This year's unseasonably warm winter weather mixed with waves of bitterly cold air has brought a rare and often frightening natural phenomenon back to Vermont—Cryoseisms. A cryoseism, or frost quake, occurs after a sudden deep freezing of the ground, when the pressure created from water expanding into ice abruptly causes stress fractures in underground soil and rocks. The result of these fractures can produce localized ground shaking and noises similar to an earthquake. While usually alarming, frost quakes typically pose little physical harm beyond occasionally causing a small crack in the ground where the frost quake occurred.
On the night of January 8, 2016 and morning of January 12, 2016,
several Shelburne residents in the vicinity of the La Platte River near Falls Road reported hearing mysterious sounds that many equated to an earthquake. One resident, despite not living near a highway, described the event as similar to the rumblings caused by a large semi-truck driving nearby, while another on Front Porch Forum likened her experience to a large boulder rolling towards her house.
In each case, the startled residents described the sound as very loud and different from thunder, but no one at the time could explain exactly what caused the earthquake-like tremors.
After speaking with state geologist, Marjorie Gale, and confirming that there was
no seismic activity on either of those days, she explained that in 1955, geologists mistakenly reported frost quakes in Burlington as minor earthquakes in the state's earthquake catalog, and that
local frost quakes could have caused the mysterious rumblings in Shelburne. However, given their relative infrequency and generally minor effects, the Vermont Geological Survey does not track frost quakes. As a result, there is little historical scientific data regarding the geographic locations, cause, or frequency of frost quakes in the state.
Comment: Zhupanovsky volcano in Russia's Kamchatka Peninsula, also part of the Pacific Ring of Fire, spewed ash 8 km high yesterday.