NASA Tests GPS Monitoring System for Big U.S. Earthquakes

The space-based technology that lets GPS-equipped motorists constantly update their precise location will undergo a major test of its ability to rapidly pinpoint the location and magnitude of strong earthquakes across the western United States.

Results from the new Real-time Earthquake Analysis for Disaster (READI) Mitigation Network soon could be used to assist prompt disaster response and more accurate tsunami warnings.

The new research network builds on decades of technology development supported by the National Science Foundation, the Department of Defense, NASA, and the U.S. Geological Survey (USGS). The network uses real-time GPS measurements from nearly 500 stations throughout California, Oregon and Washington. When a large earthquake is detected, GPS data are used to automatically calculate its vital characteristics including location, magnitude and details about the fault rupture.

"With the READI network we are enabling continued development of real-time GPS technologies to advance national and international early warning disaster systems," said Craig Dobson, natural hazards program manager in the Earth Science Division at NASA Headquarters in Washington. "This prototype system is a significant step towards realizing the goal of providing Pacific basin-wide natural hazards capability around the Pacific 'Ring of Fire.'"

Accurate and rapid identification of earthquakes of magnitude 6.0 and stronger is critical for disaster response and mitigation efforts, especially for tsunamis. Calculating the strength of a tsunami requires detailed knowledge of the size of the earthquake and associated ground movements. Acquiring this type of data for very large earthquakes is a challenge for traditional seismological instruments that measure ground shaking.

High-precision, second-by-second measurements of ground displacements using GPS have been shown to reduce the time needed to characterize large earthquakes and to increase the accuracy of subsequent tsunami predictions. After the capabilities of the network have been fully demonstrated, it is intended to be used by appropriate natural hazard monitoring agencies. USGS and the National Oceanic and Atmospheric Administration are responsible for detecting and issuing warnings on earthquakes and tsunamis, respectively.

"By using GPS to measure ground deformation from large earthquakes, we can reduce the time needed to locate and characterize the damage from large seismic events to several minutes," said Yehuda Bock, director of Scripps Institution of Oceanography's Orbit and Permanent Array Center in La Jolla, Calif. "We now are poised to fully test the prototype system this year."

The READI network is a collaboration of many institutions including Scripps at the University of California in San Diego; Central Washington University in Ellensburg; the University of Nevada in Reno; California Institute of Technology/Jet Propulsion Laboratory (JPL) in Pasadena; UNAVCO in Boulder, Colo.; and the University of California at Berkeley.

NASA, NSF, USGS, and other federal, state, and local partners support the GPS stations in the network, including the EarthScope Plate Boundary Observatory, the Pacific Northwest Geodetic Array, the Bay Area Regional Deformation Array and the California Real-Time Network.

"The relatively small investments in GPS-based natural hazards systems have revolutionized the way we view the Earth and allowed us to develop this prototype system with great potential benefits for the infrastructure and population in earthquake-prone states in the western United States," said Frank Webb, Earth Science Advanced Mission Concepts program manager at JPL.

The READI network is the outgrowth of nearly 25 years of U.S. government research efforts to develop the capabilities and applications of GPS technology. The GPS satellite system was created by the Department of Defense for military and ultimately civil positioning needs. NASA leveraged this investment by supporting development of a global GPS signal receiving network to improve the accuracy and utility of GPS positioning information. Today that capability provides real-time, pinpoint positioning and timing for a wide variety of uses from agriculture to Earth exploration.

"Conventional seismic networks have consistently struggled to rapidly identify the true size of great earthquakes during the last decade,"

said Timothy Melbourne, director of the Central Washington University's Pacific Northwest Geodetic Array. "This GPS system is more likely to provide accurate and rapid estimates of the location and amount of fault slip to fire, utility, medical and other first-response teams."

The GPS earthquake detection capability was first demonstrated by NASA-supported research on a major 2004 Sumatra quake conducted by Geoffrey Blewitt and colleagues at the University of Nevada in Reno.

