Published April 4, 2019 in the Maryville Daily Times. Read the original web version with paywall here.
It sounded like a sonic boom and felt like a train coming, Cassandra Brown said from her porch in South Maryville.
But three doors down, a neighbor reported no such disturbance.
A series of brief, sudden earthquakes were reported by several residents in the Sandy Springs neighborhood on Thursday, the latest in a mysterious spate of recent tremors that have rattled a tightly defined area— and appear to vanish at its edge.
“The one today was the biggest I’ve felt,” said Jeremy LaDuke, who described a large boom around 1:10 p.m. and then two smaller ones about an hour later. “I’ve never experienced anything like that.”
LaDuke said he and his neighbors started talking about the tremors in late July last year, after the first one hit. Over the next four or so months, he recorded six more, though he stopped keeping track after they became commonplace.
“They’ll wake us up in the middle of the night,” he said. “We got earthquake insurance a month ago because of it.”
But while the tremors — which go largely unrecorded by the U.S. Geological Survey — are well known in the neighborhood, LaDuke said he’s found few households that experience them outside a half-mile radius from Sandy Springs Park.
Every one of the six calls made to The Daily Times newsroom reporting earthquakes Thursday were from residents who lived within that radius.
Short-range earthquakes are uncommon but not unheard of, says Becky Darrell, a former geology professor at the University of Tennessee. She said she experienced Thursday’s tremor as a “big loud boom” from her home on Old Niles Ferry Road.
“They’re mild, but they scare you when you don’t know what it is,” she said.
Maryville sits almost directly on top of the Dandridge/Vonore fault line, according to a research report published in the American Geophysical Union’s 2017 publication. The report also describes the rock strata in the area as relatively brittle.
But why these acutely pronounced tremors would be felt so strongly in Sandy Springs, and little elsewhere, remains unclear.
“We’re all scratching our heads wondering what in the world is going on,” LaDuke said.
A private seismographic station in Tuckaleechee Caverns, 13 miles to the east, recorded two smaller movements and then a larger one — “a definite, 100 percent spike,” said Benjamin Vanada, the station’s operator.
“I can’t tell if it’s an earthquake or a blast,” he explained, “but it was at least local.”
One man, who lives on South Maple Street but declined to share his name, said the motion was so severe that he worried his house was coming off its foundation.
Zooming out, the sudden uptick in seismic activity over the last year described by LaDuke and others is borne out by data from the U.S. Geological Survey, which shows a dramatic increase in recent years across the broader region.
Between 2001 and 2010, there were 70 earthquakes in Blount County, the USGS’s online maps show. But from 2010 to the present, that number has more than doubled to 198— with 47 in the last year alone.
More tremors will likely come. Shortly after 5 p.m., the newspaper received three more calls describing another two tremors in quick succession.
“It happened again,” said Sam Kipton, who lives on South Magnolia Street. “It sounded like someone set off a dynamite blast a couple of blocks away.”