Regional Bumps: Case studies from the 1958 Bump Symposium 

J. Whyatt, National Institute for Occupational Safety and Health (NIOSH), Spokane Research 

Laboratory (SRL), Spokane, WA 

F. Varley, NIOSH, SRL, Spokane, WA 

The findings and conclusions in this report are those of the authors and do not necessarily represent the 

views of the National Institute for Occupational Safety and Health. 

I. Abstract 

 A variety of dynamic failure cases with 

regional impact were described at a bump 

symposium held in 1958. These types of events, 

while rare, are of particular interest because 

their ability to impact a large area has disaster 

potential. These cases can be grouped into two 

broad classes of events by mechanism. These 

are (1) slip along steeply dipping faults and (2) 

fracturing of strong strata above, or below, the 

coal seam. Both failure modes produce 

dynamic or “shock” loads on the perimeter 

(roof, rib, floor) of mine openings. Special 

consideration should be given to these failure 

modes in planning of deep coal mines since 

their occurrence is not within the professional 

experience of many contemporary workers, and 

their potential is not evaluated by many of the 

analysis tools commonly used to evaluate 

hazards in coal mine plans. 

II. Introduction 

Local pillar bumps and outbursts of coal are a 

concern in many coal mines, and have received 

considerable attention from industry and 

regulators. Sudden, dynamic failures with 

regional impact have been much less common. 

This is important, since the bump cases reviewed in 

this paper show that a bump with regional impact is 

not simply a large version of a local bump – it may 

well be caused by a different mechanism. 

Given the rarity of regional scale bumps, a long 

view is needed to capture case histories and 

insights into these phenomena. The historical 

literature is marked by periods of relatively intense 

interest in such events, often in response to 

particularly damaging or disastrous occurrences. 

This literature gives a variety of names to these 

events, including bounces, district bumps and 

shock bumps, that often imply a particular 

mechanism, at least with respect to a particular 

mine or district. The general term “regional scale 

bump” is used in this review to avoid implicit links 

to these mechanisms. 

A Bump Symposium held at the 1958 Annual 

Meeting of AIME marks one historical era of 

heightened interest in regional scale bumps. The 

introduction to this symposium defines the term 

“mountain bump” as the “sudden rupture of one or 

more coal pillars under excessive stress” and goes 

on to say that these “bursts occur with varying 

degrees of violence and sometimes include 

adjacent strata, especially the bottom rock.” The 
problem is characterized as “extremely 

complex” and preventative measures, to be 

successful, must be “based on a thorough study 

of conditions in the individual mine.” This 

characterization remains appropriate, although 

the discussion predates modern longwall 

mining. However, longwall mining was a topic 

of considerable discussion in 1958, primarily as 

a means to control bumps through caving. 

Thomas (1958) credits the late George S. Rice, 

former chief mining engineer of the U.S. Bureau 

of Mines, with being an early advocate for 

“open-ended” longwall mining which had been 

“most successful in combating the bump hazard 

in mining coal under deep cover, especially in 

Great Britain.” 

The Symposium Proceedings, published in two 

successive issues of Mining Engineering, are 

preceded by a summary titled “Progress in 

Control.” This title is consistent with the 

optimistic tone of many of the published papers, 

including one titled “Coal Mine Bumps Can Be 

Eliminated.” Confidence within the Bureau of 

Mines, in particular, had been sufficiently high 

that there was a ten-year pause in bump research 

dating from Rice’s retirement until 1951, when 

three bumps involving fatal injuries occurred. 

This over-confidence was further underscored 

by the 1958 Springhill bump disaster, which 

claimed 75 miners. 

The waxing and waning of interest in bumps, 

particularly regional bumps with disaster 

potential, is likely a result of their rarity. This 

rarity means that few mining professionals can 

apply personal experience to evaluation of their 

potential in practice. As such, there is a real 

danger of ignoring these types of events, 

analogous to the ever-present temptation to 

build on that 100-year flood plain. 

