Scientists may have discovered a breakthrough in earthquake prediction. Researchers studying the 9.1 magnitude Tohoku quake in Japan from 2011, have found that gravity signals were detected in real time and before the seismic waves appeared
LOS ANGELES, CA (California Network) – Earthquakes are caused by sudden movements in the Earth’s crust, usually deep below the surface. These movements can disturb the Earth’s gravitational field. The disturbances are minuscule but detectable, and they move at the speed of light making them detectable in real time. In other words, scientists can detect these signals as soon as the quake begins and before seismic waves appear at the surface.
The time between the gravity signals and the seismic wave appearing is quite small, perhaps only a second, but they provide valuable information. For example, the gravity signals can be used to accurately assess the magnitude of a quake the instant movement stops.
Presently, initial magnitudes are best guesses and they are quickly revised as data becomes available to seismologists. However, data can trickle in and magnitudes can be revised up to several hours after an event. And the difference between a 9.0 event and a 9.1 is quite large, with the 9.1 event being about 40 percent stronger than the 9.0.
This has ramifications for tsunami prediction. While quakes kill thousands, tsunamis have the potential to kill many times more people. During a quake, people can take shelter or run outside. However, a tsunami is virtually impossible to escape once it hits. Knowing how bad it will be is essential to warning people and getting them to safety.
By measuring the gravity signals, scientists think they can develop a method to accurately predict tsunami size within minutes. That will allow them to provide a more precise warning and enable emergency planners to order an appropriate response without wasting resources.
Presently, tsunami prediction is still educated guesswork based on patchwork data involving seismographs, satellites, and sensor buoys.
Unfortunately, gravity signals don’t emerge before the quake starts, so the signals can’t be used for genuine quake prediction, but they could be used in the future to further enhance early warning signals which can provide people with precious seconds to seek cover in the event of a major quake.