at Fukushima, the result might have been one reactor (the one with the cracked reactor vessel) might have had a more severe melt-down, but the other two might have been saved.