Attempts to forecast earthquakes sometimes get a chilly reception among scientists. Many such efforts have proved fruitless and, seismologists and geophysicists worry, could lead to exaggerated public expectations.
/ ORANGE COUNTY REGISTER
Published: Sept. 10, 2012 Updated: Oct. 5, 2012 2:35 p.m.
Attempts to forecast earthquakes sometimes get a chilly reception among scientists. Many such efforts have proved fruitless and, seismologists and geophysicists worry, could lead to exaggerated public expectations.
And the scientists at Chapman University are careful not to claim they are forecasting quakes.Still, in research they consider to be in the "validation" phase, Chapman scientists say their monitoring of two types of signals – radon emissions and heat signatures – have shown increased activity hours, days or weeks before several recent quakes.
The data are not unambiguous. Neither the timing nor the location of potential quakes can be nailed down precisely. False positives also have occurred on several occasions, when the signs of impending quakes were not followed by actual tremors.
But recent hits from Chapman's analysis method have come close enough, in some cases, to trigger internal alerts among the Chapman researchers, said Menas Kafatos, director of Chapman's Center of Excellence of Earth Systems Modeling and Observations.
His research group, which tracks trends and patterns in a variety of natural systems, including wind, weather and waves, uses both ground and satellite measurements to look for signs of coming quakes.
A sensor in a campus basement can pick up spikes in radon, a naturally occurring radioactive element that is released from the Earth's outer crust. The sensor was installed by another member of Kafatos' team, Dimitar Ouzounov.
And a campus antenna is used to gather data from satellites, including increased heat from points on the surface tracked by infrared emissions.
The radon data, Kafatos said, can provide a rough idea of how far away a coming quake might be, but cannot pinpoint where it will happen.
Radon readings also yield a rough idea of when a quake might occur, say within a matter of days.
The heat signatures, meanwhile, do a better job of localizing where a potential quake might happen. They can be seen days to weeks before a quake.
Not all quakes yield data from both sources, and interference can disrupt their forecasting potential.
With those cautions in mind, here is what the scientists can say about recent readings:
On Aug. 7, the radon sensor showed a "local anomaly" about 10 p.m. About an hour and a half later, a magnitude 4.5 quake occurred northeast of Yorba Linda. This reading was noted by the scientists after the quake, although instruments had picked it up before.
On Aug. 8, Kafatos said, the radon sensor picked up "continuous activity" indicating an active earthquake region.
On Aug. 9, a magnitude 4.4 quake occurred off Northern California. And a thermal signature had been seen in satellite data for the same region on Aug. 1.
On Aug. 10, readings from the radon sensor led to estimates of a magnitude 3.5 to 4 about 30 miles away. On August 11, the Channel Islands experienced a 3.4 quake.
Signs of the Aug. 11 event also triggered an internal alert among Chapman scientists.
Kafatos said he is not claiming to have forecast any of the quakes.
"The challenge is that we don't have a reliable system yet to do continuous monitoring; we cannot do forecasts. That would require a lot more manpower and resources," he said. "And we do have interference with nearby sources. We need more statistics."
Even with the uncertainties, however, advance indications of a large quake would present the scientists with a dilemma.
Should they alert public agencies, risking public distress and ridicule if they're wrong?
"If it's going to be a whopping signal, a 7.0 coming, then I would probably be talking to the authorities," he said.
Seismologist Lisa Grant Ludwig at UC Irvine, who previously worked at Chapman and has conducted research on numerical modeling of earthquakes that could be used in forecasting, said she is unfamiliar with the work being done at Chapman.
But she and Kafatos said scientists can react skeptically to any talk of earthquake prediction.
That became especially true, she said, after a flurry of interest in the 1970s and early 1980s.
"There was a period of time when the seismic community was very excited about earthquake prediction," she said. "A lot of people worked on it, and found it to be much more challenging than they expected. Then the 'prediction' word became kind of the 'P' word that we don't like to use."Source: http://www.ocregister.com/news/scientists-370907-chapman-quakes.html
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