As in 1951, and 1958, we are reminded that 

bumps of regional scale, while uncommon, have 

not ceased. This paper looks at historical 

descriptions of bumps with regional scale, in the 

hope that by investigating dynamic failure modes 

with potential to create the next disaster, that 

disaster might be averted. Such a pursuit is central 

to the mission of the National Institute for 

Occupation Safety and Health (NIOSH) – and of 

great concern to our partners in industry, labor and 

academia. This paper presents the beginning of an 

effort to address this issue – stated as: 

“How do we evaluate and manage the disaster 

potential of various modes of regional scale 

dynamic failure in deep coal mines?” 

The 1958 Symposium papers describe a variety of 

regional scale bumps that can be sorted into two 

broad classes of events that were caused by (1) slip 

along faults in the overburden and (2) fracturing of 

strong strata above, or below, the coal seam. Both 

failure modes produce dynamic loading of mine 

opening perimeters. In the first case, dynamic 

loading is typically described as widespread 

shaking, particularly along a fault trace. In the 

second, loading is described as an impact generated 

by sudden failure of hard strata. Treatment of 

these two modes by the 1958 symposium is 

reviewed here. 

III. Fault-Slip Bump Cases 

The first set of regional bump cases were selected 

from events reported by Peperakis (1958) as related 

to the Sunnyside fault zone. Two types of bumps 

are described, localized bumps at the face that 

occurred during mining in close proximity to the 

fault, apparently as stress concentrations were 

encountered, and widespread shaking of main 

accessways by slip within the fault zone. This 

review focuses on the later. These bumps typically 

occurred a great distance from active pillar 

workings and were associated with faulted 

structures. 

Peperakis describes terrain above the Sunnyside 

Mine as “exceedingly rough.” Overburden depth 
increases quickly, reaching 2000 ft of 

overburden within 2700 ft of the outcrop. Much 

of the overburden consists of massive sandstone 

but the immediate roof is described as 

“generally very poor.” Seismic shaking of the 

immediate roof and ribs by large fault slip 

events accounts for a large portion of the 

damage. The floor is a strong massive 

sandstone bed 20 to 50 ft thick. Faulting is 

described as “very extensive” with maximum 

displacements of 33 to 90 ft. 

The Sunnyside fault lies along a roughly 3.5 

mile southeast trend, subparallel to the strike of 

bedding with displacement reported to be 30 ft 

(Clark, 1928). Osterwald et al (1993) report on 

more recent mapping of the northwest-trending 

Sunnyside fault zone (figure 1). They describe 

the fault zone as follows: 

“... a belt of fractures about 1930 m (1.2 miles) 

wide in the southern part of the [Sunnyside] 

district, but it narrows to a single break in the 

northern part of the district. It dips almost 

vertically, and the stratigraphic separation 

across the zone is commonly about 9 m (30 ft). 

The southwest side is downthrown.” 

Peperakis (1958) reported the occurrence of 

“extremely violent bumps near the intersection 

of the main slopes of No. 1 mine with the main 

Sunnyside fault” and concluded that “most of 

the really severe bumps that have struck the 

workings in recent years have taken place close 

to the main Sunnyside fault.” Many of these 

bumps produced widespread shaking of the 

mine (and surface, in many cases), suggestive of 

fault slip movement. Recurring damage to 

slopes (main accessways) well outby the mining 

front was an added source of concern. Many of 

these bumps were described in detail at the 

symposium. A selection are summarized here. 

The first occurred in December of 1944 with the 

mine almost entirely on development (i.e. little 

or no pillar mining). A major seismic event 

“initiated working of a 350-ft section of roof that 

caved over the ensuing 45 minutes.” Other slopes 

were described as “badly shaken” but did not cave. 

A similar event eight years later, in November of 

1952, was felt through most of the mine and on the 

surface, causing extensive rib sloughage in the 

slopes, in some cases extending to the portal. 

