Pentremawr Colliery outburst, 1945

On 3 July 1945 an outburst of gas and some 600 tons of coal at Pentremawr Colliery, an anthracite slant mine at Pontyberem in the Gwendraeth valley, killed two miners. It was the first of the outbursts that marked the colliery's later years.

Cause

An outburst: a sudden release of methane carrying a mass of shattered coal, about 600 tons, from seams made unstable by the faulting of the western anthracite field.

What happened

Pentremawr, the Capel Ifan slants, worked the anthracite of the western coalfield, where faulting had dogged the colliery from its start and work on a fault in 1939 had led to the eight-foot Big Vein. The geology made the mine prone to sudden emissions of methane and coal. On 3 July 1945, under the manager J. Nicholas, an outburst of gas and about 600 tons of coal killed two men. Worse followed: the Big Vein threw out about 1,000 tons of coal dust in 1966 without loss of life, and in 1971 an outburst at the linked Cynheidre and Pentremawr workings killed six.

Recorded claims

Individual factual claims, each attached to the source(s) that support it below. Where sources disagree, both are kept.

• On 3 July 1945 an outburst of gas and about 600 tons of coal killed two miners at Pentremawr Colliery, Pontyberem. ^1,2
• The deaths were caused by a sudden outburst of methane with coal from the faulted anthracite seams. ^1,2
• The colliery's manager in 1945 was J. Nicholas. ²

Related terminology

Mining terms this disaster is structurally linked to, with the nature of the relationship.

• Coal (contextual relationship)
  Named 5 times in this record, first in the summary: “On 3 July 1945 an outburst of gas and some 600 tons of coal at Pentremawr Colliery, an anthracite slant mine at Pontyberem in…”
• Colliery (contextual relationship)
  Named 3 times in this record, first in the summary: “…July 1945 an outburst of gas and some 600 tons of coal at Pentremawr Colliery, an anthracite slant mine at Pontyberem in the Gwendraeth valley,…”
• Fault (contextual relationship)
  Named in this record’s narrative: “…where faulting had dogged the colliery from its start and work on a fault in 1939 had led to the eight-foot Big Vein. The geology made the…”
• Outburst (contextual relationship)
  Named 5 times in this record, first in the summary: “On 3 July 1945 an outburst of gas and some 600 tons of coal at Pentremawr Colliery, an…”
• Slant (contextual relationship)
  Named twice in this record, first in the summary: “…gas and some 600 tons of coal at Pentremawr Colliery, an anthracite slant mine at Pontyberem in the Gwendraeth valley, killed two miners. It…”

Sources

1. (secondary) Pentremawr Colliery — Wikipedia
2. (secondary) Pentremawr Colliery (NMRS South Wales collieries) — Northern Mine Research Society

Record created: 23 October 2026 · Last researched: 23 October 2026