GPS Could Speed Tsunami Warning

wwood_98 writes to tell us that Wired is running a story about how GPS could serve more than its traditional role. From the article: "International organizations like the Pacific Tsunami Warning Center, or PTWC, in Hawaii currently depend on coastal seismic stations to record deep-sea earthquakes that could cause giant waves. But according to Jeff Freymueller, a geophysicist at the University of Alaska Fairbanks, data from GPS receivers could provide quicker, more accurate estimates of the magnitude of a tsunami-causing quake, buying time for evacuation. Freymueller presented his findings at this week's American Geophysical Union conference in San Francisco."

Comments

Grade of GPS being used?

[Funakoshi]

Does anyone have any further information regarding what grade of GPS is being used? Based on the price point, I would have to guess that it is Mapping grade GPS equipment, but the problem would be that in order for Mapping grade GPS to update, the person (or mount) holding it, must be moving to get the corrections from the satellite. Survey grade may work, but it wouldn't be under $10k per receiver.

Any help?

A better use for GPS?

[thisjustin]

I think this article (and the researcher) missed the point of a far more profound, yet more far-off, use of GPS in earthquake detection. Spectrum recently ran a story describing how the GPS system among other things could sense impending earthquakes days, weeks, and even months in advance of an earthquake. The basic concept is the cracking of rocks in the crust leading up to an earthquake frees electrons which rush downward creating positvely charged holes. These holes also appear at Earth's surface and attract electons out of the ionosphere. The phase difference of the two signals the GPS satelites transmit is affected by this change and the change from normal values can be detected. This is still a long way off, and the use of GPS to measure this phenomena is only one and definitely not the best. But it sounds better than the couple hours mentioned in the article.

Other uses for these GPS measurement stations

[Reverse Gear]

Just wanted to add that these GPS measurement stations put up for this purpose could give valauable information that could also be used for other many purposes, I can mostly think of geophysics purposes as that is what I work with myself, but I imagine such a web could be used for many other things

I remember a paper about the isostatic rebound after the icecap in Scandinavia where GPS recievers were used. A curiosity I remember from the paper was that at the coastal areas there were quite a lot more uncertainty on the vertical movement, which the authors said probably was caused by the bigger amount of snow that assembles on the GPS devices and thereby causing refraction of the waves used for the GPS measurement

GPS information could is also used to determine the absolute movement of plates and I imagine that this system could also with time, be used to predict big earthquakes more precisely and thereby give even more time to prepare for the tsunamies etc.

But

[Catmeat]

More accurate seismometers would be nice. But one thing about sea-floor earthequakes is that some generate tsunamis and some do not. That's why NOAA spends a bucket-load of money maintaining a network of deep-ocean pressure sensors on the bed of the Pacific (link) These work because a tsunami in deep ocean has a wavelength vastly greater than the depth of water so it produces a small, but characteristic and detectable, pressure pulse as it passes over the sensor.

If this GPS idea works as advertised, it'll be a very useful incremental improvment to the tsunami warning networks. But it'll hardly be revolutionary. Being able to determine which events will produce a tsunami just from the seismic data - that would be revolutionary.