Glen White, a science instructor at Columbia College, published a report online in September 2014 explaining the mysterious loud noises were likely coming from a U.S. Army ammunition storage depot more than 100 miles away in western Nevada.

In recent days, White's report has gained attention from regional media organizations.

Hawthorne Army Depot in Nevada says it destroys obsolete or excess munitions for the Department of Defense year-round, Monday through Friday, between the hours of 11 a.m. and 2 p.m. Methods of disposal include blowing up explosives.

"They're using explosives to destroy explosives," White said. "They want the explosion so big it actually vaporizes the metal."

White determined the depot as the probable origin of the booms after a chance meeting last August with researchers from Southern Methodist University in Texas, who installed a sensor at Columbia College as part of a larger project to monitor nuclear and conventional bomb detonations in other parts of the world.

"This was just another tool to detect nuclear and other large bombs that someone might be testing far away," he said.

White found out SMU researchers have been working with the Hawthorne base for over a decade, using explosions at the site to help calibrate their sensors, which is one of the reasons they chose Columbia College as a location.

While the team was installing the sensor last summer, White said they actually heard and felt the booms themselves.

"They said it was so loud it shook the enclosure where their instruments are kept," he said.

Mother Lode residents have long questioned the origin of the so-called "mystery booms" sometimes heard throughout the region, but one local scientist believes he may have stumbled upon the explanation.

The booms have long intrigued White, a geologist. He set up a Facebook group in 2014 called "Mother Lode Mystery Booms" where residents can share their experiences.

White said he's heard many theories about the origin of the booms, with some blaming them on seismic activity, mining operations, top-secret military aircraft testing and even aliens.

"If it's secret military testing or secret mining, they're not doing a very good job at keeping it a secret," he said. "These are awful big booms."

White also dismissed the idea of the loud noises being caused by seismic activity or movements in tectonic plates, due to the lack of a coinciding earthquake.

Many on White's Facebook page have reported hearing the noises midday during the workweek, which coincides with the Hawthorne base's ammunition disposal schedule.

White said the noises could be traveling so far because of the energy waves from the explosions bouncing off atmospheric layers. They are typically heard during the summer months when conditions are just right, he added.

"The thickness of the atmosphere, the temperature, density in the air - all of that contributes to how these energy waves bounce off the atmospheric layers," he said.

Those who live near the military installation may not even hear the explosions because of what White described as a "zone of silence."

White said that people who lived near Mount St. Helens when it erupted in 1980 reportedly couldn't hear the noises from the volcano, while others who lived farther away did.

"People tend to imagine that energy waves from an explosion would radiate out uniformly, but waves bend and refract," he said. "So people that are maybe 20 miles away from these huge explosions don't even hear it."

White wrote in his report that it "does not attempt to address the 'mystery booms' reported outside of the Mother Lode region, nor is there any attempt to explain anecdotal reports of historical booms."

He also acknowledged it doesn't explain reports from residents of booms heard during the night or on weekends, which he said would require more testing.

Still, some are skeptical that any of the noises are coming from the Hawthorne base.

"They're sure that maybe I'm part of the cover up and it's really secret military weapons or all kinds of wild things," he said. "Science is based on skepticism, it's good. But if they have an alternative hypothesis, put your data out there …It should be able to stand up to the scrutiny."

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