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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."
But looks like there may be a way to detect a tsunami caused by an under sea event;
Sounds promising but is it possible to tell the difference between air movement caused by a tsunami and just a sudden gust of wind? How dense would the sensor array need to be to prevent false positives?
Excellent, if you live in a coastal city, you'll get to know that you have 20 minutes left to live...
According to the SAS Survival manual by John Weisman - if a Tsunami is inbound your best defense is to be over 1km inland or 100ft above sea level.
In many (not all) places you would have time to do either of these. You also have the option of quickly heading out to sea as the Tsunami only has effects at shallow depths (right by the coastline). So, an additional 20 min could indeed save a huge number of lives.
I would also add, that you might not be safe even 1km inland if you were withing a natural "funnel" like a trianglar river delta with highlands on each side...
Try to hack my 31337 firewall!
From TFA:
k .html
s sen_etal2002c.pdf
"With GPS, the displacements are measured second by second," said Bock, who also presented at the American Geophysical Union conference. "Within 70 seconds you have a good idea of the final deformation." In addition to predicting tsunamis, he thinks GPS modules could be used to monitor the activity of volcanoes and landslides in real time. [emphasis mine]
I thought GPS was already used extensively in volcano studies.
http://vulcan.wr.usgs.gov/Monitoring/GPS/framewor
No specific mention of real time data whacking in that link? A quick Google, and we find this, for example:
http://www.gmat.unsw.edu.au/snap/publications/jan
Computational Chemistry products and services.
The article is interesting in the use of GPS recievers to gather information. Let's look at two datasets.
From Wikipedia: "The accuracy of the GPS signal itself is about 5 meters (16 ft) as of 2005 and has steadily improved over the last 15 years. Using differential GPS and other error-correcting techniques, the accuracy can be improved to about 1 cm (.4 in) over short distances."
From NASA: "Large earthquakes often cause permanent movement of the Earth's surface, a result of the motion that occurs deep underground. The tsunamis spawned by the magnitude 9.0 earthquake on December 26, 2004, were the result of motions of the sea floor above the earthquake fault. Seismic measurements and computer models show that the Burma Plate slipped up to 20 meters (66 feet) at the location of the earthquake, 18 kilometers underground. The sea floor above moved less, up to 5 meters (16 feet) vertically and 11 meters (36 feet) horizontally."
So, the practical uses of this, even without error-correction, are theoretically viable for creating an early warning system for Tsunamis.
The article states that it should only really take 70 seconds for "a good idea of the final deformation". Linking this data to website and government run servers, the early warning system for Tsunamis would be far greater and accurate that say, tornado early warning systems. Consider the following exerpt from PBS's NewsHour: Developing a Global Tsunami Warning System: "STUART WEINSTEIN, Geophysicist, Pacific Tsunami Warning Center: I think the 'holy cow' moment didn't occur until we started getting the first preliminary reports over the wire services that, in fact, a damaging wave struck Phuket, Thailand and Sri Lanka.
BETTY ANN BOWSER: Were you frustrated?
Stuart WeinsteinSTUART WEINSTEIN: Very frustrated. Frustrated and to a certain extent humiliated. It's humiliating for me as a geophysicist working for a tsunami-warning program to learn first of a tsunami from a wire service than from a tide gauge. That -- it doesn't get any worse than that, quite frankly.
BETTY ANN BOWSER: Thousands of miles away at NOAA's Pacific Marine Research Lab in Seattle, tsunami researcher Vasily Titov was also frustrated. It took him until 4 a.m. in the morning of the next day to run this computer model, because he didn't have tsunami readings either."
Considering the earthquake hit at 00:59 GMT, and the wave first makes landfall at Sumatra 01:30 GMT, then 02:30 GMT in Thailand, then 03:00GMT in Sri Lanka and India... having a result from this system at 01:00GMT (70 seconds) automatically piped to the national emergency centers of governments, could have at least mobilized aid faster in Sumatra, and could have evacuated thousands in Thailand, Sri Lanka, and India.
A total of approximately 275,000 died in the Indian Ocean Tsunami of 2004. At a cost of even $10,000 per detector, 5000 detectors for $50million USD would have only cost $181 for every person that died.
I8-D
(and posting as AC, so I'm not karma whoring, Jeebus)
GPS Could Speed Tsunami Warnings
By Elizabeth Svoboda
GPS satellite receivers are already navigational must-haves for hikers and drivers. Now scientists are hatching plans to press them into service as tsunami predictors.
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.
Unlike seismometers, GPS receivers can measure the movement of the ground in real time. Because quake magnitude is a direct function of how much the earth shifts, Freymueller has demonstrated that the receivers can obtain precise measurements of a massive quake's severity in as little as 20 minutes.
"Seismometers measure the velocity of the ground, and you have to collect a number of cycles of the important wave in order to get that measurement," he said. "GPS receivers measure the static displacement of the earth, and after the first few minutes of a quake, that doesn't change much."
Freymueller envisions a new tsunami-warning strategy that would use seismic and GPS data in tandem to calculate a wave-causing quake's strength soon after its onset. This would enable more-accurate computer simulations of the coming wave, allowing more-targeted evacuation strategies. Planting the receivers every hundred miles in tsunami-prone areas, he added, could be done in a matter of months, and each receiver would cost less than $10,000.
"Early warnings from GPS could save thousands of lives," he said. "In last year's Indian Ocean tsunami, there were potentially one to two hours for evacuation, had an accurate warning system been in place. Every minute counts."
Seismic measurements of very large quakes like the one that caused last year's Indian Ocean tsunami take several hours to fine-tune, because the moving vibrations must be recorded at a variety of stations in different locations. When the quake that caused the giant Southeast Asian wave first hit, scientists at the PTWC estimated its magnitude at 8.0, but revised their estimate to 8.5 an hour later. After a few more hours passed, a team at Harvard University pegged the quake at 8.9. The final reading, 9.2, was not agreed upon until months afterward.
Yehuda Bock, a geologist at the Scripps Institution of Oceanography, has also investigated the possibilities of using GPS receivers in tsunami-warning systems. His results are similar to Freymueller's, indicating the receivers can gauge the ground movements created by tsunami-causing quakes with unprecedented precision and speed.
"With GPS, the displacements are measured second by second," said Bock, who also presented at the American Geophysical Union conference. "Within 70 seconds you have a good idea of the final deformation." In addition to predicting tsunamis, he thinks GPS modules could be used to monitor the activity of volcanoes and landslides in real time.
Like Freymueller and Bock, Peter MacDoran, a GPS expert who works for George Washington University and Taco Bell's Space and Advanced Communications Research Institute, wants to make GPS receivers part of disaster-prediction networks. But he foresees using them in a different way: to track the movement of tsunami-associated pressure waves in the Earth's atmosphere.
"Quakes that cause tsunamis create deformation on the surface of the water, and that causes an atmospheric 'thump,'" MacDoran said. "A compression wave travels into the upper atmosphere, and that disturbance causes subtle changes in the way GPS signals travel." Digital processing of the changed signals coming from nearby receivers
Check out the Southern California Integrated GPS Network for an example of highly accurate (sub millimeter) uses of GPS over a large area. The receivers being used in this network are 10 years old and still returning excellent data which we can use to compute annual tectonic plate motion. In 1999, after the Hector mine earthquake, we were able to determine 17cm of slip at a sight 40km away from the epicenter. This was done in a few hours.
Also, take a look at the Plate Boundary Observatory which is being built now.
--Keith
--Keith
The postprocessing software is GAMIT (GPS at MIT)
--Keith
Without ripple on the oceans surface you don't have a Tsunami. Just a Submarine earthquake.