'I thought it was thunder,' one El Dorado County resident reportedly said, while another postulated, 'It's definitely not thunder; too consistent. I thought it was just mining.'
© Associated NewspapersUnsolved mystery: For years now, a series of loud, floor-rattling booms have shaken the floorboards and eardrums of El Dorado County, Calif. residents
'You can feel it in the ground, no question about it. But no one's been able to figure out why,' Peter O'Grady reportedly added. 'I tend to hear somewhere between four to six of these things during the weekdays usually between 11 p.m. and 2 p.m.'
'I always considered them to be sonic booms from flying aircrafts for years,' Loring Brunius told CBS13 in Sacramento, which decided to try to get to the bottom of the mystery.
The ambitious T.V. station interviewed people connected to many of the alleged causes of the sounds - mining quarries, a nearby naval station, and even local wineries - but couldn't get to the bottom of the oddity.
Brunius, who owns Sierra Rock and Diamond Quarry, said his company hasn't blasted since last year, ruling them out as the genesis of the weird - and some say - preternatural sounds.
"It's a federally mandated system, and enforced," Brunius reportedly explained.
The station found that some think the booms originate from nearby wineries using propane cannons to scare away birds. But a reporter foiled that hypotheses, as Carrie Bendick, a winemaker at Holly's Hill Winery reportedly said, 'We've never done it and I don't know of any other winery that does."
Determined to find the cause of the sounds, CBS13 also spoke to Fallon Naval Air Station. However, an official there reportedly said any supersonic flight operations are only allowed over Dixie Valley, which is hundreds of miles away.
Some think illegal mining could be the source of the sounds, CBS13 said, but Brunius doubts that theory. He told the station if that was the case, the culprit would have been caught by now.
According to U.S. Geological Survey, there aren't enough seismic stations to pinpoint the exact location of the sounds. And CBS13 reports that the rolling foothills of El Dorado County make it difficult for residents to even tell from what direction the sounds are coming.
Meanwhile, some say the booms have been around so long and happen so often they barely notice them anymore. Still, others want to solve the mystery.
'I would like to know what it is, yeah. And I'd like to know when it's going to stop, too,' a disgruntled O'Grady told CBS13.
They're just ordinary hail cannons boys an' girls.
A hail cannon is a shock wave generator claimed to disrupt the formation of hailstones in the atmosphere.
From Wikipedia:
These devices frequently engender conflict between farmers and neighbors when used because they are repeatedly fired every 1 to 10 seconds while a storm is approaching and until it has passed through the area, yet there is little or no scientific evidence for their effectiveness.
In a modern hail cannon an explosive charge of acetylene gas and air is ignited in the lower chamber of the machine. As the resulting energy passes through the neck and into the cone it develops into a force that becomes a shock wave. This shock wave then travels at the speed of sound through the cloud formations above, a disturbance which manufacturers claim disrupts the growth phase of hailstones.
Manufacturers claim that what would otherwise have fallen as hailstones then falls as slush or rain. It is said to be critical that the machine is running during the approach of the storm in order to affect the developing hailstones, although all manufacturers unanimously agree that the area of effect of their device is only 100 to 200 square meters directly above.
There is very little empirical evidence in favor of the effectiveness of these devices. A 2006 review by Jon Wieringa and Iwan Holleman in the journal Meteorologische Zeitschrift summarized a variety of negative and inconclusive scientific measurements, concluding that "the use of cannons or explosive rockets is waste of money and effort."