Figure 1 The main Sunnyside fault zone in the Sunnyside 

1,2 and 3 Mines (after Osterwald, 1993). Inset is a map of 

mining to 1958. Shaded area is 4 sq. miles of worked out 

or first mined coal seam (after Peperakis, 1958). 

The 1944 and 1952 bumps were followed by a 

succession of four similar major events in 1957. 

The first two, on January 24th and 27th, caused 

considerable damage to the main slopes, including 

heaving of 1300 ft of track entry, caving of roof 

along 550 ft of main slope entries and an additional 

500 ft of main slope where heavily bolted roof 

“settled on the bolts.” In addition, top coal was 

shattered along 2000 linear feet of entries and 

widespread entry roof “breakage” was reported. 
Figure 2 Sketches by Holland (1958) illustrating two variations of his proposed bump mechanism (not to scale). Top, 

failure of a pillar remnant suddenly transmits stress to the mining front. Bottom, failure of a strata lever that has 

reduced stress on the coal seam at B fails, suddenly increasing stress at B while reducing stress on coal at the mining 

front. 

A similar pair of events occurred in December 

of 1957. The first induced bursting of 220 feet 

of “main slope pillar,” filling the manway with 

rock and badly shaking the main slope. Heavy 

support, including roof bolts, 12x12 inch 

crossbars and cribs, was credited with 

preventing damage. The second was a violent 

bump that was recorded by men “working at 

four points along three different fault planes” 

with a lateral extent of 7000 ft. 

Peperakis identified strong or well-reinforced 

roof as the key to prevention of damage and 

accidents in “all areas subject to bumps” at the 

Sunnyside Mine. Support suggestions included 

roof bolts in combination with cribs, crossbars 

on cribs, and 16-in diameter props, augmented 

by the “steel yieldable arch type of support” in 

slope areas and haulageways. This emphasis on 

roof support is a particular, local conclusion 

aimed at preventing damage from seismic 

shaking of the “generally very poor” roof rock 

at the mine. 

IV. Strata-Failure Bump Cases 

The second set of regional bump cases was 

selected from events reported by Holland (1958) 

and Campbell (1958) as related to failure of strong 

strata above and/or below the coal seam. This 

group of regional scale dynamic failures is 

characterized by widespread damage outby the 

retreat line – with or without damage on the line. 

The location of damage behind the mining front 

while, in some cases, the mining front remains 

unaffected, has been attributed to strong strata 

acting as a lever sitting on a fulcrum which is the 

mining front. Failure of the lever then causes 

impact loading of the coal seam behind the mining 

front. 

Herd (1930) provides an early version of this 

explanation in the context of the Springhill Mine as 

follows (pp. 178-179): 

“This sandstone, being very strong and compact, 

has not the ability to fall or shear until a very 

considerable area has been excavated, during 
which time it is hanging back in the waste 

supported on a fulcrum at the coal face, 

resulting in an upward stress in this band and 

those above, reaching far over the solid coal. 

When this band finally breaks somewhere back 

in the waste, or possibly only slips very slightly 

on a fracture, the cantilever effect ceases, the 

rocks in upward strain over the coal are subject 

to a sudden reversal of stress and the coal ahead 

of the face is struck a sudden and hammerlike 

blow... This may explain damage up to 1350 ft. 

ahead of the wall faces...” 

Holland (1958) also described (and illustrated, 

in figure 2) how failure of hard strata might 

cause impact loading of large areas behind the 

pillar line (or working face in a longwall 

method). He describes impact loading as 

follows: 

“... impact loading, which comes about because 

stratified mine roof spans an opening by acting 

as a series of beam or plates. Such structures 

impose high stress in support areas and perhaps 

relieve stress in areas behind the support. Then, 

as illustrated in figure 2, the failure of such a 

beam or plate or a failure of its support (such as 

a pillar or pillar remnant) can cause a high 

impact load on the pillar adjacent to the failed 

support, or, if the roof beam actually fails, on an 

area behind the pillar. Action such as this may 

cause a rock burst at the pillar line or at a place 

considerably removed from a pillar line.” 

