Dryden sonic boom researcher Ed Haering answers questions on NASA sonic boom research during a Jan. 25 NASA.gov Web chat. At right is Gray Creech from Dryden public affairs. (NASA Photo / Tom Tschida) › View Larger Image Dryden Helps Determine Whether Sonic Booms Will Create False Alarms
Dryden and Seismic Warning Systems Inc., Scotts Valley, Calif., are evaluating the company's QuakeGuard earthquake warning system to determine whether sonic booms cause the system to register false alarms.
Under a NASA Space Act agreement, the company has installed two of their QuakeGuard warning seismometers at Dryden. With the system in test mode, not warning mode, devices were installed in Dryden's main office building, spaced about 100 feet apart and tied into the building's foundation. Vertical accelerometers in the devices, using the company's proprietary algorithms, are designed to detect precursor, or "P," waves that travel ahead of the primary, destructive "S" shockwaves generated by earthquakes.
Dryden's Innovative Partnership Program Office, which is now known as the Innovative Partnerships Office, helped establish the Space Act Agreement that is the foundation for the partnership. In addition, the IPO Office and NASA's Airborne Sciences program funded the purchased of seismometers.
Also as part of the Space Act Agreement, Seismic Warning Systems loaned Dryden additional seisometers for the flight research.
So far, normal sonic booms are not causing the system to generate false alarms. But Dryden, in an effort dubbed SonicBREWS, or Sonic Boom Resistant Earthquake Warning System, put the system to the test with three flights during which an F/A-18 aircraft made sharp dives to generate sonic boom shockwaves directly on the building, thereby better mimicking the P waves.
The UAVSAR aboard NASA's Gulfstream III research aircraft captured this interferogram of the magnitude-7.2 Baja California earthquake that struck on April 4, 2010. The interferogram is overlaid atop a Google Earth image of California's Coachella Valley-Salton Sea region. (NASA/JPL/USGS/Google) › View Larger Image Such a system is currently in operation in California's Coachella Valley, with warning devices installed in several schools and fire stations. The system worked during one of California's most recently felt quakes, the 7.2-magnitude Baja California earthquake that occurred April 4, 2010, the strongest in the region in 18 years. The earthquake was larger than the devastating 7.0 Haitian earthquake of last January.
The QuakeGuard system successfully detected the Baja quake's P wave 90 seconds before arrival of the S waves and set off alarms that included the automatic raising of local fire station doors, which are integrated into the system. During earthquakes, fire station doors are frequently jammed shut, interfering with local fire department response.
Depending on the geographic distance from an earthquake epicenter, officials estimate such warning systems could provide up to five minutes warning prior to the arrival of a distant quake, but only seconds ahead for a device located near the epicenter. Though 90 seconds may sound like little warning, that much time or less is enough to allow people to take shelter, for automated valves on gas company pipes to shut gas off and for fire station doors to open.
Plans are being developed for installation of such a system in the Lancaster-Palmdale area, which lies adjacent to the San Andreas Fault about 70 miles northeast of Los Angeles. Due to the frequency of sonic booms in the area from flight test aircraft operating out of Edwards Air Force Base, Seismic Warning Systems must determine whether sonic booms need to be filtered out of the system.
Additionally, Dryden is working with the company on a white-paper study of the technology and the effects of sonic booms, or lack thereof, on its capabilities.