[Rockhounds] Gravity signals could detect earthquakes at the speed of light

[Dora Smith]

Does that give me an extra 1/10 of a second to dive under my desk?

Dora Smith

On 5/12/22 8:26 AM, Kreigh Tomaszewski wrote:
> Two minutes after the world’s biggest tectonic plate shuddered off the
> coast of Japan, the country’s meteorological agency issued its final
> warning to about 50 million residents: A magnitude 8.1 earthquake had
> generated a tsunami that was headed for shore. But it wasn’t until hours
> after the waves arrived that experts gauged the true size of the 11 March
> 2011 Tohoku quake. Ultimately, it rang in at a magnitude 9—releasing more
> than 22 times the energy experts predicted and leaving at least 18,000
> dead, some in areas that never received the alert. Now, scientists have
> found a way to get more accurate size estimates faster, by using computer
> algorithms to identify the wake from gravitational waves that shoot from
> the fault at the speed of light.
>
> “This is a completely new [way to recognize] large-magnitude earthquakes,”
> says Richard Allen, a seismologist at the University of California,
> Berkeley, who was not involved in the study. “If we were to implement this
> algorithm, we’d have that much more confidence that this is a really big
> earthquake, and we could push that alert out over a much larger area
> sooner.”
>
> Scientists typically detect earthquakes by monitoring ground vibrations, or
> seismic waves, with devices called seismometers. The amount of advance
> warning they can provide depends on distance between the earthquake and the
> seismometers, and the speed of the seismic waves, which travel less than 6
> kilometers per second. Networks in Japan, Mexico, and California provide
> seconds or even minutes of advance warning
> <https://www.science.org/doi/10.1126/science.362.6414.514>, and the
> approach works well for relatively small temblors. But beyond magnitude 7,
> the earthquake waves can saturate seismometers. This makes the most
> destructive earthquakes, like Japan’s Tohoku quake, the most challenging to
> identify, Allen says.
>
> Recently, researchers involved in the hunt for gravitational waves—ripples
> in space-time
> <https://www.science.org/content/article/ripples-spacetime-sciences-2016-breakthrough-year>
> created
> by the movement of massive objects—realized that those gravity signals,
> traveling at the speed of light, might also be used to monitor earthquakes.
> “The idea is that as soon as mass moves anywhere, the gravitational field
> changes, and … everything feels it,” says Bernard Whiting, a physicist at
> the University of Florida who worked on the Laser Interferometer
> Gravitational-Wave Observatory. “What was amazing was that the signal would
> be present even in seismometers.”
> https://www.science.org/content/article/gravity-signals-could-detect-earthquakes-speed-light
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