Task: Question Generation
Input (English): Passage: Senghenydd—Senghennydd in Welsh—is situated at the northern end of the Aber Valley, approximately four miles (6.4 km) north-west of Caerphilly and eleven miles (18 km) north-west of Cardiff. When geological surveys for coal began in 1890 it was a farming hamlet of around 100 people. Coal was found, and sinking of the first mineshaft for Universal Colliery—which was owned and developed by William Lewis—began in 1891; the first coal was extracted in 1896. The colliery's two shafts were both 1,950 feet (590 m) deep, the downcast Lancaster and the upcast York. Development of the pit coincided with the Boer War, and sectors of the underground workings were named after key places in the war, such as Pretoria, or the lifting of the sieges at Ladysmith, Mafeking and Kimberley.
South Wales miners, including those at Universal, were paid on a rate determined by the Sliding Scale Committee, which fixed wages on the price coal fetched at market. When the price of coal slumped in the late 1890s, low wages led to industrial unrest and, in 1898, a strike that the men at Universal joined at the end of April. The Monmouthshire and South Wales Coal Owners' Association refused to replace the scale, and the strike ended on 1 September with some small concessions granted by the owners. The colliery resumed production and in 1899 was producing 3,000 long tons (3,400 short tons) of coal a week.The industrial historians Helen and Baron Duckham consider Universal Colliery to have been "an unlucky mine". At approximately 5:00 am on 24 May 1901 three underground explosions occurred as the night shift was exiting the pit. Because the explosion damaged the pit winding gear, it took time to clear the debris from the pithead to allow rescuers to begin work. They descended at 11:00 am and rescued one man, an ostler, found alongside the corpse of the horse he was tending. There were no other survivors and 81 men died. Although the funerals for the victims started four days later, the rescue and recovery operations lasted for six weeks.The Mines Inspectorate began an enquiry, chaired by the mining engineer William Galloway. The report was published on 15 July. It stated that the mine was hot with high levels of coal dust present. The method used to load coal onto underground trucks created quantities of dust, which had aggravated a small explosion and created a chain reaction of related explosions throughout the workings. An inquest held in October concluded that various safety precautions had not been followed, and had the mine been sufficiently watered it would have reduced the coal dust held in the air. The colliery had further problems in October 1910 when a heavy roof fall in the Mafeking return released trapped firedamp, which caused the mine to be temporarily evacuated.
Output (English): What got trapped and caused Universal Colliery to be evacuated?