NASA, NOAA Data Show Significant Antarctic Ozone Hole Remains

 NASA, NOAA Data Show Significant Antarctic Ozone Hole

The Antarctic ozone hole, which yawns wide every Southern Hemisphere spring, reached its annual peak on Sept. 12. It stretched to 10.05 million square miles, the ninth largest ozone hole on record. Above the South Pole, the ozone hole reached its deepest point of the season on Oct. 9, tying this year for the 10th lowest in this 26-year record. 

NASA and the National Oceanic and Atmospheric Administration (NOAA) use balloon-borne instruments, ground-based instruments and satellites to monitor the annual Antarctic ozone hole, global levels of ozone in the stratosphere and the manmade chemicals that contribute to ozone depletion. 

"The colder than average temperatures in the stratosphere this year caused a larger than average ozone hole," said Paul Newman, chief scientist for atmospheres at NASA's Goddard Space Flight Center in Greenbelt, Md. "Even though it was relatively large, the area of this year's ozone hole was within the range we'd expect given the levels of manmade ozone-depleting chemicals that continue to persist in the atmosphere." 

The ozone layer helps protect the planet's surface from harmful ultraviolet radiation. Ozone depletion results in more incoming radiation that can hit the surface, elevating the risk of skin cancer and other harmful effects.

"The manmade chemicals known to destroy ozone are slowly declining because of international action, but there are still large amounts of these chemicals doing damage," said James Butler, director of NOAA's Global Monitoring Division in Boulder, Colo. 

In the Antarctic spring (August and September) the sun begins rising again after several months of darkness and polar-circling winds keep cold air trapped above the continent. Sunlight-sparked reactions involving ice clouds and manmade chemicals begin eating away at the ozone. Most years, the conditions for ozone depletion ease before early December when the seasonal hole closes. 

Levels of most ozone-depleting chemicals in the atmosphere have been gradually declining as the result of the 1987 Montreal Protocol, an international treaty to protect the ozone layer. That international treaty caused the phase-out of ozone-depleting chemicals, which had been used widely in refrigeration, as solvents and in aerosol spray cans. 

However, most of those chemicals remain in the atmosphere for decades.

Global atmospheric computer models predict that stratospheric ozone could recover by midcentury, but the ozone hole in the Antarctic will likely persist one to two decades longer, according to the latest analysis in the 2010 Quadrennial Ozone Assessment issued by the World Meteorological Organization and United Nations Environment Programme, with co-authors from NASA and NOAA. 

NASA currently measures ozone in the stratosphere with the Dutch-Finnish Ozone Monitoring Instrument, or OMI, on board the Aura satellite. OMI continues a NASA legacy of monitoring the ozone layer from space that dates back to 1972 with launch of the Nimbus-4 satellite. The instrument measured the 2011 ozone hole at its deepest at 95 Dobson units on Oct. 8 this year. This differs slightly from NOAA's balloon-borne ozone observations from the South Pole (102 Dobson units) because OMI measures ozone across the entire Antarctic region. 

That satellite-monitoring legacy will continue with the launch of NASA's National Polar-orbiting Operational Environmental Satellite System Preparatory Project, known as NPP, on Oct. 28. The satellite will carry a new ozone-monitoring instrument, the Ozone Mapping and Profiler Suite. The instruments will provide more detailed daily, global ozone measurements than ever before to continue observing the ozone layer's gradual recovery. 

It will take a few years of averaging yearly lows in Antarctic ozone to discern evidence of recovery in ozone levels because seasonal cycles and other variable natural factors -- from the temperature of the atmosphere to the stability of atmospheric layers -- can make ozone levels dip and soar from day to day and year to year. 

NOAA has been tracking ozone depletion around the globe, including the South Pole, from several perspectives. NOAA researchers have used balloons to loft instruments 18 miles into the atmosphere for more than 24 years to collect detailed profiles of ozone levels from the surface up. NOAA also tracks ozone with ground-based instruments and from space. 

For the updates on the status of the Antarctic ozone layer, visit: http://ozonewatch.gsfc.nasa.gov

For more information on the Antarctic ozone hole, visit: http://www.ozonelayer.noaa.gov