Holland also cautions that “this mechanism has 

not been comprehensively analyzed” – a caveat 

that still applies. Indeed, no convincing analysis 

of this mechanism is known to the authors, 

despite the availability of sophisticated 

numerical modeling tools. Nonetheless, this 

concept continues to be the “state-of-the-art” 

description of this type of bump in 

contemporary works (e.g. Peng, 2008). 

Holland presents a number of bump cases from 

which he deduced this mechanism, including a 

large event that caused extensive damage behind 

the pillar line while leaving the pillar line 

undamaged (figure 3). 

Campbell (1958) provides a number of similar 

bump cases from the Springhill Mine. The first of 

these occurred Dec. 6, 1924 (figure 4). Damage, 

marked by crosshatched zones and letters, occurred 

primarily in levels developed on strike, and was 

described as “rails were thrown up against the roof 

by the eject coal and pavement [floor] strata.” This 

case differs a bit from Holland’s example in that 

that pillars were not fully developed before retreat. 

Also, the damage is reported as originating from 

failure in the floor, rather than the roof. 

Figure 3 A very large district bump described by 

Holland (1958) spared the pillar line but produced several 

thousand tons of debris in areas behind in this un-named 

mine. Shading on pillars adjacent to the gob in this 

drawing show active mining. Orientation was not given. 
Holland began with the assumption that the 

strong, brittle stratum that drives failure forms 

the immediate roof. However, the proposed 

mechanism is equally plausible for a key 

bridging stratum located in the floor, at least 

until the gob develops sufficiently to confine the 

floor. 

Longwall mining was introduced at Springhill in 

August of 1926 with starting of the 220 ft wide 

5700 and 5900 East longwalls (Herd 1930), in 

an attempt to control bump hazards. Longwalls 

were developed on dip with levels (gateroads) 

developed on strike for access to the wall. On Oct. 

12, 1928, an event damaged a level for a length of 

1350 ft, starting a little more than 150 ft from the 

wall, which was not affected. As was the case in 

1924, damage was characterized by “ejected coal 

and pavement [floor],” suggesting the basic 

district-bump mechanism had not changed with the 

change in mining method. In general, Campbell 

(1958) found that “the most dangerous zone was on 

the levels for a distance of several hundred feet 

from the face.” 

Figure 4 Location of damage from a large bump at Springhill Mine, Dec. 6, 1924. Damage to levels is marked by 

crosshatched zones and letters. After Campbell (1958). 

V. Discussion and Conclusions 

This paper presents historical cases of large 

bumps with regional impacts on coal mines that 

fall into two classes by mechanism. These are 

(1) slip along faults in the overburden and (2) 

fracturing of strong strata above, or below, the 

coal seam. While these general mechanisms 

have been identified, detailed understanding is 

lacking. Both failure modes produce dynamic 

loading of mine opening perimeters (roof, rib, 

floor) and both impact areas outby the retreat 

line. The character of dynamic loading, 

however, differs significantly. 
 In the first case, the low frequency seismic 

shaking over large areas is typical of mining 

induced seismic slip of a pre-existing fault. 

Peak particle velocities in such cases are 

relatively low and can be handled by many 

support systems, even those dating from 1958, 

as is evident in recommendations put forward 

by Peperakis. 

In the second case, the relatively severe but 

more focused impact loading is typical of 

seismic rupture of hard, brittle rock. The high 

frequency component of dynamic loading 

creates high peak particle velocities that 

challenge support not specifically designed for 

such loading. Even the best support is often 

reduced to controlling rather than preventing 

damage. Application of the recommendations 

put forward by Peperakis in this case would be 

relatively futile. 

