Source of mystery booms likely to remain unknown
- Source of mystery booms likely to remain unknown
'Quiet' N.C. has no seismic-detection network
By Paul Garber
The mysterious booms that rocked much of downtown Saturday night may remain forever a mystery.
About 8:20 p.m., 911 dispatchers started getting a wave of calls reporting the booms, said Shawn Cline, the hazardous-materials coordinator for the Winston-Salem/Forsyth County Office of Emergency Management. The calls covered an area of downtown between Glade and Cherry streets, from Brookstown Avenue to the south and West 24th Street to the north, he said.
Cline said that he spent most of yesterday looking at whether a small earthquake or sonic boom might have caused the noise, but by the end of the day he didn't have a solid answer.
There may not be enough earthquake-measuring equipment in the area to determine whether a small earthquake occurred, said Tyler Clark, the chief geologist for the N.C. Geological Survey.
"This is likely to go down in the history books as a mystery," Clark said.
Saturday's booms were about the 10th such report he has had from the Winston-Salem area in the past five years, Clark said.
"These are not anything new," he said. "They've happened to our state for a long time."
There are more active fault lines in the states that border North Carolina then there are inside the state, he said.
"In North Carolina, we sit in the quiet zone," he said. Because of that, there is not a network of seismic equipment to track local earthquakes. It would be too expensive to track activity that almost never causes death or destruction here, he said.
It's also possible that the noise was a sonic boom, which is more likely to make the kind of explosive sound reported than an earthquake, Clark said.
But a sonic boom could not have come from a plane leaving or landing at Smith Reynolds Airport because the plane would be going too slow, said Dave Short, the air traffic manager at the airport.
Sonic booms occur when an airplane goes faster than the speed of sound.
Smith Reynolds air-traffic controllers do not track anything above its air space of 12,000 feet, Short said.
City public utilities officials considered the possibility that a methane explosion in a nearby sewer could have caused the booms but have ruled out that possibility.
"If an explosion had happened, there's got to be a release of pressure somewhere," said Ron Hargrove, the deputy director for the City-County Utilities Division. There have been no such reports, which would include such things as blown manhole covers or bubbles in toilet water.
Loud noises and vibrations that struck the Konnoak Hills neighborhood in 1994 turned out to be small earthquakes, the largest of which measured 1.7 on the Richter scale.
• Paul Garber can be reached at 727-7302 or at pgarber@...