A coal mine bump (a bump, a mine bump, a mountain bump, or a

rock burst A rock burst is a spontaneous, violent failure of rock that can occur in high-stress mines. Although mines may experience many mining-related seismic events, only the tremors associated with damage to accessible mine workings are classified as ro ...

) is a

seismic Seismology (; from Ancient Greek σεισμός (''seismós'') meaning "earthquake" and -λογία (''-logía'') meaning "study of") is the scientific study of earthquakes and the propagation of elastic waves through the Earth or through other ...

jolt occurring within an underground mine due to the explosive collapse of one or more support pillars. In

room and pillar mining Room and pillar or pillar and stall is a variant of breast stoping. It is a mining system in which the mined material is extracted across a horizontal plane, creating horizontal arrays of rooms and pillars. To do this, "rooms" of ore are dug out ...

, tunnels are advanced in a rectangular pattern resembling city streets (tunnels), leaving behind blocks (pillars) of coal. To a miner, a partially completed tunnel resembles a room dug into the coal seam. As mining proceeds, the weight of rock overburden previously supported by coal mined from rooms is redistributed to pillars. If that weight exceeds the strength of a pillar, the pillar can fail by crushing or exploding. An explosive failure is called a “bump.”{{cite news , first=Seth , last=Bornstein, first2= Jennifer , last2=Talhelm , title=Stress Causes Killer Mine Bumps , date=2007-08-17 , publisher=Associated Press , URL =http://usatoday30.usatoday.com/news/topstories/2007-08-17-2823715890_x.htm?csp=34 , work =USA Today In the eastern United States' coalfields, bumps are more likely when the

overburden In mining, overburden (also called waste or spoil) is the material that lies above an area that lends itself to economical exploitation, such as the rock, soil, and ecosystem that lies above a coal seam or ore body. Overburden is distinct from tai ...

is at least 500 feet (150 m); where a strong, overlying

stratum In geology and related fields, a stratum ( : strata) is a layer of rock or sediment characterized by certain lithologic properties or attributes that distinguish it from adjacent layers from which it is separated by visible surfaces known as ei ...

, such as sandstone, occurs near the coalbed; and with a strong, inflexible floor. In the United States, the number of deaths from bumps had dropped off dramatically since the early 1990s, but fatalities are more common in the West where mines often run deeper. Bumps are three times more likely in room-and-pillar mines, and are even more common in mines that do

retreat mining Retreat mining is the removal of pillars in the underground mining technique known as room and pillar mining. In the first phase of room and pillar mining, tunnels are advanced into the coal or ore body in a rectangular pattern resembling city ...

, in which the pillars are removed as the miners retreat towards the mine entrance with the intent of allowing an orderly collapse of the mine.

Incidents

The

Springhill Mining Disaster Springhill mining disaster may refer to any of three deadly Canadian mining disasters that occurred in 1891, 1956, and 1958 in different mines within the Springhill coalfield, near the town of Springhill in Cumberland County, Nova Scotia. In t ...

was a bump that occurred in

Springhill, Nova Scotia Springhill is a community located in central Cumberland County, Nova Scotia, Canada. The community was founded as "Springhill Mines." Coal mining led to economic growth, with its incorporation as a town in 1889. The mines in the Springhill coal ...

Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by tot ...

on October 23, 1958. Debate over the cause of the August 6, 2007,

Crandall Canyon Mine The Crandall Canyon Mine, formerly Genwal Mine, was an underground bituminous coal mine in northwestern Emery County, Utah. The mine made headline news when six miners were trapped by a collapse in August 2007. Ten days later, three rescue worker ...

disaster, which took place 1,800 feet beneath the surface, raised public awareness about coal mine bumps. Seismologists at the University of Utah and the University of California, Berkeley concluded that an associated 3.9 magnitude temblor was likely caused not by an earthquake, but by the collapse itself."Seismologists confirm Utah mine collapse probably caused temblor", U.S. Berkeley press release, August 9, 2007, Retrieved August 17, 2007
/ref> The mine's owner, Robert E. Murray, adamantly disagreed."Owner of Utah mine is a famously combative figure
''

Boston Herald The ''Boston Herald'' is an American daily newspaper whose primary market is Boston, Massachusetts, and its surrounding area. It was founded in 1846 and is one of the oldest daily newspapers in the United States. It has been awarded eight Pulit ...

''. Retrieved on August 10, 2007.

References

External links

Coal Mine Bump Data: Five Case Studies
Coal mining Seismology