Other regional scale failures have been 

addressed by companion papers, including a 

review of sudden floor heave events in deep 

western coal mines (Maleki et al, 2009), and a 

review of large scale collapse of overburden 

over evaporite mines, many of which involve 

overburden remarkably similar to that over 

some deep coal mines (Whyatt and Varley, 

2008). The possibility of other mechanisms is 

being investigated. 

All of these mechanisms need to be considered 

when examining potential bump hazards in deep 

coal mines, particularly those mining within 

hard strata. While uncommon, these 

mechanisms are well represented in the 

historical record. The next step is to apply 

modern geomechanics tools, particularly 

numerical methods, to gain a better 

understanding of these mechanisms, factors that 

influence the likelihood of occurrence, and their 

control. This step is being undertaken by an 

ongoing NIOSH research project with the 

assistance of collaborators in industry and 

academia. 

While more needs to be done to fully understand 

these mechanisms and incorporate this 

understanding into the design of mines, it is 

clear that the more we can understand the causes 

and effects of these mechanisms, the better we 

can anticipate, provide protection from, and 

reduce the chances of, their occurrence. 

The focus on mechanism is a characteristic of 

modern rock mechanics. In part, this is a 

reflection of advances in our ability to compute, 

but it is also a realization that all rational ground 

support criteria depend on failure mechanism. 

This applies to empirical as well as analytic 

methods. 

The empirical approach is well-tested and 

useful. It is not, however, independent of 

mechanism. Rather, it collects successes and 

failures for common conditions with the implicit 

assumption that the failure mechanism (or 

mechanisms) is consistent. Any departure from 

common conditions and failure mechanism(s) 

may invalidate the empirical rule. 

Bieniawski (1989, p. 66) addresses this issue by 

describing the data base underlying empirical 

rock mass classification systems he reviews and 

states “The data base used for the development 

of a rock mass classification system may 

indicate the range of its applicability.” Peng 

(2008, p. 249), in discussing empirical pillar 

design formulas: “the reliability and 

applicability of the formula selected depends on 

the quality of, and range of mining and 

geological conditions covered by, case histories 

used in the calibration.” 

Control mechanisms are, necessarily, also 

closely linked to failure mechanism. This link 

may be implicit if the control mechanism has 

been developed by trial and error, or if it is 
specified by an empirical criteria, but the danger 

of extrapolation holds nonetheless. Put plainly, 

application of the wrong control mechanism to a 

given failure mechanism may increase, rather 

than decrease, the hazard to miners. 

These cases show that rare but potentially 

disastrous bumps are caused by mechanisms 

different from local pillar bumps and outbursts, 

and can originate outside the coal seam. In 

other words, regional scale bumps are not 

simply large versions of local pillar bumps and 

outbursts. Protecting against these regional 

scale events, then, requires explicit 

consideration of other mechanisms. Thus, at the 

fiftieth anniversary of the 1958 Bump 

Symposium, it is appropriate to review these 

rare but potentially disastrous types of bumps. 

VI. Postscript 

The threat posed by regional scale bumps was, 

sadly, underscored shortly after the 1958 

symposium by a truly catastrophic bump in 

October of that year at the Springhill Mine. 

Campbell (1958) set the stage for this event in 

the conclusion to his paper as follows: 

“To date some 500 bumps have been recorded 

in No. 2 mine. Many miners have been injured, 

and too often lives have been lost. It has been 

fortunate that in most cases bumps have 

occurred when men were absent from the 

affected areas.” 

He also notes “three retreating longwalls – the 

13,000, 13,400 and 13,800 walls – are in 

operation today.” These walls were operating in 

hard strata under up to 4,350 ft of overburden. 

Fortune ran out for the No. 2 mine on October 

23rd of 1958, when a disastrous bump hit levels 

accessing all three walls, and portions of the 

faces, killing 75 miners. Notley (1984) 

described the damage as follows: 

“The final bump occurred at 8:06 p.m. and 

affected all three longwall faces. The pavement 

of the four levels leading to the faces was 

heaved for up to 400 feet from the face and coal 

bursting from the ribs completely filled the level 

for distances ranging from 90 feet on the 13,400 

level to 434 feet on the 12,600 level. On the 

longwall faces the floor had heaved, smashing 

many of the timber packs, and in some places 

raising the conveyor pans to the roof. Coal 

burst from the face completely filled most of the 

face area.” 

Survivors were rescued from pockets along the 

face at the levels, after arduous excavation of 

heavily damaged levels (figure 5). This bump 

was later examined in a Ph.D. thesis 

summarized by Notley (1984), but the 

mechanism, including any similarity to those 

proposed for earlier events by Herd (1930) and 

Holland (1958) was not explored. 

Figure 5 Plan view of damage (shaded regions) 

caused by the 1958 Springhill bump which claimed 75 

lives. Survivors were rescued from relatively 

undamaged pockets at intersections between the 

longwall and the upper two levels. Gob was located 

above and to the left of the walls shown. The sketch 

was made by Dr. Arnold Burden (2008), a Physician 

assisting in the rescue, is not to scale. North is to the 

left in this sketch. 
VII. References 

Bieniawski, Z.T. (1989) Engineering Rock 

Mass Classification: A Complete Manual for 

Engineers and Geologists in Mining, Civil, and 

Petroleum Engineering. John Wiley & Sons, 

251 pp. 

Burden, Arnold (2008) Eyewitness account of 

Springhill rescue, accessed November, 2008 at: 

http://web.archive.org/web/20041013211103/htt

p://town.springhill.ns.ca/1958_bump.htm). 

 Campbell, W.F. (1958). Deep coal mining in 

Springhill No. 2 Mine. Mining Engineering, 

Sept. 1958, pp 987-992. 

Clark, F. R., (1928). Castlegate, Wellington, 

and Sunnyside Quadrangles, Carbon County, 

Utah. US Geol. Survey Bull. 793 . 

Herd, W. (1930) Bumps in No. 2 Mine, 

Springhill, Nova Scotia. AIME Trans., 88, 151-

191. 

Holland, C. T. (1958) Cause and occurrence of 

coal mine bumps. Mining Engineering, Sept. 

1958, pp 994-1004B. 

Maleki, H, C. Stewart, R. Stone, J. Abshire and 

J. Whyatt (2009). Analysis of sudden floor 

heave in deep western U.S.mines. Paper 

prepared for presention at the 2009 annual 

meeting of the Society of Mining Engineers.. 

Notley, K.R. (1984). Rock mechanics analysis 

of the Springhill Mine disaster (October 23, 

1958). Mining Science and Technology, 1984, 

1, 149-163. 

Osterwald, F.W., C.R. Dunrud and D.S. Collins 

(1993). Coal mine bumps related to geologic 

features in the northern part of the Sunnyside 

District, Carbon County, Utah. USGS Prof. 

Paper 1514, 1993, 76 pp. 

Peng, S.S. (2008) Coal mine ground control. 

3rd Edition. Pub by Dept of Mining 

Engineering, West Virginia University, 

Morgantown, West Virginia, 750 pp. 

Peperakis, J., (1958). Mountain bumps at the 

Sunnyside mines. Mining Engineering, Sept. 

1958, pp 982-986. 

Thomas, E. (1958). U.S. Bureau of Mines 

Investigations and Research on Bumps. Mining 

Engineering, August. 1958, pp 878-879. 

Whyatt, J K and F D Varley (2008) Catastrophic 

Failures of Underground Evaporite Mines. 

Proceedings of the 27th International 

Conference on Ground Control in Mining, July 

29 - July 31, 2008, Morgantown, West Virginia. 

Peng SS, Mark C, Finfinger GL, Tadolini SC, 

Khair AW, Heasley KA, Luo-Y, eds., 

Morgantown, WV: West Virginia University, 

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